4:;

    
 

  

1'anvwm
1

11“ ‘
1 19111., 1‘11“ 1} s1 '11 111,1 I111; .‘
1111.13] I , Iu'11‘1‘1- (vhli'I ’

wfigMM
‘11‘1""1“ ”11‘ 1‘11“.

    
  

  
   
 
  

III1I1IIII51I III
1III ;,
.1 :mg
111%1 .I 311,1 .14 1 1L
'1}. .012: {.1

  
 
 
  
   
    
  
  
   

Ado!-
“‘_'.rI

 
  
  
 

  

          
 

 

<—.‘P."

-.:

 
  
 

 
 
   
  
    
    
  
   
       

   

.‘?_-.,;;__"~.—1 -:-':.
" ' 322‘:

   
   
     
      
         

  
   

           
 

   
  

   

 
 
  
   
 
  
 
   
   

 

    
 
 
 
   
   
 
 
 

    
   
    
   
   
    
     
 
   
 
    

 

    
   
 
  
 
 
 

     
 
   

     

 
   
  

  

:1

   

~ 1
. 1 1% 1L\ 1 IE":
1| 1 , 1111111113.; .1111 1. 1 11
1 "31.1-1"1‘1‘1'1‘31‘13‘ :1. 1.11 1‘
. . '111X ‘ 511- 113.171 119';
1' ' .1 ' .1 11.111 1511-? 1 113113113111 :1 1.1 .171. .1 1-1-5 .
.. £111 '11 v 1- ' "1 '1' . 1 L 13’ 5113;? '. '31 151 . ~1 ; I: ! I 'I . .
H ”“1111 .15&1*- 1&11111 ~1M1wm1111 ‘ 1%:
“ 1,111'11111IIJUQ§ 12‘3111111‘2I‘9I 1'15"“ I 'I LEE, 1.11111‘flp1'i'1' I. L,.I§1y' 7 I r) ‘ 31.39;! '-,
11...“ww11m '1Mm ' vwfi1' mm =
- .: 1,:143. : a” 1mth. .wgyyfl . 1 ”th
1 . - ‘II 1.1 '. 41:41“ I-s . ~ 133.13 1:1 . .1 II .M -. iv,
11 1g 1%w11 .Efifiy- vsgfl fibqu¢qfi . ,Hfii
'I: I IIf‘11.1,{,I1I?- . 31,12“ch 1 ”1.1:. tuifi’uha EW' (if: III III ‘ 13.1%}
1‘ 1W1 11% Ww1“%w~%% 7%.
" 1 ’ - "£12, 3111,33" 1" 31,76. w=‘:r:’i’13
“1.,1 _M 351.; ‘ , ‘ifl ii’éSrV-é
.11! 1I .1111 : l-w‘, ,
‘ 1

1
‘I .q...
.. ;

1-. W
42-1?“ .1111}: 5'11"" . Want
111,111.13
_ ’4

   

   

      
    
 
 

     

11 H

II: A”! 55; fi‘t
,» .2. 1 " .2. 1'3" 1.1-.“ 3111,: '- , 3.11.:-
.-'1é": - 1 111I'.III 5.; fig fifth-'51- “16$ ""“fifié-I ' 13%;?
-‘ .11? ' mg; 31 ' ' "5" -..- III-fl?” 't; 31“.“
111,11: I. ‘1 . ‘; V
21' -' 3-

 
 

v...—

vxz': '

o...

   

   

     

     

-
'a or
II. -

'2". «Q—

' qum. '
..-.. ..-
. . . . .‘
I. .'
,-

 
  
  
    

  
     
  
  
    

It. at. '
.11

’- 101;!;:‘
J
. .’” ,1

      
   

 
 
 

:. .5. .'.,.I--
,0 ‘I‘ .m .
i“...

. r- 0-0.“ .

   

.l

   
 
   

 
    
  
 
 
 

p.-.

   
 
  

39—3.-.
.¢ - ' ‘
:12- ‘ "

1~ .-

"".
nu...

   
 

-. . ..1 -
Y .-~’1~

‘-

  
  

 

 
  
    
 

f‘KfiI;

1I1I1 11.1‘, r}
”V

Irr’t‘u'

   

   

  
 
   

  
    

       

  
 
   
   
   

    

    
    

     
 

   
   
  
  

 

   
  
   
 

 

    
   

. ‘. “L151III111111111. I
‘I I ‘1 II. IIIrij1‘
1 11:11I 41111: III“ 1‘11111
1 ‘ - 19' ‘1‘1 i1 '
~ . 1.1.:-1:5:~11,.. . 1.. 1. .1.
' :- .11 .1111;1.111121111- ' . g .,

. 11.1.IvII11II.:1III..I.I11IIII1-: .I .I I II

w113pnmm1fl ,V" 3 .

':I1'1I1 "11111-11 .11; 1 _ I, .; 1 II
:11.111111.1;.1I.,I1,1.III'IIII‘ ~ I 2 'III II
II 11,111II11 [14121111111111 11‘1“; ‘ 1I . .‘I‘I‘ . -III I. II '. III.
:1 I. I I,QII1'\ V 1“ ,113I;"', .7 1 If: .I-IIIII I . I IIII
1" *1111‘1‘1‘13-“fl '1 111111311111- 11 11‘1.13=1'1’v1.1.1‘ 112‘; 1111-1111.? .11- .. :. “1513'- 1-1; 1111.13
‘I‘ I: II 1 1.1 1'itktlhuhqu1:..1‘II IIIX'I‘IZ ”’1‘41: , £1 11111., ‘1." I . 1]“ ‘. . 1. I ‘gl '1': EI1I 'II, III'II II I
1" .~ 11'- 1-1‘11‘11="1‘.'-' .1 11111-11 1-11.11.11111121111111 . 11-1 .. 1, 11.1111 . . 1. “1111.1 , .11.;
'i‘ 1‘ 1d1111151111,.11‘131.11111111'1 11111111‘111111111‘1‘ 111 ‘~ '1'" 111111,:i 'l'n‘ "' $11, Ii!- 11. 113:! -a1'1- I, 11
1 '; .1 11115117111 1112111: ,Iu111I11vII I. 111.151-12113313‘1 1. 1- 1‘1 9}. IIIII I , II .
.1 .11 .111111 11:; 1511111111111 .1111! 111.1 1111111 111 ; .1 ,:- 11.- ;I .,I
' “ ‘11 11'11111‘11'1‘: 11‘ ‘1“;"211I '-1~I.l1’1 .111.:£_1.1.r11.1'.;11~ 11 ‘41 11 1_ 11-11:.

1 111 1‘17 1111111111 11.111 I1I1 II11;:1II11!1.1I1!111;,11 1I1III1:.1111 : ‘. 11“ 1,

.1wwwwmmwfimmwm..11

11WWWWMMMWNWMW‘1WY

1 111111111111.1. 11 1.1111111-1111111- 1.. ‘

”111.. 111 11,146,1II1Q11I12II'II1 1
1. 11h111na11111 11-11111111.

SITY LIBRARIE

U | lllll

 

 

 

 

 

 

 

 

 

 

 

 

Zs lllllllllllllllllllllllllIllll

, 3 1293 01563
. it.’ 34 I)

This is to certify that the

dissertation entitled

Root-Zone pH, Calcium, and Magnesium Management
in Peat-Based Container Media

presented by

William R. Argo

has been accepted towards fulfillment
of the requirements for

Ph.D. . Horticulture
degree In

 

 

 

Major professor

Date lag/519$

MS U i: an Affirmative Action/Equal Opportunity Institution 0- 12771

 

 

 

 

LIBRARY

Michigan State
University

 

 

 

PLACE N RETURN BOX to remove this checked from your record.
TO AVOID FINES roturn on or bdoro dd. duo.

DATE DUE DATE DUE DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MSU Is An Minn-two ActiorVEqull Opportunity Intuition
mm:

ROOT-ZONE pH, CALCIUM, AND MAGNESIUM MANAGEMENT
IN FEAT-BASED CONTAINER MEDIA

By

William R. Argo

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Horticulture

1996

ABSTRACT

Root-Zone pH, Calcium, and Magnesium Management
in Peat-Based Container Media

By

William R. Argo

Optimizing the pH, Ca, and Mg management of low- and nonleaching irrigation
systems requires an understanding of how a number of sources including lime, preplant
nutrient charge (PNC) fertilizers, irrigation-water sources (IWS), water-soluble fertilizers
(WSF), root media, and plant species interact during the production of a crop to affect
pH, Ca, and Mg management initially and over time. Preplant nutrient charge fertilizers
and root media were found to have minimal effect on long-term pH, Ca, and Mg
management. By itself, the type of dolomitic liming material, it’s particle size and
incorporation rate affected the initial pH and final stable pH of an unplanted root
medium, but had minimal effect on root-medium Ca and Mg concentrations. With one
type of dolomitic carbonate lime (CaCO3 and MgCO3), a large amount of unreacted or
residual material remained once the equilibrium pH of the medium was reached. The
residual lime affected long-term pH, Ca, and Mg buffering capacity in media given
nutrient solutions (NS) containing high NH4-N, and low Ca and Mg, but not in media
given NS containing low NH4-N, and high Ca and Mg compared to the same medium
containing a dolomitic hydrated lime (Ca(OH)2 and Mg(OH)2) with minimal residual
material. In addition, the alkalinity concentration in the IWS and the NH4 : NO3 ratio in

the WSF interacted to affect the overall type of reaction (either acidic or basic) produced

by the NS in the root medium. A linear relationship was found between the concentration
of Ca and Mg in the NS and shoot-tissue Ca and Mg suggesting that other ions contained
in the NS (N H,, K, 80,) did not interfere with uptake. Instead, the primary factor
affecting uptake of Ca and Mg was their concentration in the NS, as affected by the IWS
and WSF. Differences in root medium pH and Ca and Mg uptake by nine plant species

was also studied.

Copyright by
William Robert Argo
1996

Dedication

I would like to dedicate this to my wife, Kathy. Thank you for all the love and support.

Acknowledgments

I would like to thank my advisor, John Biernbaum, for giving me the chance to go to
graduate school and for his and advise in all my projects. Thanks also goes to the other
members of my committee, Drs. Royal Hiens, Robert Schutzki, Boyd Ellis, and Darryl
Warncke. I also would like to thank my friends and colleagues Paul Fisher, Jim Faust,

Tom and Cara Wallace, Cathy Witman, and Mark Yelanich for their support.

Finally, I would like to acknowledge all the undergraduate students that worked for me
through the years. I started to list all the people, but quickly realized that I have forgotten
some of their names. For that I am truly sorry, because without their support and

dedication, a large part of my research would not have been done.

vi

Guidance Committee:

The paper format was adopted for this dissertation in accordance with departmental and
university regulations. As of October 31, 1996, Paper 1 (Geographical characterization of
greenhouse irrigation water) has been accepted for publication in HortTechnology. Paper
2 (Availability and persistence of macronutrients from lime and preplant nutrient charge
fertilizers in peat-based root media) was submitted and published in the Journal of the
American Society for Horticultural Science [121(3):453-460]. Paper 3 (The effect of
lime, irrigation-water source, and water-soluble fertilizer on root-zone pH, electrical
conductivity, and macronutrient management) was submitted and published in the Journal
of the American Society for Horticultural Science [121(3):442-452]. Paper 4 (The effect
of container root media on root-zone pH, calcium, and magnesium management with
impatiens) has been accepted for publication in the Journal of the American Society for
Horticultural Science. Paper 5 (The effect of bedding plant species on pH, electrical
conductivity, and macronutrient management) is to submitted for HortScience.

vii

Flowers have spoken to me more than I can tell in written words. They are the
hieroglyphics of angels, loved by all people for the beauty of the character, though few
can decipher even fragments of their meaning.

Lydia M. Child

viii

TABLE OF CONTENTS

Page
List of Tables .................................................................................................................. xi
List of Figures ................................................................................................................. xv
INTRODUCTION .......................................................................................................... 1
SECTION I. Geographical characterization of greenhouse irrigation water .................. 3
Abstract ........................................................................................................................ 4
Materials and Methods ................................................................................................. 6
Results and Discussion ................................................................................................. 7
Literature Cited ............................................................................................................ 12

SECTION II. Availability and persistence of macronutrients from lime and preplant

nutrient charge fertilizers in peat-based root media ................................. 18

Abstract ........................................................................................................................ 19

Materials and Methods ................................................................................................. 22

Results and Discussion ................................................................................................ 26

Literature Cited ............................................................................................................ 33
SECTION III. The effect of lime, irrigation-water source, and water-soluble
fertilizer on root—zone pH, EC, and macronutrient management of

container root media with impatiens ................................................... 45

Abstract ........................................................................................................................ 46

Materials and Methods ................................................................................................. 49

Results and Discussion ................................................................................................ 55

Literature Cited ............................................................................................................ 66

SECTION IV. The effect of root media on root-zone pH, calcium, and magnesium

management in containers with impatiens .......................................... 81
Abstract ........................................................................................................................ 82
Materials and Methods ................................................................................................. 86
Results and Discussion ................................................................................................ 91
Literature Cited ............................................................................................................. 101

ix

SECTION VII. The effect of bedding plant species on root-zone pH, calcium, and

magnesium management in containers ................................................ 114

Abstract ........................................................................................................................ 115
Materials and Methods ................................................................................................. 117
Results and Discussion ................................................................................................ 119
Literature Cited ............................................................................................................ 122
SUMMARY ..................................................................................................................... 129

APPENDIX A. Geographical characterization of greenhouse irrigation water
from the ten leading states in floriculture production ........................ 133

APPENDIX B. Nutrient composition of commercially available blended water-
soluble fertilizers used in the greenhouse industry .............................. 144

LIST OF TABLES

Table

1.

SECTION I

Suggested minimum (Min) and maximum (Max) acceptable pH, electrical
conductivity (EC), alkalinity, nutrient concentration and sodium adsorption ratio
(SAR) for irrigation water used for greenhouse plant production. Units of
measure are EC, dS-m"; alkalinity, mg CaCO3/L; Ca, Mg, SO4-S, Na, C1, B, and

F, mg-L". ..................................................................................................................

Geographical characterization of the average and median pH, electrical
conductivity (EC) alkalinity, water-soluble nutrient concentrations, Ca : Mg
ratio, and sodium adsorption ratio (SAR) measured in greenhouse irrigation
water from the United States and Canada. Water Ca : Mg ratio was calculated
using the concentrations of those nutrients in mg~L'l and SAR was calculated
from Eq. [1] using nutrient concentrations in meq-L". The number of samples
in which SO4-S was measured is less than the total sample number because only

two laboratories did SO4-S analysis .........................................................................

SECTION 11

Recommended preplant nutrient charge fertilizers and rates. The nutrient

content of the individual fertilizer salts was estimated from Hawkes et a1. (1985)

Materials used to produce blended preplant nutrient charge (PNC) fertilizers and
estimation of the amount of each macronutrient supplied by the different PNC

fertilizer based on the recommended incorporation rate. .........................................

Summary of analysis of variance by sampling date of the effect of lime grind
and incorporation rate on the log(observed + 1) transformed pH, Ca, and Mg

concentration. ...........................................................................................................

Expt. 2. Summary of analysis of variance by sampling date of the effect of an
evaporation barrier on the top layer and root zone log(observed + 1) transformed

electrical conductivity (EC) and macronutrient concentration. ...............................

xi

Page

13

14

36

...37

...38

...38

SECTION III

. Cumulative water, Ca2+, Mgzi, and 804-8 applied with the various irrigation-
water source (IWS) and water-soluble fertilizer (WSF) treatments after 17
weeks. The initial nutrient content of the root medium was not included in the
values reported below but was 0.7 g Ca2+, 0.3 g Mg“, and 0.1 g SO,-S per pot
with the hydrated lime treatments and 1.5 g Ca2+, 0.8 g Mg”, and 0.1 g SO4-S
per pot with the carbonate lime treatment. Data are the mean of six pots.
Statistical analysis indicates a three-way interaction with > 0.01 significance for
all four variables measured. . ...................................................................................... 70

. Degrees of freedom ((11), F-values (A), levels of significance (B), and mean
square from error a and b (MSE a or b) from the analysis of variance for the
log(observed + 1) transformed root-medium pH, electrical conductivity (EC),
PO4-P, Ca”, Mg”, and 804-8 concentrations at 1, 4, 8, 12, and 17 weeks afier
planting. ...................................................................................................................... 71

. Parameters of nonlinear regression analysis from fitting Eqs. [1], [2], and [3] to
percent P in tissue, based on root-medium pH at 8, 12, and 17 weeks after
planting. I and S are the intercept and slope for Eqs. [2] and [3], respectively.
The number of observations per sampling data was 48 at week four and 96
thereafter. Data from the lime treatments were used in the same analysis and are
presented in Fig. 3. The analysis of the week four data was not included
because of nonsignificance. ....................................................................................... 73

. Parameters of linear regression analysis for tissue Ca, based on the applied
concentration of Ca2+ in the nutrient solution. The number of observations per
lime treatment was 24 at week four and 48 thereafter. Data are presented in Fig.
4. ............................................................................................................................... 73

. Parameters of linear regression analysis for tissue Mg, based on the applied
concentration of Mg” in the nutrient solution. The number of observations per
lime treatment was 48 at week four and 96 thereafter. Data are presented in Fig.
5. ............................................................................................................................... 74

. Parameters of nonlinear regression analysis from fitting Eqs. [1], [2], and [3] to
percent S in tissue, based on the concentration of 804-8 in the nutrient solution
at 4, 8, 12, and 17 weeks after planting. The number of observations per
sampling data was 48 at week four and 96 thereafter. Data from the lime
treatments were used in the same analysis and are presented in Fig. 6. .................... 74

xii

SECTION IV

. Average air space (AS), water space at container capacity (CC) in a 9-cm-tall
pot, bulk density (BD), and cation exchange capacity (CEC) of six root media
composed of 70% (by volume) of the material listed below with 30% perlite.
Reported values are the mean of five samples. ........................................................... 105

. Cumulative water, Ca2+, and Mg2+ applied to plants grown in various media and
nutrient solution (NS) treatments after 17 weeks. The initial nutrient content of
the root medium was included in the values reported below. Data are the mean
of three pots from each treatment. .............................................................................. 105

. Degrees of freedom (dt), F-values (A), levels of significance (B), and mean
square error (MSE) from the analysis of variance for the log(observed + 1)
transformed root-medium pH, Ca, and Mg concentrations at 1, 4, 8, 12, and 17
weeks after planting in Part 1. .................................................................................... 106

. Degrees of freedom (d1), F-values (A), levels of significance (B), and mean
square of error a and error b from the analysis of variance for the log(observed +

S. 7' f‘ 1" a n 1"

10.

11.

12.

13.

14.

APPENDIX B

. Macronutrient information for Champion water-soluble fertilizers. ......................... 144

Total nutrient concentration supplied by Champion water-soluble fertilizer at an
N concentration of 200 mg-L". .................................................................................. 144

Macronutrient information for Greencare water-soluble fertilizers ........................... 145

Total nutrient concentration supplied by Greencare water-soluble fertilizer at an
N concentration of 200 mg-L". .................................................................................. 145

Macronutrient information on Masterblend water-soluble fertilizers. ....................... 146

Total nutrient concentration supplied by Masterblend water-soluble fertilizer at
an N concentration of 200 mgL". ............................................................................. 147

Macronutrient information on Peters Professional water-soluble fertilizers. ............ 148

Total nutrient concentration supplied by Peters Professional water-soluble
fertilizer at an N concentration of 200 mg-L". ........................................................... 149

Macronutrient information on Peters Excel water-soluble fertilizers. ....................... 150

Total nutrient concentration supplied by Peters Excel water-soluble fertilizer at
an N concentration of 200 mg-L". ............................................................................. 150

Macronutrient information on Plantex water-soluble fertilizers. ............................... 151

Total nutrient concentration supplied by Plantex water-soluble fertilizer at an N
concentration of 200 mg-L". ...................................................................................... 151

Macronutrient information on Technigro water-soluble fertilizers. .......................... 152

Total nutrient concentration supplied by Technigro water-soluble fertilizer at an
N concentration of 200 mg-L". .................................................................................. 152

xiv

LIST OF FIGURES

Figure Page
SECTION I

1. Frequency distribution based on water pH; electrical conductivity (EC);
alkalinity, Ca, Mg, SO4-S, Na, and Cl concentrations; and the Ca : Mg ratio and
sodium adsorption (SAR) ratio. The Ca : Mg ratio was calculated independently
for each sample with Ca and Mg concentrations in mg-L". The SAR was
calculated independently for each sample with Eq. [1] using Ca, Mg, and Na
concentrations in meq°L". The number of samples in which SO,-S was
measured (2276) is less than the total sample number (4306) because only two
laboratories did SO4-S analysis. Average and median values for the data used

to make the graphs are found in Table 2. .................................................................... 16
2. Classification of the water samples using salinity hazard and sodium hazard
based on recommendations found in Allison et al., 1954. ......................................... 17
SECTION II

1. Expt. 1. The pH of peat amended with ground, pulverized, superfine, or
microfine dolomitic carbonate lime (CaCO3 MgC03), and analytical grade
CaCO3 incorporated at either 2.4, 4.8, or 7.2 kg/m’, respectively, and
measured over 21 days. Dotted lines ( """ ) indicate recommended acceptable
ranges for the SME (Warncke and Krauskopf, 1983). Statistical analysis is
presented in Table 3. .......................................................................... 39

2. Expt 1. Calcium and Mg concentrations of peat amended with ground or
superfine dolomitic carbonate lime (CaCO3 MgCO,) incorporated at either 2.4,
4.8, or 7.2 kg/m’, respectively, and measured over 21 days. Minimum
acceptable concentrations for Ca is 80 mg/liter and Mg is 30 mg/liter when
measured with an SME (W amcke and Krauskopf, 1983). Statistical analysis is
presented in Table 3. .......................................................................... 40

3. Expt. 2. Root-zone pH, EC, NO,-N, PO4-P, Ca, and Mg concentrations of
uncovered subirrigated hybrid impatiens with media containing the blended
PNC fertilizers Greencare I, Uni-mix Plus 11, and MSU I from planting until
day 14. The liming material used was a microfine dolomitic hydrated lime

XV

(CaOH2 MgO) incorporated at 1.5 kg/m’. Dotted lines ( """ ) indicate
recommended optimal concentration(s), the lower dashed line (---) indicates
acceptable concentrations for the SME (W arncke and Krauskopf, 1983).
Vertical error bars are mean separation using LSD ..................................... 41

. Expt. 2. Comparison of root-zone and top-layer electrical conductivity (EC)
for pots grown without and with an evaporation barrier averaged over media
containing three PNC fertilizers from Experiment 2. Dotted lines (""') indicate
recommended optimal concentration(s), and lower dashed lines (---) indicate
acceptable concentrations for the SME (W amcke and Krauskopf, 1983).
Statistical analysis is presented in Table 4 ................................................. 42

. Expt. 2. Root-zone pH and PO4-P concentrations in media containing GC I
with either a microfine dolomitic hydrated lime (CaOH2 MgO) incorporated at
1.5 ltg/m3 or a superfine dolomitic carbonate lime (CaCO3 MgC03)
incorporated at 4.5 or 7 .5 kg/m’. Dotted lines ( """ ) indicate recommended
optimal concentration(s), the lower dashed line (---) indicates acceptable
concentrations for the SME (Warncke and Krauskopf, 1983). Vertical error
bars are mean separation using LSD ....................................................... 43

. Experiment 3. Root-zone EC, PO4-P, Ca, and Mg concentrations of
subirrigated hybrid impatiens with media containing the blended PNC
fertilizers Greencare I, Greencare II, Greencare III, and MSU II from planting
until day 14. The liming material used was a microfine dolomitic hydrated
lime (CaOH2 MgO) incorporated at 1.5 kg/m’. Dotted lines ( """ ) indicate
recommended optimal concentration(s), the lower dashed line (---) indicates
acceptable concentrations for the SME (Warncke and Krauskopf, 1983).
Vertical error bars are mean separation using LSD ..................................... 44

SECTION III

. Average new shoot dry weight of the three water-soluble fertilizer (WSF)
treatments from impatiens at 4, 8, 12, and 17 weeks after planting. After each
harvest, remaining plants were pruned to the same point. Error bars were
calculated as 95% confidence intervals. Data represent only the new shoot
growth from the previous four-week period. .............................................................. 75

. Root-medium pH, electrical conductivity (EC), PO4-P, Ca”, Mg”, and SO4-S
concentrations in the root zone of plants grown with four irrigation-water
sources and three water-soluble fertilizers (WSF) between weeks 1 and 17.
Filled symbols are hydrated lime treatments and hollow symbols are carbonate
lime treatments. The dotted lines ("""") represent the recommended optimal
ranges the and dashed lines (----) represent the lower recommended acceptable
range for the saturated media extract (Warncke and Krauskopf, 1983).

xvi

Statistical analysis is presented in Table 2. Data are means of four samples at
each date ...................................................................................................................... 76

. The effect of root-medium pH on the tissue P of impatiens grown with four
irrigation-water sources and three water-soluble fertilizers (WSF) at 4, 8, 12,
and 17 weeks after planting. Filled symbols are hydrated lime treatments and
hollow symbols are carbonate lime treatments. The solid line (—) represents
the predicted tissue P content based on Eq. [1] and the dotted line ( """ ) represents
the minimum recommended tissue P content. R2 values were calculated as 1-
SSmidmfl/SSmected ml and remaining statistical analyses of the individual
parameters are presented in Table 3. Data are means of four samples at each
date. ............................................................................................................................. 77

. The effect of applied Ca2+ concentration on the tissue Ca of impatiens grown
with four irrigation-water sources and three water-soluble fertilizers (WSF) at 4,
8, 12, and 17 weeks after planting. The solid line (——-) represents the predicted
tissue Ca content based on linear regression analysis and the dotted line ("")
represents the minimum recommended tissue Ca content. R2 values were
calculated as l-SSmidud/SScmwed ml, and remaining statistical analyses of the
individual parameters are presented in Table 4. Data are means of four samples
at each date. ................................................................................................................. 78

. The effect of applied Mg2+ concentration on the tissue Mg of impatiens grown
with four irrigation-water sources and three water-soluble fertilizers (WSF) at 4,
8, 12, and 17 weeks afier planting. The solid line (—) represents the predicted
tissue Mg content based on linear regression analysis and the dotted line ("")
represents the minimum recommended tissue Mg content. R2 values were
calculated as 1-SS,,,sidu,,/SScorrected tom, and remaining statistical analyses of the
individual parameters are presented in Table 5. Data are means of four samples
at each date. ................................................................................................................. 79

. The effect of applied SO4-S concentration on the tissue S of impatiens grown
with four irrigation-water sources and three water-soluble fertilizers (WSF) at 4,
8, 12, and 17 weeks after planting. Filled symbols are hydrated lime treatments
and hollow symbols are carbonate lime treatments. The solid line (—-)
represents the predicted tissue S content based on Eq. [1] and the dotted line ("")
represents the minimum recommended tissue S concentration. R2 values were
calculated as 1-SS,,_.,idu,,/SSCO,Tectcd m], and remaining statistical analyses of the
individual parameters are presented in Table 6. Data are means of four samples
at each date .................................................................................................................. 80

SECTION IV

. New shoot dry weight of impatiens grown in six root media containing various
rates of hydrated dolomitic lime (Ca(Ol—I)2 and Mg(OH)2) with three nutrient

xvii

solution treatments at 4, 8, 12, and 17 weeks after planting in Expt. 1. After each
harvest, remaining plants were pruned to the same point. Data represent only the
new shoot growth from the previous four-week period. Error bars were
calculated as 95% confidence intervals for each nutrient solution. Data are
means of four samples at each date. ............................................................................ 109

. Root-zone pH, Ca2+, and Mg“ concentrations in plants grown in six root media
containing various rates of hydrated dolomitic lime (Ca(OH)2 and Mg(OH)2)
with three nutrient solutions between weeks 1 and 17 in Expt. 1. The dotted
lines ( """ ) represent the recommended optimal ranges and dashed lines (----) (if
present) represent the lower recommended acceptable range for the saturated
media extract (Warncke and Krauskopf, 1983). Error bars were calculated as
95% confidence intervals for each nutrient solution. Overall statistical analysis
is presented in Table 3. Data are means of four samples at each date. ...................... 110

. Root-zone pH, Ca2+, and Mg2+ concentrations in plants grown in two media
containing either hydrated dolomitic lime (Ca(OH)2 and Mg(OH)2) or carbonate
dolomitic lime (CaCO3 and MgCO,) with three nutrient solutions between
weeks 1 and 17 in Expt. 2. The dotted lines ( """ ) represent the recommended
optimal ranges and dashed lines (----) (if present) represent the lower
recommended acceptable range for the saturated media extract (Warncke and
Krauskopf, 1983). Error bars were calculated as 95% confidence intervals for
each nutrient solution. Overall statistical analysis is presented in Table 4. Data
are means of four samples at each date. ...................................................................... 111

. The effect of applied Ca2+ and Mg” concentration on the shoot-tissue Ca and
Mg of impatiens grown in six root media at 4, 8, l2, and 17 weeks after planting
in Expt. 1. The solid line (—) represents the predicted shoot-tissue Ca
concentration based on linear regression analysis. The r2 values were calculated
as 1-ss,,,,,u,./ss,,,,,,d ml, and remaining statistical analyses of the individual
parameters are presented in Table 5. Data are means of four samples at each
date. ............................................................................................................................. 112
. The effect of applied Ca2+ and Mg2+ concentration on the shoot-tissue Ca and
Mg of impatiens grown in two root media containing either hydrated dolomitic
lime (Ca(OH)2 and Mg(OH)2) or carbonate dolomitic lime (CaCO3 and MgCO3)
at 4, 8, 12, and 17 weeks afier planting in Expt. 2. The solid line (———) represents
the predicted shoot-tissue Ca concentration based on linear regression analysis
from Fig. 4 and Table 5. Data are means of four samples at each date. .................... 113

SECTION V

. Root-medium pH of nine species grown with three nutrient solutions (NS). The
dotted lines represent the recommended optimal ranges for the 1:2 testing
method (Warncke and Krauskopf, 1986). Vertical error bars are mean
separation using LSD. Data are mean of three samples ............................................. 126

xviii

. The effect of applied Ca concentration on the shoot-tissue Ca of nine species at
35 days after planting. The solid line represents the predicted shoot-tissue Ca
concentration based on linear regression analysis. The statistical analysis of the
individual parameters are presented in Table 3. Data are mean of three samples. 127

. The effect of applied Mg concentration on the shoot-tissue Mg of nine species at
35 days after planting. The solid line represents the predicted shoot-tissue Mg
concentration based on linear regression analysis. The statistical analysis of the
individual parameters are presented in Table 3. Data are mean of three samples. 128

APPENDIX A

. Characterization of irrigation water pH from the 10 leading states in floricultural
production (United States Department of Agriculture Floriculture Crops 1994
Summary, Washington DC.) ..................................................................................... 133

. Characterization of irrigation water electrical conductivity (EC) (in dS-m") from
the 10 leading states in floricultural production (United States Department of
Agriculture Floriculture Crops 1994 Summary, Washington DC). .......................... 134

. Characterization of irrigation water alkalinity (in mg CaCO3/L) from the 10
leading states in floricultural production (United States Department of
Agriculture F loriculture Cr0ps 1994 Summary, Washington DC). .......................... 135

. Characterization of irrigation water calcium (in mg-L") from the 10 leading
states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC). ............................................. 136

. Characterization of irrigation water magnesium (in mg-L") from the 10 leading
states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC). ............................................. 137

. Characterization of irrigation water sulfate (in mg-L") from the 10 leading states
in floricultural production (United States Department of Agriculture Floriculture
Crops 1994 Summary, Washington DC). ................................................................. 138

. Characterization of irrigation water sodium (in mg'L") from the 10 leading
states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC). ............................................. 139

. Characterization of irrigation water chloride (in mg-L") from the 10 leading

states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC). ............................................. 140

xix

9. Characterization of irrigation water boron (in mg-L") from the 10 leading states
in floricultural production (United States Department of Agriculture F loriculture
Crops 1994 Summary, Washington D.C.). ................................................................. 141

10. Characterization of irrigation water Ca : Mg ratio from the 10 leading states in
floricultural production (United States Department of Agriculture F loriculture
Crops 1994 Summary, Washington DC). ................................................................. 142

11. Characterization of irrigation water sodium adsorption ratio (SAR) from the 10

leading states in floricultural production (United States Department of
Agriculture Floriculture Crops 1994 Summary, Washington DC). .......................... 143

XX

INTRODUCTION

Introduction

Historically, the switch from field soils to soilless root media in ornamental plant
production occurred due to the difficulty in obtaining uncontaminated field soil with the
prOper balance of physical and chemical properties and the improved aeration and
drainage provided by coarser soilless root media. Soilless root media can be leached
frequently, are difficult to over water, and were designed specifically for automated
irrigation system (drip irrigation) which are not uniform in the application of irrigation
water and fertilizer salts. It was not uncommon for root-medium pH and nutrient
concentrations in both the root medium and plant tissue to be managed using high
leaching rates ( > 50%) and high fertilizer concentrations (N at 300 to 400 mg-L“) applied
with every irrigation.

It is no longer acceptable to manage root-medium pH and macronutrient
concentrations in the root medium and plant tissue with high WSF concentrations and
high leaching rates because of concerns about water, fertilizer, and chemical runoff into
the environment from greenhouses. Irrigation systems that minimize or eliminate water,
fertilizer, and chemical runoff into the environment currently exist. With the low- or
nonleaching irrigation systems, lower concentrations of fertilizer must be used (N at 150
to 200 mg-L") in order to prevent salt buildup in the medium (Yelanich and Biernbaum,
1993). It has been suggested that fertilization practices should be based on soil-test
nutrient concentrations attained for a given addition of fertilizer, liming material, and
irrigation water containing a known nutrient concentration in order to optimize root-

medium pH and macronutrient management of these low- and nonleaching irrigation

2
systems (Biernbaum, 1992; Vetanovetz and Knauss, 1988). However, these proposed

strategies have not been tested under controlled conditions.

A number of sources interact to affect the nutrient supply in container root media
throughout crOp production. However, these sources do not affect the nutrient supply
simultaneously or with equal intensity. This is especially true for Ca and Mg nutrition,
where the sources can include the irrigation-water source, root media, lime, preplant
nutrient charge fertilizers, and water-soluble fertilizers. Any discussion of Ca and Mg
nutrition in container root media also must include pH management because of the direct
or indirect effects that Ca and Mg sources have on pH. Finally, plant growth may directly
affect medium pH as well as Ca and Mg uptake. A better understanding of how these
sources interact is necessary to improve the recommendations for pH, Ca, and Mg
management of container-grown crops over a wide range of conditions using low- or
nonleaching irrigation systems. The objective of this study was to determine which
sources are important for pH, Ca, and Mg management, and how multiple sources that
supply Ca and Mg and affect pH interact during production to affect the overall pH, Ca,

and Mg management of a crop.

Literature Cited
Biernbaum, J.A. 1992. Root-zone management of greenhouse container-grown crops to control
water and fertilizer use. HortTechnology 2(1): 127-132.
Vetanovetz, RP. and J .F. Knauss. 1988. Water quality. Greenhouse Manager. 7(2):64-72.

Yelanich, M.V. and J .A. Biembaum. 1993. Root-medium nutrient concentration and growth of

poinsettia at three fertilizer concentrations and four leaching fractions. J. Amer. Soc. Hort.
Sci. 188:771-776.

SECTION I

GEOGRAPHICAL CHARACTERIZATION OF
GREENHOUSE IRRIGATION WATER

HortTechnology
Accepted for publication: 15 Oct. 1996

Geographical Characterization of Greenhouse Irrigation Water

William R. Argo' and John A. Biernbaum2

Department of Horticulture, Michigan State University, East Lansing, MI 48824—1325

Darryl D. Warncke3
Department of Crop and Soil Science, Michigan State University, East Lansing, MI
48824-1325

We acknowledge the Michigan Agricultural Experiment Station, the Western Michigan
Bedding Plant Association, Fafard Analytical Services, Scotts Analytical Services, Sun
Gro Analytical Services, and the Michigan State University Soil and Plant Nutrient
Testing Laboratory for supporting this research. The use of trade names in this
publication does not imply endorsement of the products named or criticism of similar
ones not mentioned.

‘ Graduate Research Assistant.

2 Associate Professor

3 Professor.

Research Update

Geographical Characterization of Greenhouse Irrigation Water

Additional index words. alkalinity, boron, calcium, chloride, electrical conductivity,

magnesium, pH, sodium, sodium-adsorption ratio, sulfate

Summary. Chemical analyses of 4306 randomly selected greenhouse water samples for
1995 from the United States and Canada were obtained from four analytical laboratories
and graphically characterized using a distribution analysis. For pH, EC, and nutrient
concentrations, a mean and median value and the percentage of samples with
concentrations above or below those generally considered acceptable are presented for all
samples and the 10 leading states in floricultural production. The median nutrient
concentrations were determined to be more representative of the type of water found
throughout the United States and Canada than that of the mean values because of the
unequal distribution of the data. The overall median water source had a pH of 7.1; an
electrical conductivity (EC) at 0.4 dS-m"; an alkalinity of 130 mg CaCO3/L; (in mg-L")
40 Ca, 11 Mg, 8 804-8, 13 Na, 14 Cl, 0.02 B, and <00] F; a Ca : Mg ratio of 3.2 and a
sodium adsorption ratio (SAR) of 0.7. The information presented characterizes irrigation
water and may assist in the development of more refined fertilizer recommendations for

greenhouse crop production.

Several limited studies have been conducted to quantify the nutrient content of
different irrigation water sources (IWS) in the United States. Ludwig and Peterson (1984)
conducted a study on greenhouse irrigation water, but the data were presented orally, not
published in a readily accessible journal. In this study, pH ranged from 3.3 to 10.4 (mean
7.6); electrical conductivity (EC), from 0 to 6.5 dS-m’l (mean 0.5 dS-m"); alkalinity, fi'om
2 to 575 mg CaCO3/L (mean 147); (in mg-L") Ca, from 0 to 440 (mean 60); Mg, from 0
to 300 (mean 20); Na, from 0 to 1150 (mean 35); and B, from 0 to 2.9 (mean 0.1), based
on 662 water samples. However, a large percentage of the samples (30%) came from
Ohio, which may have biased the results. Reddy et a1. (1996) found that only 11% of the
IWS tested contained sufficient concentrations of 804-8 (30 mg-L") recommended for
plant grth in container culture. Reddy (1996) determined that a large number of
samples from states along the Atlantic coast (72%), the northeast (88%), and in the
Pacific Northwest (83%) of the United States were found to have SO4-S concentrations <
10 mg-L", while states around the Great Lakes and Midwest tended to have a greater
number of samples with SO4-S concentrations between 10 and 20 mgL". The
concentrations of other nutrients were not reported in the last two studies.

Recommended or acceptable nutrient levels in irrigation water for greenhouse
crops have been defined (Table 1). Emphasis needs to be placed on designing a water-
soluble fertilizer program for container plant production based on a given medium and
IWS (Biernbaum, 1992; Vetanovetz and Knauss, 1988). For example, Argo and
Biembaum (1996) demonstrated that four IWS varying in alkalinity, Ca, Mg, and 804-8
content had a significant effect on root-medium pH and nutrient concentrations as well as
shoot-tissue nutrient concentrations with impatiens. Recognizing differences in irrigation
water between states or geographical regions is important when making recommendations

for the nutritional management of container-grown crops, but little information about

6
regional differences in water quality exists. The objective of this study was to

geographically characterize the irrigation water used in the greenhouse industry.
Materials and Methods

Analyses of 4306 randomly selected greenhouse water samples from 1995 were
obtained from three commercial laboratories (Fafard Analytical Services, Athens, Ga.;
Scotts Analytical Services, Allentown, Pa.; and Sun Gro Analytical Services, Warwick,
NY.) and one university laboratory (Michigan State University Soil and Plant Nutrient
Laboratory, East Lansing, Mich.). All four laboratories measured pH, EC, alkalinity,
NO,-N, PO4-P, K, Ca, Mg, Na, Cl, and B. Only Fafard and Sun Gro laboratories
measured 804-8. The possibility of fertilizer solutions being included in the samples was
reduced by removing any sample with NO3-N at >20 mg-L‘l and or PO4-P at >10 mg-L".
We could not account for duplicate analyses from the same source, the possibility that
greenhouse operations with a given type of water were more or less likely to submit water
samples for analyses, or account for changes in water quality from a single source over
time.

Mean and median values were calculated from the overall data set and on a state-
by-state basis. Data are presented from the 10 leading states in floriculture production
(United States Department of Agriculture Floriculture Crop Summary, 1994,
Washington, DC). These 10 states accounted for 70% of the wholesale value of
floriculture crops in 1994 and for 57% of the total number of samples. Five percent of
the samples came from Canada which were included in the overall mean and median
values. Only Ontario had enough samples (93) to be included with the state data. The
suggested nutrient ranges found in Rose et a1. (1995) were used as the comparative values
for the presented data, unless otherwise indicated, because it has been our experience that

the values from Peterson are the suggested ranges most often reported.

7
Frequency distributions were calculated from the data using arbitrary ranges that

are considered by the authors to have potential cultural significance. The ranges used
were 0.4 pH unit; 0.2 dS-m'l for EC; 40 mg'L'l for alkalinity, 20 mg-L'l for Ca, and 10
mg-L'l for Mg, SO4-S, Na, and C1. The Ca : Mg ratio was calculated using their
concentrations mg-L". Sodium adsorption ratio (SAR) was calculated as

Na

SAR =
[(Ca + Mg)/2]“2

 

from Allison et al. (1954), where Na, Ca, and Mg are in meq°L".
Results and discussion

The mean values calculated in this study were similar to those reported by Ludwig
and Peterson (1985). However, for many of the nutrients, the mean value was larger than
the median value, indicating an unequal distribution of the data caused by a large
proportion of the samples having relatively low concentrations, where as, a small number
of samples contained relatively high concentrations.

The pH of the water samples ranged from 2.7 to 11.3. The overall mean pH value
of all water samples was 7.0, while the overall median value was 7.1 (Table 2), and the
distribution was skewed (Fig. 1). F orty-four percent of the samples were within the
suggested range of 5 and 7 (Rose et al., 1995), while 53% of the samples were >7. Water
samples from North Carolina had the lowest median pH (6.7) and the Ohio and Illinois
samples had the highest median pH (7.4) (Table 2).

The EC of the water samples ranged from <0.01 to 9.8 dS-m". The overall mean
EC of all water samples was 0.6 and the overall median value was 0.4 (Table 2). Ninety-
six percent of the samples had an EC within the suggested range of <15 dS-m‘l (Rose et
al., 1995) and 71% had an EC <0.6 dS-m". Water samples from North Carolina had the
lowest median BC (0.2 dS°m") and the California samples had the highest median EC
(0.9 dS-m") (Table 2).

8
The alkalinity concentration of the water samples ranged from 0 to 1120 mg

CaCO3/L. The overall mean alkalinity of all water samples was 160 mg-CaCO3/L, the
overall median value was 130 mg-CaCO3/L (Table 2), and the samples were more
uniformly distributed over a wider range than any other factor analyzed (Fig. 1). Twenty-
two percent of the water samples contained a alkalinity concentration within the
suggested range of 40 to 100 mg-CaC03/L (Biernbaum, 1994; Rose et al., 1995). Water
samples from New Jersey and North Carolina had the lowest median alkalinity
concentration (90 mg CaCO3/L) and the Illinois and Michigan samples had the highest
median alkalinity concentration (200 mg CaCO3/L) (Table 2). Based on the similar
concentration of Na and Cl and low SAR value measured in the samples (Table 2), it is
likely that the major source of alkalinity comes from Ca and Mg salts.

The Ca concentration in the water samples ranged from 0 to 560 mg'L". The
overall mean Ca concentration of the water samples was 52 mg-L'l and the overall median
value was 40 mg-L'l (Table 2). Forty-four percent of the samples were within the
suggested range of 40 and 120 mg'L'I (Fig. 1) (Rose et al., 1995). Water samples from
North Carolina had the lowest median Ca concentration (14 mg-L") and the Illinois
samples had the highest median Ca concentration (74 mg-L") (Table 2).

The Mg concentration in the water samples ranged from 0 to 190 mg-L". The
overall mean Mg concentration of the water samples was 19 mg'L" and the overall
median value was 11 mg-L'l (Table 2). Seventy percent of the samples were within the
suggested range of 6 and 24 mg-L'l (Rose et al., 1995), but 48% of the samples contained
Mg at <10 mg'L'l (Fig. 1). Water samples from North Carolina had the lowest median
Mg concentration (3 mg-L") and the Illinois samples had the highest median Mg
concentration (36 mg-L") (Table 2).

The Ca : Mg ratio in the water samples ranged from <0.1 to 152. The overall

mean Ca : Mg ratio of the water samples was 5.0 and the overall median value was 3.2

9
(Table 2). Twenty seven percent of the samples had a Ca : Mg ratio of >5 (Fig. 1). Water

samples from Illinois had the lowest median Ca : Mg ratio (2.0) and the Texas samples
had the highest median Ca : Mg ratio (4.7) (Table 2).

The SO4-S concentration in the water samples ranged from 0 to 750 mg-L". The
overall mean SO4-S concentration of the water samples was 27 mg-L", while the overall
median value was 8 mg°L'1 (Table 2). F ifieen percent of the samples were within the
suggested range of 30 and 80 mgL" (Fig. 1) (Reddy et al., 1994; Rose et al., 1995).
Water samples from North Carolina had the lowest median SO4-S concentration (<1
mgL") and the Ohio samples had the highest median SO4-S concentration (23 mg-L").
These data support the conclusion of Reddy (1996) that a majority of the water sources in
the United States (77%) are low in SO4-S (Table 2), but that states around the Great
Lakes (IL, MI, OH) tend to have greater SO4-S concentrations than those states on the
East Coast of the United States (FL, NC, NJ, NY, PA).

The Na concentration in the water samples ranged from 0 to 2500 mg-L". The
overall mean Na concentration of the water samples was 33 mg-L'l and the overall
median value was 13 mg-L'l (Table 2). Eighty-three percent of the samples were below
the suggested maximum concentration of 50 mg-L'l (Rose et al., 1995), with 41% of the
samples containing Na at <10 mg-L’l (Fig. 1). Water samples from Florida had the lowest
median Na concentration (8 mg'L") and the California samples had the highest median
Na concentration (49 mg'L") (Table 2).

The SAR concentration in the water samples ranged from 0 to 280. The overall
mean SAR of the water samples was 2.6 and the overall median value was 0.7 (Table 2).
Ninety-two percent of the samples were below the suggested maximum SAR of 4 (Fig. 1)
(Rose et al., 1995) and 62% of the samples had an SAR <1. Water samples from Florida
and Michigan had the lowest median SAR (0.4) and the California samples had the
highest median SAR (1.6) (Table 2). Based on recommendations from Allison et a1.

10
(1954), most of the water samples had a low potential for SAR hazard, but medium to

high potential for salinity hazard (Fig. 2).

The C1 concentration in the water samples ranged from 0 to 1480 mg-L“. The
overall mean Cl concentration of the water samples was 33 mgL", the overall median
value was 14 mg-L’l (Table 2), and the distribution was similar to that of Na (Fig. 1).
Ninety-seven percent of the samples were below the suggested maximum concentration
of 140 mg-L'l (Rose et al., 1995), with 40% of the samples containing Cl at <10 mg-L".
Water samples from North Carolina had the lowest median Cl concentration (6 mg-L")
and the California samples had the highest median Cl concentration (43 mg'L") (Table
2).

The B concentration in the water samples ranged from 0 to 11.7 mg-L". The
overall mean B concentration of the water samples was 0.22 mg-L'1 and the overall
median value was 0.02 mgL‘l (Table 2). Ninety-seven percent of the samples were
below the suggested maximum concentration of 1.0 mg~L'l (Rose et al., 1995) and 39% of
the samples contained B at <0.01 mg-L". However, the potential for B toxicity in certain
species may be at a much lower concentration. For example, Fafard Analytical Services
suggests that B at >0.4 mg-L'l may produce toxicity symptoms (W. McElhannon, Fafard
Analytical Services, personal communications). Overall, 8% of the samples contained B
at >0.4 mg-L", and within the individual states, ranged from <1% in the Florida samples
to 30% in the California samples (Table 2). Water samples from Pennsylvania had the
lowest median B concentration (0.01 mg-L") and the California samples had the highest
median B concentration (0.2 mg-L") (Table 2).

The F concentration in the water samples ranged from 0 to 8.3 mg-L". The
overall mean F concentration of the water samples was 0.15 mg-L" and the overall
median value was <0.01 mg'L" (Table 2). Ninety percent of the samples were below the

suggested maximum concentration of 1.0 mg'L'l (Rose et al., 1995) and 89% of the

11
samples contained F at <0.01 mg-L". As with B, the potential for F toxicity in certain

species may be at a much lower concentration, but the data indicates that F is either

present at concentrations above the suggested maximum concentration (>1.0 mgL") or is

absent from the water. All states contained some samples with F above the maximum

suggested concentration, but the median value for each state was <0.01 mgL".
Conclusion

The suggest range for IWS pH and alkalinity is 5 to 7 and 40 to 100 mg CaCO3/L,
respectively. In our opinion, IWS outside these ranges are not detrimental to plant
growth as long as the pH of the medium is maintained within an acceptable range. Argo
and Biembaum (1996) demonstrated that IWS alkalinity, not pH, is the primary factor
influencing medium pH management. Calcium, Mg, and 804-8 concentrations also are
important factors for characterizing irrigation water. However, these nutrients can be
supplemented or the proper balance obtained with the addition of water-soluble fertilizers
containing Ca, Mg, or SO4-S. Sodium, Cl, B, or F in irrigation water can create
nutritional problems for greenhouse crops, but a relatively small number of samples
contained these ions at potentially toxic levels.

Using these data, greenhouse operators can characterize a given water source and
how it compares to other water sources being used by the greenhouse industry. These
data also may be helpful in determining research priorities in the area of water quality for
greenhouse crop production. As the greenhouse industry changes to low- and
nonleaching irrigation systems, understanding differences in IWS is one key in the
development of more refined state and regional fertilizer recommendations for

greenhouse crop production.

1 2
Literature Cited

Allison, L. E., L. Bernstein, CA. Bower, J. W. Brown, M. Fireman, J.T. Hatcher, HE. Hayward,
G.A. Pearson, RC. Reeve, L.A. Richards, and L. V. Wilcox. 1954. Saline and alkali soils, p.
69-82. In: LA. Richards (ed.). United States Dept. Agr. Handbook No. 60.

Argo, WR and J.A. Biembaum. 1996. The effect of lime, irrigation-water source, and water-
soluble fertilizer on the pH and macronutrient management of container root media with
impatiens. J. Amer. Soc. Hort. Sci. 121(3):442-452.

Biernbaum, J.A. 1992. Root-zone management of greenhouse container-grown crops to control
water and fertilizer use. HortTechnology 2(1): 127-132.

Biernbaum, J.A. 1994. Water quality, p. 65-75. In: H. Tayama, T. Roll, and M. Gaston (eds.).
Tips on growing bedding plants. Ohio Florists' Assoc. Columbus, Ohio.

Gabriels, R 1978. The effect of irrigation water quality on the growing medium. Acta
Horticulturae. 82:201-212.

Ludwig, LS. and J.C. Peterson. 1984. An assessment of the chemical properties of water from
floriculture industry firms throughout Ohio and the United States. HortScience 19(3):521.
(Abstr.)

Reddy, SK MA. Madore, and PA. King. 1994. Survey of sulfur levels in greenhouse irrigation
waters. HortScience 29(5):503. (Abstr.)

Reddy, SK. 1996. Sulfur on tap. Greenhouse Grower. 14(1):58-60.

Rose, M.A., J. Peterson, and L. Kramer. .1995. The Ohio State University water quality
assessment program, p. 13-15. In: M.A. Rose and J .A Chatfield (eds). Ornamental plants: A
summary of research 1993-1994. Ciro. 142. Ohio Agr. Res. Development Center. Wooster,
Ohio.

Vetanovetz, RP. and J.F. Knauss. 1988. Water quality. Greenhouse Manager 6(12):64-72.

13

Table 1. Suggested minimum (Min) and maximum (Max) acceptable pH, electrical
conductivity (EC), alkalinity, nutrient concentration and sodium adsorption ratio (SAR)
for irrigation water used for greenhouse plant production. Units of measure are EC,
dS-m"; alkalinity, mg CaCO3/L; Ca, Mg, SO4-S, Na, Cl, B, and F, mg'L".

 

 

Biembaum Fafard Gabriels Nelson Rose et a1. Scotts Sungro
(1994)‘ (1996)y (1978) (1991)‘ (1995) (1996)" (19%)"
Min Max Min Max Min Max Min Max Min Max Min Max Min Max
pH 5.5 7.0 5.0 7.0 NA NA NA NA 5.0 7.0 NA NA 5.0 7.5
EC 0.2 0.8 0 1.0 0 0.85 0 0.75 0 1.5 0.2 1.3 0 1.0
Alkalinity 40 160“ 0 100 NA 200 0 40 0 100 40 150' 75 150 ‘
Ca 25 75 40 120 0 120 NA NA 40 120 25 100 40 80
Mg 10 30 6 24 0 25 NA NA 6 24 15 50 20 40
804-8 0 40 NA NA NA NA NA NA 0 80 NA NA 30 60
Na 0 20 0 50 NA NA 0 70 8 50 0 50 0 80
Cl 0 20 0 20 0 70 0 100 0 140 0 70 0 80
B 0 0.1 0 0.5 ' 0 0.75 0 1.0' 0.2 0.8 0 0.5 ' 0 0.5
F 0 0.1 0 0.75 ' 0 1.0 0 0.5 ' 0 1.0 0 1.0 ' 0 1.0
SAR NA NA 0 4 NA NA NA NA 0 4 NA NA NA NA

 

"A Not available

‘ Suggested target values from water analysis. A broader range of acceptable values was also presented.

’ Fafard Analytical Services, Athens. Ga.

‘ Suggested concentrations at which no nutritional problem should occur.

"’ Scotts Analytical Services, Allentown, Pa.

" Sun Gro Analytical Services, Warwick, N.Y.

“ Average suggested alkalinity concentration. The actual acceptable suggested alkalinity concentrations are dependent on the
container size. With plugs (in mg CaCO3/L), 40 to 80; while with 15-cm pots, 120 to 180.

' Average suggested alkalinity concentration. The actual acceptable suggested alkalinity concentrations are dependent on the
container size. With plugs (in mg CaCO3/L). 40 to 120; bedding flats, 40 to 140; 10- to 12-cm pots and large bedding flats, 40 to
160; and lS-cm pots or larger, 60 to 200.

' If plugs are grown, alkalinity values on the lower end of the range are suggested.

' The concentration that can cause toxicity in certain crops may be much lower.

14

Table 2. Geographical characterization of the average and median pH, electrical
conductivity (EC) alkalinity, water-soluble nutrient concentrations, Ca : Mg ratio,
and soditnn adsorption ratio (SAR) measured in greenhouse irrigation water from the
United States and Canada. Water Ca Mg ratio was calculated using the
concentrations of those nutrients in mg-L" and SAR was calculated from Eq. [1] using
nutrient concentrations in meq~L“. The number of samples in which SO,-S was
measured is less than the total sample number because only two laboratories did 80,-

 

 

 

S analysis.

Total CA FL TX MI OH NY PA NJ NC IL ON
Sample No.‘ 4306 329 280 289 342 118 211 247 92 375 192 101
(504-5 NO.) (2276) (123) (181) (181) (201) (50) (111) (111) (39) (206) (55) (93)

pH
Average 7.0 7.1 7.0 7.1 7.1 7.3 7.1 7.0 6.8 6.6 7.1 6.9
Median 7.1 7.1 7.2 7.2 7.3 7.4 7.2 7.0 7.0 6.7 7.4 7.0
< 5.0y 3% 2% 5% 2% 1% 1% 1% 1% 8% 5% 6% (1%
> 7.0 55% 63% 63% 60% 68% 72% 65% 51% 50% 36% 63% 41%
Electrical conductivity (dS'm")
Average 0.6 1.0 0.4 0.8 0.6 0.6 0.5 0.6 0.4 0.3 0.7 0.7
Median 0.4 0.9 0.4 0.6 0.6 0.6 0.4 0.4 0.3 0.2 0.7 0.5
> 1.5 4% 20% 1% 8% 3% 4% 2% 6% 3% 1% 2% 10%
Alkalinity (mg CaC03/L)
Average 160 170 140 180 200 190 160 140 100 120 220 170
Median 130 150 140 170 200 160 140 120 90 90 200 170
< 40x 18% 20% 12% 10% 8% 9% 11% 20% 27% 28% 13% 8%
> 100 61% 63% 70% 71% 77% 66% 73% 59% 47% 49% 72% 66%
Calcium (mg-L")
Average 52 78 58 64 69 73 58 54 34 25 66 ' 78
Median 40 61 46 61 69 71 45 42 23 14 74 66
< 40 50% 38% 41% 40% 26% 30% 41% 49% 69% 77% 28% 33%
> 120 6% 22% 7% 10% 8% 9% 3% 8% 3% < 1% 5% 14%
Magnesium (mg'L")

Average 19 34 13 15 22 24 15 15 10 6 32 21
Median 11 31 10 8 22 15 11 ll 7 3 36 19
< 6 33% 9% 29% 34% 8% 10% 19% 28% 49% 73% 10% 13%
> 24 26% 63% 13% 20% 43% 37% 16% 21% 9% 4% 63% 30%

 

15

Table 2. (Cont.)

 

Sulfate (mg-L")

Average 27 33 16 42 30 74 27 40 14 4 74 35

Median 8 17 3 21 20 23 8 21 10 0 20 10

< 30" 76% 69% 90% 59% 63% 54% 83% 60% 85% 98% 60% 83%

> 80 8% 14% 5% 16% 5% 20% 6% 13% <1% <1% 29% 10%
Sodium (mg-L")

Average 33 63 16 64 27 33 24 40 20 30 31 28

Median 13 49 8 30 9 17 14 11 11 9 15 11

> 50 17% 48% 8% 32% 12% 18% 12% 13% 10% 15% 17% 8%
Chloride (mg-L")

Average 33 62 26 58 27 32 34 63 20 18 28 44

Median 14 43 12 35 16 17 19 14 15 6 17 14

> 140 3% 8% 3% 9% 2% 3% 4% 3% <1% 1% 3% 7%
Boron (mg-L")

Average 0.22 0.67 0.03 0.17 0.79 0.09 0.06 0.08 0.19 0.18 0.16 0.10

Median 0.02 0.18 0.02 0.06 0.04 0.03 0.01 0.02 0.02 0.01 0.06 0.02

>10 3% 15% <1% 2% 1% 2% <1% 1% 3% 4% 1% 4%

> 0.4" 8% 30% < 1% 10% 9% 3% 2% 4% 7% 12% 14% 8%
Fluoride (mg-L")

Average 0.15 0.04 0.15 0.25 0.13 0.55 0.10 0.04 0.07 0.23 0.13 0.13

Median <0.0 <0.0 <0.0 <0.0 <0.0 <0.0 <0.0 <0.0 <0.0 <0.0 <0.0 <00

1 1 l 1 1 1 1 1 1 1 1 1
> 1.0 10% 2% 12% 17% 11% 35% 8% 4% 6% 10% 10% 13%
CazMg ratio
Average 5.0 2.9 8.5 7.2 3.7 4.4 4.5 4.5 5.5 6.8 2.6 4.2
Median 3.2 2.3 3.9 4.7 3.2 3.5 3.9 3.5 3.4 3.3 2.0 3.3
Sodium-adsorption ratio (SAR)

Average 2.6 2.5 0.7 5.7 1.7 1.4 1.4 3.7 3.3 3.4 2.8 1.8

Median 0.7 1.6 0.4 1.2 0.4 0.7 0.7 0.6 0.6 0.8 0.6 0.5

> 4 9% 11% <1% 21% 7% 7% 6% 9% 11% 14% 6% 4%

 

CA, California; FL, Florida; TX, Texas; MI, Michigan; OH, Ohio; NY, New York; PA, Pennsylvania; NJ. New Jersey; NC.
North Carolina; IL. Illinois; and ON, Ontario, Canada.

‘ Sample number. Values inside parentheses are the SO,-S sample number.

’ Acceptable pH, EC. nutrient ranges, and SAR for irrigation water were obtained from Rose et al. (1995) unless otherwise noted.

‘ Minimum alkalinity concentrations obtained from Biembaum (1994).

" Minimum 804-8 concentrations obtained from Reddy et a1. (1995).

" Maximum B concentrations obtained from W. McElhannon, Fafard Analytical Services. personal communications

16

 

30 30
25 4 9” EC - 25

20 - I I (dS'mJ) , 20
15 1 r 15
10 -‘ r10
5 r r 5
o .. _ 0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

QtQNQQtQNQQtQNN N v 0. 00. O. N. V. co. 0
VV'IDIDCQONNQQQaQ O O O o ‘- F' V" F ‘—
Vééédééééééééé" v ~ 4. «3. «3. <5. oi 4. "
'Y'WMQOQNNQQQ O o O o '- F P
so so
25, Alkalinity Ca t25
20 . (mg CaCO,/L) (mg-L") _ 20
15+ r15
10- ~10
5- —s
0‘ —o
assass§§§§§8988-asaass
V ' .. . . . A V . I A
8 grasses 298 .3.33
’360 so?
2: 50- Mg SO,-S»soa\,
6‘ 4° ‘ ("‘9’“) <mg~L") : 4° 6‘
5 30- +305
3 20+ r203,
gro- Hog
LL 0.1 LL
gasessesaggoasess s
ease seas ‘
50
Na
40 i (mg-Li) (mg L.) - 40
301 ~30
20] +20
10. r10
-0
889882 s§§
assessesa ‘
~— —i ~--7o
SARleo
[50
[40
lso
l [20
11-7-3°
.3 A

 

Fig. 1. Frequency distribution based on water pH; electrical conductivity (EC); alkalinity,
Ca, Mg, SO4-S, Na, and Cl concentrations; and the Ca : Mg ratio and sodium adsorption
(SAR) ratio. The Ca : Mg ratio was calculated independently for each sample with Ca and
Mg concentrations in mg°L". The SAR was calculated independently for each sample
with Eq. [1] using Ca, Mg, and Na concentrations in meq-L". The number of samples in
which SO4-S was measured (2276) is less than the total sample number (4306) because
only two laboratories did SO4-S analysis. Average and median values for the data used
to make the graphs are found in Table 2.

l7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a a?

I <

5 co

> V

.9

r2 \ E
(U .C

c

E E” .9

E ‘5.

.2 \ 5

ii 5 s
8

2 ‘P

N E

.2

'o

533 o

(0

Low Medium High Very high
Salinity hazard

Fig. 2. Classification of the water samples using salinity and sodium hazard based on
recommendations found in Allison et al., 1954.

SECTION II

AVAILABILITY AND PERSISTENCE OF MACRONUTRIENTS
FROM LIME AND PREPLANT NUTRIENT CHARGE
F ERTILIZERS IN PEAT-BASED MEDIA

Journal of the American Society for Horticultural Science
Accepted for publication: 9 Oct. 1996
Published: May 1996 [121(3):453-460]

Availability and Persistence of Macronutrients from Lime and Preplant Nutrient

Charge Fertilizers in Peat-Based Root Media

William R. Argol and John A. Biembaum2

Department of Horticulture, Michigan State University, East Lansing, MI 48824-1325

Received for publication 17 Apr. 1995 . Accepted for publication 9 Oct. 1995 . We
acknowledge the support of the Michigan Agricultural Experiment Station, the Western
Michigan Bedding Plant Association, and the Gloeckner Foundation. The use of trade
names in this publication does not imply endorsement of the products named or

criticism of similar ones not mentioned.

' Graduate Research Assistant.

2 Associate Professor.

Abbreviations: EB, evaporation barrier; GC 1, Greencare fertilizer I; GC 11,
Greencare fertilizer H; GC III, Greencare fertilizer III; PNC,
preplant nutrient charge; RO, reverse osmosis; SME, saturated

media extract; UM, Uni-mix Plus H.

18

19

Soils-Plant-Water relationships
Availability and Persistence of Macronutrients from Lime and Preplant Nutrient
Charge Fertilizers in Peat-Based Root Media
Additional index words. calcium, evaporation barrier, fertilizer salt stratification,
magnesium, nitrogen, phosphorous, potassium, soilless
media, subirrigation
Abstract. Using incubation and container culture with subirrigation for up to 28 days,
three experiments were conducted with six liming materials of different particle sizes
and six blended preplant nutrient charge (PN C) fertilizers. Liming material, particle
size, and incorporation rate had an effect on the initial pH (3.5 to 6.1) and the final
stable pH (4.8 to 7.8) with one type of Canadian Sphagnum peat that did not contain an
incorporated PNC. Saturated media extract (SME) Ca and Mg concentrations were
<25 and 15 mg/liter, respectively, for both pulverized and superfine dolomitic lime at
incorporation rates up to 7.2 kg/m’. For the blended PNC fertilizers in media
containing lime, initial electrical conductivity (EC) and SME nutrient concentrations
ranged from (EC) 1.0 to 2.9 dS/m, (mg/liter) 60 to 300 N, 4 to 105 PO4-P, 85 to 250
K, 120 to 400 Ca, and 60 to 220 Mg. However, within two day, the rapid stratification
of fertilizer salts within the pot caused macronutrient concentrations to increase in the
top 3 cm of root medium (top layer) by an average of 180% and decrease in the
remaining root medium in the pot (root zone) by an average of 57% compared to that
measured in the medium at planting. Nutrient concentrations in the top layer continued
to increase even when those in the root zone fell below acceptable levels recommended
for an SME. The importance of fertilizer salt stratification within a pot lies in the

reduced availability of nutrients to the plant and illustrates the limited persistence of the

20
PN C fertilizers. Testing nutrients in container media several days after planting rather

than in freshly mixed media may be more representative of the starting point for a

nutritional management program.

Media pH must be managed carefully to control nutrient availability in container
root media (Peterson, 1981). Liming materials are added to container root media with
acidic peats to increase pH to a level more acceptable for growth (Nelson, 1991;
Peterson, 1981; Wamcke and Krauskopf, 1983; Williams et al., 1988b). The particle
size and incorporation rate of the limestone influence the pH attained at equilibrium
(Chapin, 1980; Gibaly and Axley, 1955; Schollenberger and Salter, 1943; Sheldrake,
1980; Williams et al., 1988b). Some information about the differences in lime
requirements of certain peats is also available (Argo and Biernbaum, 1994; Lucas et
al., 1975; Puustjarvi and Robertson, 1975; Rosenbaum and Sartain, 1982), as is
information about the rate of reaction of lime (Williams et al., 1988b) and the effect of
water alkalinity in conjunction with lime (Williams et al., 1988a). However, it is not
known how the particle size or grind of the materials incorporated influences the
resulting water-soluble Ca and Mg concentrations initially or affects the persistence of
these nutrient concentrations over time.

In general, unamended acidic peat-based root media do not contain sufficient
nutrients for plant growth (Hunt, 1988; Nelson, 1991). Current recommendations for
the incorporation of fertilizer materials other than limestone into root media before
planting include sources of N, PO4-P, K, Ca, Mg, SO4-S, and trace elements (Table 1).
These guidelines come from the early soilless container media recommendations,
including the Cornell Peat-lite media (Boodley and Sheldrake, 1972), the Pennsylvania

State University media (White, 1974), Glasshouse Crops Research Institute media

21
(Bunt, 1988), and floriculture textbooks (Nelson, 1991). The most commonly

recommended macronutrient fertilizers include Ca(NO3)2, KN O3, superphosphate or
triple superphosphate, and gypsum (Bunt, 1988; Nelson, 1991; Warncke and
Krauskopf, 1983). Commercially available preplant nutrient charge (PNC) fertilizers
are ground and preblended for particle size uniformity and sometimes mixed with
granular wetting agents to provide greenhouse and nursery operators with a complete
product (Table 2). In general, the nutrient content of the blended PNC fertilizers is
within the range of the original soilless container media recommendations found in
Table 1.

The N and K content of the lime and PNC fertilizers is small compared to the
total amount applied to a crop. For example, Yelanich (1991) found that a minimum of
1.0 to 1.5 g mineral N/pot was required to produce a poinsettia in a lS-cm-wide by 12-
cm—wide (1.3-1iter) pot in 16 weeks. An initial incorporation of 0.17 kg mineral N/m3
would supply 0.22 g mineral N to the 1.3-liter pot, or 15% to 22% of the total N
requirement. In comparison, Ca, Mg, PO4-P, and 804-8 content of the lime and PNC
fertilizers may represent a large percentage, in some cases up to 100% , of the total
amount applied to the crop. However, only limited information exists on the initial
water-soluble nutrient concentrations that can be expected from the incorporation of the
PNC fertilizers (Warncke and Krauskopf, 1983) or their persistence over time. The
type of limestone incorporated into the soilless media also may affect nutrient
availability and persistence of the PNC, since pH affects the water-soluble nutrient
concentration (Peterson, 1981), and the pH of a freshly mixed lirned peat-based
medium may take up to two weeks to reach equilibrium (Williams et al., 1988b).

It has been suggested that fertilization practices should be based on soil-test
nutrient concentrations attained for a given addition of fertilizer, liming material, and

irrigation water containing a known nutrient concentration (Biernbaum, 1992;

22
Vetanovetz and Knauss, 1988). However, these proposed strategies have not been

tested under controlled conditions. Since lime and PN C fertilizers contain the initial
fertilizer applied to a crop, they represent the starting point in any nutritional program.

The objectives of this research were to determine the concentration of water-
soluble nutrients that can be expected from the incorporation of limestone and
commercially available PNC fertilizers in peat-based root media initially and over time.

Materials and Methods

Experiments consisted of multiple lime or fertilizer treatments incorporated at
one or more rates with two to three replications at several sampling dates. Data were
analyzed as a single or multiple factorial at each sampling date using the analysis of
variance (ANOVA) procedure of SAS (SAS Institute, 1982). Medium electrical
conductivity (EC) and nutrient concentration data were transformed to log(observed +
1) for the ANOVA because of differences in sample variance between treatments.
Time was not included in the ANOVA of any experiment because of changing sample
variance. Statistical analysis of single-factor experiments is presented in the figures as
mean separation with least significant difference (LSD). Statistical analyses of
multifactor experiments are presented in tables.

Expt. 1. The liming materials included were ground, pulverized, superfine, and
microfme dolomitic carbonate lime (99.5 % CaCO3 MgCO,, National Lime and Stone,
Carey, Ohio) and analytical-grade CaCO3 (J .T. Baker, Phillipsburg, N.J.). These
designations represented the bulk particle size of each material (Schollenberger and
Salter, 1943). For example, 60% of ground limestone will pass through a 250- m
(#60) screen, 60% of pulverized limestone will pass through a 150- m (#100) screen,
60% of superfine limestone will pass through a 75- m (#200) screen, and 99% of
microfine limestone will pass through a 45- m (#325) screen. With the analytical
grade CaCO,, 100% passed a 150- m screen but < 60% passed a 75- in screen.

23
The five lime materials were incorporated into 14 liters of a long-fibered

Canadian Sphagnum moss peat with little dust (Fisons black bale professional grower
grade, Sun Gro Horticulture, Bellevue, Wash.) at three incorporation rates: 2.4, 4.8, or
7.2 kg/m3. Before the lime incorporation, the peat had a pH of 3.8 and contained <4
mg Ca/liter and <2 mg Mg/liter as measured with the saturated media extract (SME).
The dolomitic limestone added to the peat 0.5, 1.0, and 1.6 kg Ca and 0.3, 0.6, and
0.9 kg Mg, respectively, per m3. No other fertilizers were incorporated. The peat was
moistened with reverse osmosis (RO) purified water to a level equivalent to 80% to
90% of container capacity in a 15-cm pot, placed into plastic bags, and maintained at a
constant 20C in the laboratory. The bags were left open for gas exchange. Subsamples
were removed from the plastic bags at mixing and at 3, 7, 13, and 21 days after
mixing. The experiment consisted of the five limestone types incorporated at three
rates with two replications per treatment for a total of 30 samples at each sampling
date.

Experiments 2 and 3 were conducted at Michigan State University, East
Lansing, in a well-ventilated glass greenhouse with constant air circulation and cement
floors. The root medium used was a 60% (by volume) Canadian sphagnurn moss peat
(Fisons black bale professional grower grade, Sun Gro Horticulture, Bellevue,
Wash.)/20% perlite/20% rockwool (Partek North American, Inc., Brunswick, Ohio)
and contained 0.3 kg of a wetting agent (Aquagro "L," Aquatrols, Cherry Hill, NJ.)
per m3 in addition to the indicated PNC and lime treatments. Incorporation rates and
nutrient contents for the PNC fertilizers are presented in Table 2. After mixing, media
remained in plastic bags with the tops open to the air for gas exchange for two days
before the pots were filled. Hybrid impatiens plugs (Impatiens wallerana cv. Super
Elfin Violet) from a 512 plug tray were planted into 11.5-cm-tall by 11.5-cm-wide

(0.7-liter) plastic pots containing media with the lime and PNC treatments, placed onto

24
a flood subirrigation bench, and irrigated daily with R0 purified water (pH = 6.0, EC

= 0.1 dS/m, alkalinity to pH 4.0 of <20 mg CaCO,/liter, and 20 and 7 mg Ca and
Mg/liter, respectively). At a typical irrigation, the benches were filled in 2 min to a 2-
cm depth and allowed to drain, which took an additional 5 min.

At each sampling date, the top 3 cm of root medium (top layer) was removed
and sampled separately from the remaining root medium within the same pot (root
zone). Nutrients were sampled using the SME method with R0 purified water as the
extractant (Warncke and Krauskopf, 1983). Root-medium pH was measured in the
saturated paste before extraction, and EC and macronutrients were measured in the
extracted solution. Root-medium pH and NO,-N were measured with ion-specific
electrodes (Orion models 91-02 and 93-07, respectively, Orion Research, Cambridge,
Mass), EC was measured with a platinum electrode at a standard 25C (YSI model 32,
Yellow Springs Instruments, Yellow Springs, Ohio), PO4-P and Mg were determined
colorimetrically (Knudsen and Beegle, 1988; Mg-blue method, Technicon Instruments,
Tarrytown, N.Y., respectively), and K and Ca were determined by emission
spectrometry.

Expt. 2. This experiment consisted of a total of eight treatments, five of which
were sampled at 0, 2, 7, 14, 21, and 28 days after planting, and three of which were
sampled at 14 and 28 days after planting, with three replications per treatment at each
sampling date. Statistical comparisons were made by grouping specific treatments for
analysis.

Comparison 1: The three blended PNC fertilizers used were GC I (Greencare I,
Greencare Fertilizers, Chicago, 111.), UM (Uni-mix Plus 11, Scotts, Marysville, Ohio),
and MSU I (PNC fertilizer blended at MSU) incorporated at 3.9, 2.7, and 3.9 kg/m’,
respectively. In addition to the PNC, a dolomitic hydrated limestone (97%
CaOH2 MgO, National Lime and Stone, Carey, Ohio) was incorporated at 1.5 kg/m3 in

25
the three treatments, which supplied an additional 0.5 kg Ca and 0.3 kg Mg/m3 of

medium. The bulk particle size of the hydrated lime allowed 97% to pass a 45- m
(#325) screen. Root media were sampled initially and at 2, 7, 14, 21, and 28 days after
planting. The comparison consisted of three PNC fertilizers with three replications at
six sampling dates.

Comparison 2: An evaporation barrier was placed on pots containing the GC 1,
UM, and MSU I media and consisted of an 11.5-cm plastic cover with a 0.5-cm hole
melted in the middle for the plant stern and cut from the perimeter to the center so the
cover could be inserted after planting. Root media in the covered pots were sampled at
14 and 28 days after planting. The comparison of the uncovered and covered root-zone
nutrient concentrations was analyzed as a three-by-two factorial with three replications
at the two sampling dates. Top-layer data were analyzed as a single factorial, with
replication made across PNC treatments.

Comparison 3: The superfine dolonritic carbonate lime (CaCO3 MgCO,) from
Expt. 1 was incorporated at 4.5 or 7.5 kg/m3 with GC I at 3.9 kg/m’. The lime
treatments added 1.0 and 1.6 kg Ca and 0.6 and 1.0 kg Mg, respectively, per m3 of
root medium in addition to the nutrients supplied by the PNC. These two treatments
were compared to the GC I treatment containing the hydrated lime. Root media were
sampled initially and at 2, 7, 14, 21, and 28 days after planting, with three replications
per treatment at each sampling date.

Expt. 3. The four PNC fertilizers used were GC 1, GC 11, GC [11 (Greencare I,
II, and 111, respectively, Greencare fertilizers, Chicago, 111.), and MSU II (PNC
fertilizer blended at MSU) incorporated at 3.9, 6.2, 0.9, and 2.7 kg/m’, respectively.
In addition to the PNC, the same dolomitic hydrated lime (CaOH2 MgO) from Expt. 2
was incorporated at 1.5 kg/m3 in all treatments. Root media from the top layer and

root zone were sampled initially and at 2, 7, l4, and 21 days after planting. The

26
comparison consisted of four PN C fertilizers with three replications at five sampling

dates.
Results and Discussion

Expt. 1. Lime particle size and incorporation rate affected the initial and final
stable pH of one type of peat without a PNC (Table 3, Fig. 1), results similar to those
obtained by Williams et al. (1988b). With the ground and superfine dolomitic lime
treatments at incorporation rates up to 7.2 kg/m’, the water-soluble Ca and Mg
concentrations ranged from 4 to 32 mg/liter and 2 to 15 mg/liter, respectively, and are
below the acceptable recommended concentration for the SME (W amcke and
Krauskopf, 1983) (Table 3, Fig. 2). Incorporation rate and bulk particle size did not
consistently affect the water-soluble Ca or Mg concentration measured in the medium.
The continued reaction of the lime (increasing pH over time) did not influence the
water-soluble Ca or Mg concentrations in the peat.

Warncke and Krauskopf (1983) reported that 1 kg of dolomitic lime/m3
incorporated in a root medium increased the water-extractable Ca concentration by 110
mg/liter. At the incorporation rates used in this experiment (2.4, 4.8, and 7.2 kg/m’),
the expected SME Ca concentrations should have been 280, 520, and 800 mg/liter,
respectively. Although significant amounts of Ca and Mg probably are associated with
the lirned peat and may be available to the plant, these ions were not measured with the
standard SME procedure (W amcke, 1986).

Experiment 2. In general, initial pH and water-soluble nutrient concentrations
of root media containing GC 1, UM, and MSU I were at or above those considered
optimal for the SME (Warncke and Krauskopf, 1983) (Fig. 3, remaining data not
shown). In comparison, Argo (1993) reported that initial pH of five commercial peat-
based root media ranged from 6.0 to 6.6; EC, from 1.6 to 3.6 dS/m; and initial nutrient

concentrations, from (mg/liter) 65 to 180 N, 3 to 25 PO4-P, 70 to 328 K, 120 to 580

27
Ca, and 34 to 130 Mg. Thus, the PNC fertilizers used in this experiment contain

amounts of incorporated nutrient similar to those recommended for early soilless media
culture (Tables 1 and 2) (Boodley and Sheldrake, 1972; Bunt, 1988; Nelson, 1991;
White, 1974), and, except for PO4-P, the nutrient concentrations in the media with the
PNC fertilizers were similar to those measured in fresh commercial root media before
planting.

In addition to the lime, there are also recommendations for the water-soluble
nutrient concentrations that can be expected from the incorporation of gypsrnn,
superphosphate, Ca(NO,)2, and KNO3 (Warncke, 1976; Warncke and Krauskopf,
1983). Using MSU I as an example (Table 2) and not including the lime in the
calculation, the predicted water-soluble nutrient concentration would be (mg/liter) 150
N, 25 P, 105 K, and 270 Ca, as measured with the SME. The actual concentration of
nutrients measured in media containing MSU I was (mg/liter) 220 N, 105 P, 240 K,
and 170 Ca. Warncke (1976) used field soil in five of the six media with the
incorporated PNC fertilizers. Perhaps the absence of soil and the greater water-holding
capacity of the peat/rockwool/perlite medium used in this experiment affected the
partitioning between exchangeable, insoluble, and water-extractable nutrients, which
resulted in the difference between the predicted and measured nutrient concentrations.

The concentration of all nutrients tested in the root zone decreased rapidly
between planting and 14 days after planting (Fig. 3). Because of the limited amount of
plant growth during this period, the nutrients moved from the root zone to the root-
medium surface (Table 4, Fig. 4). Once the initial concentration of water-soluble
nutrients was reduced because of salt stratification, the residual material from the PN C
(if present) did not maintain the root-zone nutrient concentrations at levels acceptable

for plant growth.

28
The movement of fertilizer salts to the top layer with subirrigation is a

significant point of fertilizer salt removal from the root zone, similar to that of leaching
water from the bottom of the pot (Argo and Biernbaum, 1994; Argo and Biernbaum,
1995a). Fertilizer salt stratification within the pot is thought to be caused by
evaporation from the root-medium surface (Argo and Biernbaum, 1994; Argo and
Biernbaum, 1995a) or a water front moving into the root medium with each irrigation
(Yelanich, 1995). When the surface was covered with an evaporation barrier, the
stratification of fertilizer salts within the pot was less at days 14 and 28 compared to
that in uncovered pots (Table 4, Fig. 4.).

Another important aspect of fertilizer salt stratification within the pot may be in
the reduced availability of nutrients to the plant. In previous work with subirrigated
Easter lilies and poinsettias, Argo and Biembaum (1994, 1995a) found that nutrients
that moved to the top layer of the pot were less available to the plant than if the same
nutrients remained in the root zone, and the concentration of nutrients in the top layer
continued to increase even when root-zone nutrient concentrations were below
acceptable levels for an SME. However, in this experiment, the plants were able to
extract nutrients from the top layer later in crop development when nutrient
concentrations became limiting in the root zone, as illustrated by the decrease in
nutrient concentrations in the top layer of uncovered pots after day 14 (Fig. 4). There
was a thick mat of roots 0.5 to 1 cm below the root-medium surface by day 14 in the
uncovered pots.

The availability of nutrients contained in the top layer may be a result of
irrigation frequency. In this experiment, plants in 11.5-cm-tall pots were irrigated
daily, resulting in a high moisture content throughout the medium profile for the entire
experiment. In comparison, with Easter lilies and poinsettias, Argo and Biembaum

(1994, 1995a) used lS-cm-tall pots irrigated when the root medium reached a moisture

29
content of 25% to 35 % of the total water held at container capacity, and nutrients

contained in the top layer did not appear to be available to the plant. If the medium is
allowed to dry between irrigations, the top layer may not contain sufficient moisture for
root growth, rendering the nutrients contained in the top layer unavailable to the plant.
George (1989) found that container height influences water absorption with
subirrigation, which also may have influenced the availability of nutrients contained in
the top layer of the 11.5-cm-tall pots used in this experiment.

Irrigation method also may affect the persistence of the PNC fertilizers in the
root zone. Argo and Biembaum (1995a, 1995b) found that fertilizer salt stratification
also occurred with top-watered poinsettias grown with 33% and 25% leaching,
respectively. Because of the leaching effects of the water, nutrients contained in the top
layer provided a source of nutrients (buffering capacity) for the root zone for up to six
weeks once fertilization was stopped (Argo and Biernbaum, 1995b). Thus, the
persistence of PNC fertilizers with top-watering methods may be different than that
measured in this experiment with subirrigation.

The use of a microfine dolomitic hydrated lime (CaOH2 MgO,1.5 kg/m’)
compared to a superfine dolomitic carbonate lime (CaCO3 MgCO3, 4.5 or 7 .5 kg/m’)
did not affect either the initial concentrations of Ca or Mg or the persistence of these
ions in the root zone up to 28 days after planting (data not shown), even though more
Ca and Mg were added to the root medium containing the carbonate lime treatments
(1120 mg Ca and 680 mg Mg per pot at 7.5 kg/m’) than the same hydrated lime
treatments (350 mg Ca and 210 mg Mg per pot at 1.5 kg/m’). The initial pH of media
containing the hydrated lime was 6.0 and remained fairly stable for the entire
experiment (Fig. 5). In comparison, the initial pH of the media with the carbonate lime
was 4.5 and required 14 days to reach the same pH as the media containing the

hydrated lime. As in Expt. 1, the continued reaction of the carbonate lime (increasing

30
pH) did not affect medimn Ca and Mg concentrations measured with the SME. Instead,

the main effect of the different liming materials on nutrient availability from GC 1 was
due to pH effects on PO,-P solubility (Fig. 5).

The solubility of PO4-P can be based on medium pH, EC, and Ca concentrations
(Lindsay, 1979). Increasing the initial pH (as with hydrated lime) decreased the initial
concentration of water-soluble P (hydrated lime = 65 mg PO4-P/liter; carbonate lime
average = 125 mg PO4-P/liter) and the amount of P that moved to the top layer (data
not shown). The loss of PO4-P from the root zone into the top layer (or leached from
the pot) because of lower initial pH may affect the long-term availability of PO4-P.

Expt. 3. At the initial soil test, EC, PO4-P, Ca, and Mg concentrations (Fig. 6),
as well as NO3-N and K concentrations (data not shown) were at or above optimum
concentrations for an SME in media containing CC I and MSU II. In media containing
GC H, initial PO4-P concentrations were below acceptable levels for an SME because of
the limited solubility of the P source (steamed bone meal). Initial nutrient
concentrations in media containing GC III were within acceptable levels for an SME but
were lower than those of the other PNC fertilizers. The total amount of nutrients
incorporated with GC III was lower than that in the other PNC fertilizers (except for
Mg) (Table 2). In fact, GC III is similar in N, K, and 804-8 content to the
recommended initial nutrient content of several seedling media (Boodley and Sheldrake,
1972; Bunt, 1988; White, 1974), but with significantly lower PO4-P and Ca.

As in Expt. 2, the concentration of all nutrients tested in the root zone decreased
rapidly and, by day seven, were similar for NO3-N, K, Ca, and Mg in all treatments
(Fig. 6). There was a corresponding increase in the nutrient concentration in the top
layer (Fig. 6). As in Expt. 2, the nutrients in the top layer appeared to be available to
the plant later in the experiment, as illustrated by the decrease in nutrient concentrations

between 7 and 14 days after planting.

31
Reducing the incorporation rate or limiting the solubility of the nutrient also

affected the amount lost to the top layer. For example, decreasing the amount of PO,-P
incorporated into the medium by 50% (GC 1 vs. MSU II) decreased initial PO4-P
concentrations by 38% (Fig. 6). After 14 days, the concentration of PO4-P in the root
zone was above optimal levels for the SME with both PNC fertilizers, and the increase
in the concentration of PO4-P of media containing MSU II was less than that of media
containing GC 1. In another example, media containing GC I and GC 11 had similar
amounts of incorporated PO4—P (Table 2). Initial PO4-P concentrations of media
containing GC 11 were only 5% of the initial concentration of media containing GC I
(Fig. 6), and the corresponding increase in the top-layer PO4-P concentrations with GC
11 was less than with media containing GC 1. Soilless media have a limited ability to
retain PO4-P against leaching (Yeager and Barrett, 1985) and subirrigation or top
watering under production conditions (Argo, 1993), which may result in insufficient
PO4-P concentrations later in crop development. Limiting the solubility of the PO4-P
carrier (bone meal) may increase its persistence over time. However, there was some
marginal leaf necrosis observed 14 days after planting on the plants grown in media
containing GC 11, and the odor of the steamed bonemeal during formulation of the PNC
was objectionable (L. Metcalf, Greencare Fertilizers, Chicago, Ill. personal
communications).

Based on discussions with four commercial peat-based media suppliers, PNC
fertilizer incorporation rates from ten years ago were similar to those used in MSU
I/GC 1. Typical incorporation rates during the past two years for N, P, and K fertilizer
have been reduced by as much as half. If a complete water-soluble fertilizer is applied
on a constant basis starting at the initial irrigation, it is questionable whether the high

initial nutrient concentrations measured in media containing GC 1, GC 11, UM, MSU I,

32

or MSU II are necessary because of the rapid loss of nutrients from the root zone when
subirrigation was used.

In Expts. 2 and 3, the use of dolomitic hydrated lime (CaOH2 MgO) offered a
method of rapidly obtaining a root-medium pH of 6.0. At an incorporation rate of 1.5
kg of the hydrated lime per m3, initial pH was 6.0 and remained relatively stable for up
to 28 days in a peat/perlite/rockwool medium. In comparison, the initial pH of the
same medium containing up to 7.5 kg of superfine dolomitic carbonate lime
(CaCO3 MgCO,) per m3 was 4.6 and required up to 14 days to equilibrate to 6.0.

Hydrated lime has not been recommended for use as a preincorporated liming
material because of the potential for rapid conversion of NH, to toxic NH3 (Bunt, 1988;
Nelson, 1991) and damage to new roots (Bunt, 1988). There was no limitation in plant
growth caused by interactions with the hydrated dolomitic lime and PNC fertilizers
containing high amounts of N H4-N (UM containing urea formaldehyde and GC H
containing bonemeal) probably because the initial medium pH was kept below 7.0, as
recommended by Bunt (1988), with organic N fertilizers, and the root medium was
allowed to equilibrate for two days before planting.

Because of the highly reactive nature of hydrated lime in addition to the small
particle size of the material used, it is probable that most (> 95%) had reacted when the
equilibrium pH was obtained. Assuming that similar equivalents of lime are required to
obtain the same pH, 2.4 kg of the carbonate lime per m3 is required to obtain the same
pH as achieved by 1.5 kg of the hydrated lime per m3. Under the conditions of the
experiment, up to 5 kg of unreacted or residual carbonate lime per m3 may have
remained in the root medium when the equilibrium pH was reached. That unreacted
lime was present is further supported by the similarity of the Ca and Mg concentrations
in media containing either hydrated or carbonate lime in addition to PNC fertilizers

(Expt. 2), even though three times more Ca and Mg was incorporated with the

33

carbonate lime treatments. The effect of the presence or absence of residual lime on the
long-term pH, Ca, and Mg buffering capacity of a root medium requires further study.
Recognition of the rapid decrease in nutrient concentrations after planting is
important for the proper interpretation of root-medium analysis. When PNC fertilizers
have been incorporated, nutrient concentrations in fresh medium taken from a mixing
line or a bag will be higher than that of media placed in a container, irrigated, and
allowed to dry for several days before sampling. Moistening and incubating the media
for several days to two weeks in a closed container likely will give a better estimate of
the starting pH, but not EC or macronutrient concentrations. In our opinion, a sample

taken two to four days after planting is more representative of the starting point of a

nutritional program. Based on these experiments, the EC and nutrient concentrations of

media several days after planting likely will fall within the lower acceptable range for
nutrient concentrations based on the SME (W amcke and Krauskopf, 1983). However,
because of the preliminary nature of these experiments, specific grower
recommendations about PNC fertilizers, liming materials, rates, and sampling methods
cannot be made.

Literature Cited

Argo, W.R. 1993. The role of peat-based root media in water and fertilizer efficiency of
greenhouse crops. MS Thesis, Michigan State Univ., East Lansing.

Argo, W.R. and J.A. Biembaum. 1994. Irrigation requirements, root-medium pH and nutrient
concentrations of Easter lilies grown in five peat-based media with and without an
evaporation barrier. J. Amer. Soc. Hort. Sci. 119(6):1151-1156.

Argo, W.R. and J .A. Biembaum. 1995a. The effect of irrigation method, water-soluble
fertilization, preplant nutrient charge, and surface evaporation on early vegetative and root
growth of poinsettia. J. Amer. Soc. Hort. Sci. 120(2):163-169.

Argo, W.R. and J.A. Biembaum. 1995b. Nutrient levels and irrigation requirements of five

root media with poinsettia. HortScience 30(3):535-538.

34

Biernbaum, J.A. 1992. Root-zone management of greenhouse container—grown crops to control
water and fertilizer use. HortTechnology 2(1):127-132.

Boodley, J.W. and R. Sheldrake, Jr. 1972. Cornell Peat-lite mixes for commercial plant
growing. N .Y. College Agr. Info. Bul. 43.

Bunt, A.C. 1988. Media and mixes for container-grown plants. Unwin Hyman, London.

Chapin, J.K. 1980. The effect of fineness in limestone on the pH of 50:50 peat-vermiculite
mix. Benchmarks l(7):7.

George, R.K. 1989. Flood subirrigation systems for greenhouse production and the potential
for disease spread. MS Thesis, Michigan State Univ., East Lansing.

Gibaly, HE. and J.H. Axley. 1955. A chemical method for the rating of agricultural
lirnestones used as soil amendments. Soil Sci. Soc. Amer. Proc. 20:301-302.

Hawkes, G.R., D.B. Campbell, A.E. Ludwick, R.M. Millaway, and R.M. Thorup. 1985.
Western fertilizer handbook. 7th ed. Interstate, Danville, IL.

Knudsen, D. and D. Beegle. 1988. Recommended phosphorus tests, p. 12-15. In: W.C.
Dahnke (ed.). Recommended chemical soil test procedures for the north central region.
North Central Reg. Publ. 221.

Lindsay, W.L. 1979. Chemical equilibria in soils. Wiley, New York.

Lucas, RE, RE. Rieke, J.C. Shickluna, and A. Cole. 1975. Lime and fertilizer requirements
for peats, p. 51-70. In: D.W. Robinson and J.G.D. Lamb (eds.). Peat in horticulture.
Academic Press, London.

Nelson, P.V. 1991. Greenhouse operations and management. 4th ed. Prentice Hall,
Englewood Cliffs, NJ.

Peterson, J.C. 1981. Modify your pH perspective. Florist's Rev. 169(4386):34-35, 92-93.
Puustjarvi, V. and R.A. Robertson. 1975. Physical and chemical properties, p. 23-38. In:
D.W. Robinson and J.G.D. Lamb (eds). Peat in horticulture. Academic Press, London.
Rosenbaum, SE. and J.B. Sartain. 1982. Lime requirement of several soilless media. Proc.

Florida State Hort. Soc. 95:293-294.

SAS Institute, Inc. 1982. SAS user's guide and SAS statistical procedures. SAS Institute, Cary,

NC.

35
Schollenberger, OJ. and R.M. Salter. 1943. A chart for evaluating agricultural limestone. J.

Amer. Soc. Agron. 35:955-966.

Sheldrake, R. 1980. Lime quality and quantity study on peat-vermiculite. Benchmarks 1(7):6-7.

Vetanovetz, R.P. and J.F. Knauss. 1988. Water quality. Greenhouse Manager. 7(2):64-72.

Warncke, DD. 1976. Saturation extractable nutrient levels on six greenhouse soil mixes
equilibrated with four rates of fertilizer, p. 155. Agron. Abstr., Amer. Soc. Agron.,
Madison, WI.

Warncke, DD. 1986. Analyzing greenhouse growth media by the saturation extraction
method. HortScience 2 1 (2) :223-225.

Warncke, DD. and D.M. Krauskopf. 1983. Greenhouse growth media: Testing and nutrition
guidelines. Mich. State Univ. Ext. Bul. E-1736.

White, J.W. 1974. Dillon Research Fund, progress report on research at Penn. State. Penn.
Flower Grower Bul. 273:3-4.

Williams, B.J., J .C. Peterson, and JD. Utzinger. 1988a. Effects of dolomitic lime and alkaline
water in Sphagnum peat-based container growing media. HortScience 23:168-169.

Williams, B.J., J.C. Peterson, and J .D. Utzinger. 1988b. Liming reactions in Sphagnum peat-
based growing media. J. Amer. Soc. Hort. Sci. 113:210-214.

Yeager, T.H. and IE. Barrett. 1985. Phosphorus and sulphur leaching from an incubated
superphosphate-amended container media. HortScience 20:671-672.

Yelanich, M.V. 1991. Fertilization of greenhouse poinsettia to minimize nitrogen runoff. MS
Thesis, Michigan State Univ., East Lansing.

Yelanich, M.V. 1995. Modeling the concentration of nitrogen in the root zone of container

grown Chrysanthemums. PhD Diss., Michigan State Univ., East Lansing.

36

Table 1. Recommended preplant nutrient charge fertilizers and rates. The nutrient
content of the individual fertilizer salts was estimated from Hawkes et a1. (1985).

 

Cornell Cornell Pennsylvann Nelson GCRI-I GCRI-2
Peat-lite foliage ia State potting potting potting
A and B ‘ media 2 media ’ media " media " media “V

 

All incorporation rates in kgm‘3 of root media

 

0.9 KNO, 0.9 KNO, 0.6 KNO, 0.6 KNO,‘ 0.8 1010, 0.8 1010,
0.6 0-8.6-0 . 0.6 0-8.6-0 v 1.2 0-8.6-0 V 0.6 Ca(NO,)2 0,4 NH4N03 0.9 urea-

 

 

 

PNC 1.6 10-4-8“ 0.6 20-8-15u 0.3 MgSO,‘ 1.5 0-8.6-0v formaldehyde
fertilizers 1.5 0—8.6-0v
2.7 0-8.6-0
or
1.3 0-19.8-0’
0.9 gypsum
4.9 3.0 2.25 each 2.25 each
Lime 3.0 ground dolomitic dolomitic 6.0 dolomitic ground and ground and
rate limestone limestone limestone limestone dolomitic dolomitic
limestone limestone
kg nutrient per m3 of root medium
Total N 0.12 0.28 0.2 0.18 0.25 0.45
PO,-P 0.05 0.12 0.15 0.23 0.13 0.13
K 0.33 0.46 0.31 0.22 0.29 0.29
Ca 0.12 0.12 0.23 0.64 0.29 0.29
Mg 0.00 0.00 0.00 0.03 0.00 0.00
SO4-S 0.07 0.07 0.14 0.35 0.18 0.18
2 Boodley and Sheldrake, 1972.
y White, 1974.

x Nelson, 1991.

w Glasshouse Crops Research Institute (Bunt, 1988).

V N-P-K content of single superphosphate (3Ca(H2PO4)2 H20 + 7CaSO4 2H20 + 2HF).

U N-P-K content of blended fertilizer. The exact formulation of this fertilizer is unknown and is not included in the nutrient
content calculation for Ca, Mg. or 804-3.

1 The incorporation of these materials is optional (Nelson. 1991) but is included in the nutrient content calculations.

5 N-P-K content of triple superphosphate (10C a(llzPO4)2 H20 + 2HF).

r The lime recommendation is not included in the nutrient content calculation.

37

Table 2. Materials used to produce blended preplant nutrient charge (PNC) fertilizers and
estimation of the amount of each macronutrient supplied by the different PNC fertilizer
based on the recommended incorporation rate.

 

 

 

 

 

 

 

MSU l ’ MSU 11 ’ GC 1 " GC 11 " GC lll " UM "
KNO,
KNO3 KNO, KNO3 KNO3 (NH,)H2PO,,
Fertilizer Ca(NO,)2 Ca(NO,)2 Ca(NO,)2 Ca(NO,)2 KNO3 urea-
salts 0-19.8-0 V 0-19.8-0 V 0-19.8-0 V steamed- KHZPO4 formaldehyde
gypsum gypsum gypsum bone meal gypsum KZSO,
MgSO4 MgSO4 MgSO, gypsum MgSO, 0-19.8-0 "
MgSO4 gypsum
MgSO,
Rate (kg-m' 3.9 2.7 3.9 6.2 0.9 2.7
3
)
Elemental analysis (%)
Total N 4.4 6.3 4.4 3.2 4.0 10.0
PO,-P 6.2 4.5 6.0 3.9 1.3 4.4
K 5.7 8.3 5.5 3.6 11.6 4.2
Ca 12.9 11.4 8.6 3.7 6.0 4.0
Mg 0.8 1.1 0.7 0.5 3.0 2.5
SO,-S 5.7 4.9 5.6 3.9 8.8 7.0
kg nutrient per m3 of root medium
Total N 0.17 0.17 0.17 0.19 0.04 0.27
PO,-P 0.23 0.12 0.23 0.24 0.01 0.12
K 0.22 0.22 0.21 0.22 0.10 0.11
Ca 0.50 0.30 0.33 0.23 0.05 0.11
Mg 0.03 0.03 0.03 0.03 0.03 0.17
SO4-S 0.22 0.13 0.21 0.24 0.08 0.19

 

Z MSU l was 0.6 kg KNO3 and Ca(NO3)2, 1.2 kg 0-19.8-0 and gypsum, and 0.3 kg MgSO4 per m3 of media, respectively.
Y MSU II was 0.6 kg KNO3, Ca(NO3)2, 0-19.8-0, gypsum. and 0.3 kg MgSO4 per m3 of media, respectively.

X Greencare I, II, and 111, respectively, Greencare Fertilizers, Chicago, Ill.

W Uni-mix Plus 11, Peter s Fertilizer, Marysville, Ohio.

V N-P-K content of triple superphosphate (10Ca(H2PO4)2 21120 + 2HF).

38

Table 3. Summary of analysis of variance by sampling date of the effect of lime grind
and incorporation rate on the log(observed + l) transformed pH, Ca, and Mg
concentration.

 

 

 

Sampling day
pfl 0 3 7 13 21
Lime grind (LG) *Itllt *** *** *4”? *4!!!
Rate (R) #33 #8313 *4”: #** tit
LG x R ** *** * NS NS
S! 0.01 0.01 0.01 0.01 0.01
Ca/Mg
LG ***/*** NS/‘NS *Ill/NS ***/*** ***/**
R ***/*** *It/NS **/** ***/*** **/*
LG XR **/*** */NS **/** ***/*** **/*
s62 0.01/0.01 0.02/0.06 0.02/0.02 0.01/0.01 0.02/0.01

 

N5,’-"-'"Nonsignificant or significant at P 0.05, 0.01, or 0.001, respectively.
ZSquare root of the mean square error from the ANOVA of the transformed data.

Table 4. Expt. 2. Summary of analysis of variance by sampling date of the effect of an
evaporation barrier on the top layer and root zone log(observed + 1) transformed
electrical conductivity (EC) and macronutrient concentration.

EC NO3-N PO4-P K Ca Mg

 

 

 

 

 

Top Evaporation barrier: Day 14 ** M n tn u: n
Layer Evaporation barrier: Day 28 * NS ** * * NS
Day 14
Evaporation barrier (EB) *** *** * m: *n "a:
PNC fertilizer *** *** N5 M: an” an”
EB x PNC NS NS NS u * u
Root s} 0.02 0.08 0.16 0.04 0.01 0.04
zone Day 28
Evaporation barrier (EB) *** ** *** *H at“ us
PNC fertilizer * *H an: :- * NS
EB x PNC NS ** NS NS NS NS
s} 0.03 0.10 0.03 0.06 0.05 0.06

 

NS-i-uainNonsignificant or significant at P 0.05, 0.01, or 0.001, respectively.
ZSquare root of the mean square error from the ANOVA of the transformed data.

39

 

 

 

 

Root-medium pH
wammwmwhmmumwhmmwmo

 

 

1 1 1 l r l r l L l

 

o 4 8 12 16 20
Days from mixing

 

I Pulverized 0 Ground
0 Superfine v Microfine
. Analytical CaCO3

 

 

 

Fig. 1. Expt. 1. The pH of peat amended with ground, pulverized, superfine, or
microfine dolomitic carbonate lime (CaCO3 MgCO_,), and analytical grade CaCO3
incorporated at either 2.4, 4.8, or 7.2 kg/m3, respectively, and measured over 21
days. Dotted lines ( """ ) indicate recommended acceptable ranges for the SME
(W amcke and Krauskopf, 1983). Statistical analysis is presented in Table 3.

40

 

 

 

 

 

80 30
l2.4kg/m3 ,
60;
; ~20
40:— l
- /Cl
t // ‘10
”W:
E a, 0:93/ 1 L a A 0 (Dig
< c : 3 we:
orgg, :4.8kg/m 5% CE”
§~w60— “av
SE : 3 $.Em
SE" 20532
..m ' =
‘2401 Us
“-59% : —102%'—5‘
get/>20: \3/ (Drag
3++0:9?/11110ii‘3
o - 3 o
o: :7.2kg/m , a:
60}
- ~20
40:— //B-~~“Cl4
: )3 —10
205g _/_i,/e———-e
E04 1
01 l l l 10

 

0 5 10 15 20
Days from mixing

Fig. 2. Expt 1. Calcium and Mg concentrations of peat amended with ground or
superfine dolomitic carbonate lime (CaCO3 MgCO3) incorporated at either 2.4, 4.8,
or 7.2 kg/m’, respectively, and measured over 21 days. Minimum acceptable
concentrations for Ca is 80 mg/liter and Mg is 30 mg/liter when measured with an
SME (W amcke and Krauskopf, 1983). Statistical analysis is presented in Table 3.

41

 

 

 

 

 

 

 

 

 

 

 

mglliter

 

 

 

 

 

 

 

 

 

..L
N
O
r

mg/liter
mgllite

   

 

 

 

 

lI‘ ‘I‘ LIPII. AI%,I‘0
0369121503691215

 

 

Days from Planting
o GCI A UM I MSUI

 

 

 

 

Fig. 3. Expt. 2. Root-zone pH, EC, NO3-N, PO4-P, Ca, and Mg concentrations of
uncovered subirrigated hybrid impatiens with media containing the blended PNC
fertilizers Greencare I, Uni-mix Plus 11, and MSU I from planting until day 14. The
liming material used was a microfine dolomitic hydrated lime (CaOH2 MgO)
incorporated at 1.5 kg/m’. Dotted lines ( """ ) indicate recommended optimal
concentration(s), the lower dashed line (---) indicates acceptable concentrations for
the SME (W arncke and Krauskopf, 1983). Vertical error bars are mean separation
using LSD.

42

 

EC (dS/m)

 

 

 

 

0 51015202530
Days from Planting

 

Uncovered Covered
0 Top layer 0 Top layer
[1 Root zone I Root zone

Fig. 4. Expt. 2. Comparison of root-zone and top-layer electrical conductivity (EC) for
pots grown without and with an evaporation barrier averaged over media containing
three PNC fertilizers from Experiment 2. Dotted lines ( """ ) indicate recommended
optimal concentration(s), and lower dashed lines (---) indicate acceptable
concentrations for the SME (Warncke and Krauskopf, 1983). Statistical analysis is
presented in Table 4.

43

Root-medium pH Root-medium PO4-P

 

 

 

 

 

 

 

I - 1
40:1, l l 11, l - ,l

0369121503691215

Days from Planting
F0 Hydrated lime (1.5 kg/m’) 0 Carbonate lime (4.5 kg/m’) 0 Carbonate lime (7.5 kg/m’)]

 

 

 

 

Fig. 5. Expt. 2. Root-zone pH and PO4-P concentrations in media containing GC I with
either a microfme dolomitic hydrated lime (CaOH2 MgO) incorporated at 1.5 kg/m3
or a superfine dolomitic carbonate lime (CaCO3 MgCO,) incorporated at 4.5 or 7.5
kg/m’. Dotted lines ( """ ) indicate recommended optimal concentration(s), the lower
dashed line (---) indicates acceptable concentrations for the SME (W amcke and
Krauskopf, 1983). Vertical error bars are mean separation using LSD.

44

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

 

 

 

TopLayer
7 1000
6
5
4
E .
(7) 3
u
2
1
o .
A a II . a L -
RootZon
7 150-----1ooow 500--
EC PO-P Ca . :Mg
6- a ‘ ‘ 500- -
‘120-~ -‘ 800'- - .
5- _ 400:- -
4 5600'- “"L—
E 2 . ,93007 e
200
U 2 E E
1 200 100’
o
O o .
.. . . LzELI. .2 133-211
03691215 03991215 03691215 03691215

Days from Planting
[o GCI v GCII v GCIll El MSUll]

 

Fig. 6. Experiment 3. Root-zone EC, PO4-P, Ca, and Mg concentrations of
subirrigated hybrid impatiens with media containing the blended PNC fertilizers
Greencare I, Greencare II, Greencare III, and MSU II from planting until day 14.
The liming material used was a microfme dolomitic hydrated lime (CaOH2 MgO)
incorporated at 1.5 kg/m3. Dotted lines ( """ ) indicate recommended optimal
concentration(s), the lower dashed line (---) indicates acceptable concentrations for
the SME (Warncke and Krauskopf, 1983). Vertical error bars are mean separation

using LSD.

SECTION III

THE EFFECT OF LIME, IRRIGATION-WATER SOURCE,
AND WATER-SOLUBLE FERTILIZER ON
ROOT-ZONE pH, ELECTRICAL CONDUCTIVITY, AND
MACRONUTRIENT MANAGEMENT OF
CONTAINER ROOT MEDIA WITH IMPATIENS

Journal of the American Society for Horticultural Science
Accepted for publication: 27 Nov. 1996
Published: May 1996 [121(3):442-452]

The Effect of Lime, Irrigation-Water Source, and Water-Soluble Fertilizer on Root-
Zone pH, EC, and Macronutrient Management of Container Root Media with

Impatiens

William R. ArgoI and John A. Biembaum2

Department of Horticulture, Michigan State University, East Lansing, MI 48824-1325

Received for publication 3 July, 1995 . Accepted for publication 27 Nov. 1995 . We

acknowledge the Michigan Agricultural Experiment Station, Bedding Plant Foundation,

Horticulture Research Institute, Fafard, Western Michigan Bedding Plant Association,

and Gloeckner Foundation for supporting this research. Plant material was provided by

Wooden Shoe Greenhouses, Holland, Michigan, and plant tissue analysis was provided

by the Fafard Analytical Services, Athens, Georgia. We also acknowledge the help and

advice of Drs. R. Heins and M. Yelanich with the nonlinear regression analysis. The use

of trade names in this publication does not imply endorsement of the products named or

criticism of similar ones not mentioned.

' Graduate Research Assistant.

2 Associate Professor.

Abbreviations: EC, electrical conductivity; IWS, irrigation water source; PNC,
preplant nutrient charge; RO, reverse osmosis; SME, saturated

media extract; WSF, water-soluble fertilizer.

45

46
Soils, Nutrition, and Fertilizers

The Effect of Lime, Irrigation-Water Source, and Water-Soluble Fertilizer on Root-
Zone pH, EC, and Macronutrient Management of Container Root Media with

Impatiens

Additional index words. calcium, magnesium, peat, phosphorus, tissue analysis,

soilless root media, subirrigation, soluble salts, sulfate

Abstract. Hybrid impatiens (Impatiens Wallerana Hook. F.) were planted in a peat-based
medium containing two dolomitic liming materials (1.8 kg Ca(OH)2-Mg(OH);,/m3 or 8.4
kg CaCO3-MgCO3/m3) and subirrigated for 17 weeks using four irrigation-water sources
(IWS) with varied bicarbonate alkalinity, Ca“, Mg”, and SO4-S content and three water-
soluble fertilizers (WSF) that contained 200-20-200 mg N-P-K/liter but a variable
NH,,:NO3 ratio, Ca”, Mg”, and SO4-S content. The factorial arrangement of the IWS and
WSF resulted in a range of Ca”, Mg”, and SO4-S concentrations varying by a factor of
10. After eight weeks, medium pH ranged from 4.5 to 8.5. The maximum critical
medium pH for PO4-P uptake was 7.4 to 7.7, which probably was due to a change in the
majority of the water-soluble P to the less-available HPOX' form. Lime type did not
affect the long-term increase in medium pH, Ca2+, and Mg2+ concentrations with nutrient
solutions containing low NH4-N and high Ca2+ and Mg”. The carbonate lime buffered
the medium pH and Ca2+ and Mg” concentrations with nutrient solutions containing high
NH4-N and low Ca2+ and Mg” compared to that measured with the hydrated lime. With
both lime types, there was a linear increase in tissue Ca and Mg as the applied
concentrations of the various nutrient solutions increased from 18 to 210 mg Cali/liter
and 7 to 90 mg Mgzi/liter. The relationship was similar for both lime types up to week

eight, afier which tissue Ca and Mg decreased more rapidly with the hydrated lime and

47
low solution Ca2+ and Mg” compared to that of the same carbonate lime treatments. The

minimum critical SO4-S concentration in the applied nutrient solution for plant uptake
was 30 to 40 mg S/liter. Below this concentration, tissue S decreased rapidly; above,

there was little effect on tissue S.

A number of factors, which include lime, the irrigation-water source (IWS),
water-soluble fertilizer (WSF), and plant growth, interact to affect the management of pH
and nutrient concentrations in container root media throughout crop production.
However, not all factors affect medium pH and macronutrient management
simultaneously. A better understanding of how these factors interact is necessary to
improve the recommendations for pH and nutrient management of container-grown crops
over a wide range of conditions.

Lime is added to a soilless root medium to neutralize acidity and increase the pH
to an acceptable level for plant growth. Incorporating sufficient lime into a soilless root
medium to obtain an initial pH range of 5.5 to 6.4 is recommended (Nelson, 1991;
Peterson, 1981; Warncke and Krauskopf, 1983). The amount of liming material required
to obtain an equilibrium pH of 6 in the root medium depends on the incorporation rate
and particle size (Argo and Biernbaum, 1995b; Chapin, 1980; Gibaly and Axley, 1955;
Schollenberger and Salter, 1943; Sheldrake, 1980; Williams et al., 1988b) as well as the
surface area of the liming material (Parfitt and Ellis, 1966). There is some information
about the time required for the lime to reach a stable pH in soilless medium (Argo and
Biernbaum, 1995b; Williams et al., 1988b), the effect of water alkalinity in conjunction
with lime in unplanted pots (Williams et al., 1988a), and the water-soluble Ca2+ and Mg2+
concentrations that can be expected from the incorporation of dolomitic lime into a

soilless medium (Argo and Biernbaum, 1995b; Warncke and Krauskopf, 1983).

48
However, it has been suggested that not all the incorporated liming material may have

reacted upon reaching equilibrium (Argo and Biernbaum, 1995b). The significance of
residual or unreacted lime on the long-term pH or water-soluble Ca2+ and Mg2+ buffering
capacity in soilless media containing plants has not been quantified.

Several studies have been conducted to quantify the nutrient content of different
sources of irrigation water in the United States. Ludwig and Peterson (1984) found that
throughout the US, titratable alkalinity ranged from 2 to 575 mg CaCO3/liter (average =
147 mg/liter); electrical conductivity (EC), from 0 to 6.5 dS/m (average = 0.5 dS/m);
Ca2+, from 0 to 440 mg/liter (average = 60 mg/liter); Mg“, from 0 to 300 mg/liter
(average =20 mg/liter); and Na+, from 0 to 1150 mg/liter (average = 35 mg/liter), based
on 687 water samples from the greenhouse industry. Reddy et a1. (1994) found that only
11% of the IWSs tested contained sufficient concentrations of SO4-S (30 mg/liter)
recommended for plant growth in container culture.

Different IWS require different types of management (Bunt, 1988; Nelson, 1991;
Vetanovetz and Hulme, 1991). Irrigation water containing large amounts of bicarbonate
alkalinity (>250 mg CaCO3/liter) commonly are treated by adding strong mineral acid
(HNO3, H2804, or H3PO4). Researchers recommend adding sufficient acid to reduce the
alkalinity to 100 to 120 mg CaCO3/liter or reduce the solution pH to 6.0 to 6.5 (Bunt,
1988; Nelson, 1991; Spurway and Wildon, 1938). Alternative sources such as rainwater
or reverse osmosis (RO) purified water are gaining popularity because of their low
alkalinity (Biernbaum, 1992). However, rainwater and R0 water contain minimal
nutrients.

The type of WSF applied to a root medium affects pH and nutrient concentrations
two ways: directly, by nutrients applied to the root medium, and indirectly, by
acidification of the rhizosphere pH. Fertilization with NO3'-N causes the medium pH to

increase because of OH' or HCO,‘ secretion associated with balancing ion uptake. In

49
comparison, fertilization with NHf—N causes the medium pH to decrease because of H+

secretion during root uptake and nitrification of the NHf-N to the NO3’-N form, which
also releases H+ (Barker and Mills, 1980; Bunt, 1988; Hawkes et al., 1985; Marschner,
1986; Nelson, 1991; Vetanovetz and Hulme, 1991).

Many commercially available WSF contain a high percentage of NHf-N and P04-
P but little Mg2+ and no Ca2+ [examplesz Peter's 21-7-7 Acid Special, 100% NHf-N,
0.05% Mg“, 0% Ca”; Peter's 20—20-20 General Purpose, 72% NHf-N, 0.05% Mg”, 0%
Ca“; Peter's 20-10-20 Peatlite Special, 40% NHf-N, 0.05% Mg“, 0% Ca2+ (Peter's
Fertilizer [Scotts], Marysville, Ohio)]. Because of the high NHf-N content, the reaction
produced by these WSF are acidic [21-7-7 = 780 kg acidity/ 1000 kg, 20—20-20 = 300 kg
acidity/ 1000 kg, 20-10-20 = 210 kg acidity/ 1000 kg (Peter's Fertilizer)]. In comparison,
WSF that produce neutral or basic reactions in the root medium are typically low in
NHf—N and PO4-P but high in Ca2+ and NO,’-N (examples: Peter's 19-0-16 Western
Greenhouse Formula, 24% NHf-N, 6.5% Ca“, 15 kg acidity/ 1000 kg; Excel 15-5-15,
28% NHf-N, 12% Ca”, 68 kg basicity/ 1000 kg; Peter's 15-0-15 Dark Weather Special,
13% NHf-N, 14% Ca“, 210 kg basicity/ 1000 kg).

Emphasis needs to be placed on designing a WSF program for container plant
production based on a given medium and IWS (Biernbaum, 1992; Vetanovetz and
Knauss, 1988). However, these proposed strategies have not been tested under controlled
conditions. The objectives of this experiment were to determine how lime, IWS, and
WSF interact to affect the management of root-medium pH and medium and shoot-tissue
macronutrient concentrations over time.

Materials and Methods

The experiment included 24 treatments composed of two types of lime, four types

of IWS, and three types of WSF combined in a 2 x 4 x 3 factorial arrangement. At each

sampling date, four pots from each treatment (two pots from each of two greenhouse

50
sections) were sampled. Replication was made between greenhouse sections, while the

two pots taken from the same greenhouse section were treated as subsamples for the
statistical analysis.

Soil test data were analyzed using SAS's analysis of varience (ANOVA)
procedures (SAS Institute, Cary, NC) as a 2 x 4 x 3 split-plot factorial with lime as the
main plot and the other factors as subplots at each sampling date. Medium EC and
nutrient concentration data were transformed to log(observed + 1) for the ANOVA
because of differences in sample variance between treatments. Time was not included in
the AN OVA because sample variance changed over time.

Because of the factorial arrangement of the experiment, a range of Ca“, Mg”,
and SO4-S concentrations in the nutrient solutions, as well as a range of medium pH
values were obtained with the different treatments. Relationships were developed
between the concentration of Ca2+ and Mg2+ in the applied nutrient solutions and tissue Ca
and Mg using SAS's linear regression procedure (REG). Relationships also were
developed between the concentration of SO4-S in the nutrient solutions and the tissue S
and root-medium pH and tissue P using the intersecting straight line model proposed by
Anderson and Nelson (1975) with multiphase functions proposed by Fisher (1995). The

functions used were

. . _ .12;1_I
Xrntersectron -— S] _ SZ [1]
If: X < Xintersection, then: Y = SlX +11 [2]
If: X > Xintersection, then: Y = SZX +12 [3]

where the X value is either SO4-S concentration in mg/liter or root medium pH, Y is

tissue S or P in percent of total dry mass, X is the intersection point of the two

intersection

lines where the Y values are equal and was calculated using Eq. [1], and S and I are the

slope and y-intercept of Eqs. [2] and [3], respectively. Initial estimates for the parameters

51
were obtained from a graph of the observed data. Estimates for 8,, 1,, $2, and 12, based on

either the applied SO4-S or root-medium pH, were obtained using SAS's nonlinear
regression procedure (N LIN).

Lime. The two liming materials varied in reactivity and incorporation rate. A
microfine dolomitic hydrated lime (97% Ca(OH)2 MgO, National Lime and Stone,
Findlay, Ohio) in which 92% of the material passed through a 45-um (#325) screen was
incorporated at 1.5 kg/m3. At this incorporation rate, the hydrated lime added 0.5 kg
Ca”, 0.3 kg Mg”, and the equivalent of 2.6 kg CaCO3/m3 to the root medium. A
superfine dolomitic carbonate lime (99.5% CaCO3 MgC03, National Lime and Stone,
Findlay, Ohio) in which 65% of the material passed through a 75-um (#200) screen was
incorporated at 8.4 kg/m3. At this incorporation rate, the carbonate lime added 1.8 kg
Ca”, 1.1 kg Mg”, and the equivalent of 9.1 kg CaCO,/m3 to the root medium.

The root medium used was (by volume) 70% Canadian Sphagnum peat (Fisons
professional black bale peat, Sun Gro Horticulture, Bellevue, Wash.) with long fibers and
little dust (Von Post scale 1-2; Puustjarvi and Robertson, 1975), and 30% perlite. A
preplant nutrient charge (PNC) consisting of 0.6 kg each of Ca(NO3)2, KNO3, triple
superphosphate (0 N-l9.8 P-0 K), and gypsum; 0.3 kg MgSO4; 0.07 kg fritted trace
elements (FTE 555, Scotts, Marysville, Ohio); and 0.2 liter of a wetting agent (Aquagro
2000 "L," Aquatrols, Pennsaulken, NJ.) per m3 of medium, in addition to the lime, were
added at mixing. Sufficient RO water was added at mixing to bring the moisture content
of the medium to 40% to 50% of container capacity, and the medium was allowed to
equilibrate for three days before planting. At planting, the hydrated lime treatments had a
pH of 6.1, an EC of 2.3 dS/m, and 220 NO3-'N, 14 NHf-N, 40 PO4-P, 200 K, 250 Ca”,
185 Mg”, and 110 SO4-S (mg/liter); while the carbonate lime treatments had a pH of 5.5,
an EC of 2.6 dS/m, and 220 NO,'-N, 13 NHf-N, 53 PO4-P, 215 K”, 230 Ca”, 160 Mg”,

52
and 95 SO4-S (mg/liter), based on the saturated-medium extract (SME) method

(Warncke and Krauskopf, 1983).

Irrigation-water source (IWS). The four IWS varied in EC, Ca”, Mg”, Nai, SO,-
S concentration, and alkalinity content. The high-alkalinity water source (well water) had
a pH of 7.8, an EC of 0.6 dS/m; 105 Ca”, 35 Mg”, 12 Na", 23 SO4-S (mg/liter); and a
titratable alkalinity to pH 4.5 (Chau, 1984) of 320 mg CaC03/liter. The low-alkalinity
water source was RO purified well water, which had a pH of 5.5, an EC of 0.1 dS/m; 20
Ca”, 7 Mg”, 23 Na+, 1 SO4-S (mg/liter); and a titratable alkalinity to pH 4.5 of <20 mg
CaCO,/liter. The third type of water (acidified water) was produced by adding H2S04
(93%) to the well water and had a pH of 5.8, an EC of 0.7 dS/m; concentrations of Ca”,
Mg”, and Na+ similar to that of the well water; 91 mg SO4-S/m3; and a titratable
alkalinity to pH 4.5 of 120 mg CaCO3/liter. The forth irrigation water (well + RO water)
was produced by blending well and R0 water (1:1.5 by volume) and had a pH of 6.8, an
EC of 0.3 dS/m; 56 Ca”, 12 Mg”, 21 Na+, and 9 SO4-S (mg/liter); and a titratable
alkalinity to pH 4.5 of 130 mg CaCO,/liter.

Water-soluble fertilizer (WSF). Fertilizer concentrations were maintained at 150-
15-150 mg N-P-K/liter for the first two weeks and increased to 200-20-200 mg N-P-
K/liter for the remainder of the experiment. The three WSF varied in NHf-N, Ca”,
Mg”, and SO4-S concentrations. At 200 mg N/liter, WSF 1 contained 50% NHf-N with
0 Ca”, 0 Mg”, and 42 804-8 (mg/liter); WSF 2 contained 25% NHf-N with 50 Ca”, 25
Mg”, and 35 SO4-S (mg/liter); and WSF 3 contained 3% NHf-N with 100 Ca”, 50 Mg”,
and 3 SO4-S (mg/liter). Micronutrients (Fe, Mn, Zn, Cu, B, and Mo) were added to all
WSF treatments with a commercially available chelated material (Compound 111 [1.50
Fe-0.12 Mn-0.08 Zn-0.ll Cu- 0.23 B-0.11 Mo], Scotts, Marysville, Ohio) at a constant
50 mg/liter.

53
The type of reaction produced by the WSF was calculated, with values for the

reaction produced by the individual salts obtained from Hawkes et al. (1985) and Young
and Johnson (1982) multiplied by the percentage that each salt contributed to the total
WSF weight. The value obtained for each WSF was used as an estimate of the type
(either acidic or basic) and strength (in kg/ 1000 kg of fertilizer) of reaction produced.
Based on these calculations, WSF l (acidic WSF) had an acidity of 199 kg/ 1000 kg, WSF
2 (neutral WSF) had a basicity of 8 kg/ 1000 kg, and WSF 3 (basic WSF) had a basicity of
175 kg/ 1000 kg.

Plant culture. The experiment was conducted starting 15 Feb. 1994 at Michigan
State University, East Lansing, in two well-ventilated glass greenhouse sections with
constant air circulation and cement floors. One hybrid impatiens plug (Impatiens
wallerana Hook. F. cv. Super Elfin Violet) from a size 512 plug tray was planted into a
9-cm-tall by 12.5-cm-wide (0.75-liter) plastic pot containing medium with one of the two
lime types. Twenty-five pots containing medium with each lime type were placed on one
of 12 flood subirrigation bench sections in each of the two greenhouses. Both lime types
were placed on the same bench section.

Plants on each bench section were irrigated as needed. The time to irrigate was
determined gravimetrically when the average mass of six randomly selected pots
containing plants and medium (three from each lime treatment) reached a target weight
based on a loss of 40% to 50% of the available water. The same six pots were checked
daily for the target weight, and when it was reached, nutrient solutions were applied.
During an irrigation, benches were filled from a 70-liter reservoir for 2 min to a
maximum depth of 2.5 cm and drained in 6 min to the same reservoir. The difference
between the mass of the pots before and after the irrigation was the amount of water
absorbed by the medium. The amount of nutrients applied per pot was calculated as the

sum of the absorbed nutrient solution multiplied by the concentration applied for each

54

irrigation. The nutrient solutions in the 70-liter reservoirs were emptied and prepared
fresh weekly.

Root media were sampled initially and collected from four pots (two per treatment
fiom each bench section) at 1, 4, 8, 12, and 17 weeks after planting. All the medium was
removed from each pot and separated horizontally into two samples, one containing the
top 2.5 cm (top layer), and the other containing the remaining medium from the pot (root
zone). Nutrients contained in each media sample were tested using the SME method with
R0 purified water as the extractant (Warncke, 1986). Only EC was measured in the top
layer sample, while pH, EC, NO,‘-N and NHf-N, PO4-P, K+, Ca”, Mg”, and 804-8 were
measured in the root zone sample. Medium pH was determined by inserting the pH
electrode directly into the saturated medium before extraction, and EC and
macronutrients were measured in the extracted solution. Medium EC was determined
with a platinum electrode at a standard 25C. Nitrate N (Diamond, 1986a), NHf-N
(Diamond, 1986b), PO4-P (Bloxham, 1990), Mg” (magnesium blue, Technicon
Instruments, Tarrytown, NY), and 804-8 (McKnight, 1991) were determined
colorimetrically. Medium K+ and Ca” were determined by the Michigan State University
soil and nutrient testing laboratory using emission spectroscopy.

Shoot fresh and dry weight and tissue nutrient analysis were determined for four
plants per treatment at 4, 8, 12, and 17 weeks after planting. At week four, the entire
plant was used in the sample. For the remaining plants, all shoots were pinched back,
leaving one intemode per stem and four to six stems per plant. At all subsequent
sampling dates, only growth after the previous pinch was sampled, and the remaining
plants were cut back to the week four pinch level. Shoot N and S were determined by
column chromatography, and shoot P, K, Ca, and Mg were determined by plasma

emission spectroscopy (Fafard Analytical Laboratory, Athens, Georgia).

55
Results and Discussion

Plant growth. In general, the experimental treatments affected shoot growth of
impatiens minimally (Fig. 1). The average dry mass of the stem below the pinched
material was 1.9 g at the end of the experiment (data not shown). Averaged over all
treatments, a total of 17.5 g of shoot dry mass was produced over the 17 weeks of the
experiment.

In many experiments, plant shoot tissue is sampled sequentially over time or at
the end of the experiment (Adams et al.; 1978; Argo and Biernbaum, 1994; Argo and
Biernbaum, 1995a, Yelanich, 1995; Yelanich and Biernbaum, 1993). Determining
changes in nutrient availability over time is difficult because the nutrient content of the
shoot tissue represent the sum of the conditions under which the growth occurred.
Cutting the plants back at four week intervals lefi minimal shoot tissue that could be used
as a nutrient reservoir for mobile macronutrients (N, P, K, Mg) while sampling only the
new growth tested the ability of the plants to take up mobile and immobile
macronutrients (Ca, S) over the four week period. Therefore, there should have been a
better correlation between the availability of nutrients in the root medium and tissue
nutrient concentrations over the four week period than if the plants were allowed to grow
from planting until the sampling date, as typically has been done.

Water and fertilizer applications. The volume of nutrient solutions applied
ranged from 7.2 to 8.9 liters/pot over the 17 weeks of the experiment (Table 1). The
volume of water applied to the impatiens in this experiment was similar to that required
by other species for their normal production schedule (Argo and Biernbaum, 1994; Argo
and Biernbaum, 1995b; Yelanich, 1995; Yelanich and Biernbaum, 1993).

Because the N-P-K concentrations in the WSF were constant, the amount applied
was similar and ranged from 1.5 to 1.8 g N, 0.15 to 0.20 g PO4-P, and 1.5 to 1.8 g K” per
pot (data not shown). In addition, 0.1 g N, 0.1 g PO4-P, and 0.2 g K+ per pot were

56
incorporated initially with the PNC fertilizers. In comparison, the concentrations of Ca”,

Mg”, and SO4-S in the nutrient solutions varied by a factor of ~10. The amount applied
ranged from 0.2 to 1.6 g Ca”, 0.1 to 0.7 g Mg”, and 0.1 to 1.2 g SO4-S per pot (Table 1).
In addition to the nutrient solutions applied, hydrated lime treatments received 0.7 g Ca”,
0.3 g Mg”, and 0.1 g SO4-S per pot, and the carbonate lime treatments received 1.5 g
Ca”, 0.8 g Mg”, and 0.1 g SO4-S per pot with the initial incorporation of the lime and
PNC fertilizers.

Based on the mass of shoot tissue produced, sufficient nutrients were applied to
all treatments to maintain tissue nutrient concentrations at levels recommended by
Fortney and Wolf (1981) for floriculture crops. For example, a constant 2% tissue Ca
content would have required z 0.35 g Ca”/pot from the root media. The minimum
amount of Ca” applied to a single treatment throughout the experiment was 0.9 g
Ca”/pot.

Root-zone pH. By week four, root-medium pH was similar for both lime
treatments (Fig. 2, Table 2). Because of the highly reactive nature and small particle size
of the hydrated lime, most of the material probably had reacted by week four. Assuming
that similar equivalents of lime were required to obtain the same root-medium pH, z6 kg
of the carbonate lime per m3 of medium, or 4.5 g/pot, remained unreacted at the week
four analysis.

After eight weeks, the root-zone pH ranged from 4.5 to 8.5 within the various
treatments (Fig. 2, Table 2). Over the remaining nine weeks of the experiment, root-zone
pH was unaffected by lime type with Ca” concentrations in the nutrient solution >150
mg/liter and root-medium pH >6.4 (Fig. 2, Table 2). In comparison, the root-medium pH
was higher in the carbonate lime treatments than in the hydrated lime treatments with
Ca” concentrations in the nutrient solution <150 mg/liter and root-medium pH <6.0. The

largest difference was measured in the RO water/neutral WSF treatment in which the

57
carbonate lime treatment maintained a root-medium pH of 6.1, 5.9, and 5.8; the hydrated

lime treatment, 5.1, 4.6, and 4.6 at weeks 8, 12, and 17, respectively. These values
indicate that there were considerable amounts of unreacted carbonate lime in the root
medium at week four, which greatly increased the pH buffering capacity of the root
medium under acidifying conditions.

The effect of the WSF reaction on root-medium pH also depended on the
alkalinity of the IWS. In general, IWS with similar alkalinity levels had a similar root-
medium pH throughout the experiment (Fig. 2, Table 2). The root-medium pH range
obtained with well water was larger than that with R0 water. Thus, if general guidelines
for using WSF to manage pH in container media are to be based on the reaction
produced, the bicarbonate alkalinity concentration of the IWS and the presence or
absence of residual lime must be taken into account. If low quantities of residual lime are
present and the alkalinity is at or below the 120 mg CaCO3/liter recommended by Bunt
(1988), then the amount of NH4-N in the WSF must be decreased below 25% to prevent
medium pH from falling below recommended acceptable levels.

EC. With all treatments, there was a rapid decrease in root-zone EC as well as the
concentration of all macronutrients tested (N, P, K, Ca, Mg, S) between planting (average
EC = 2.5 dS/m) and week one (average EC = 0.9 dS/m) (Fig. 2), with a corresponding
increase in the nutrient concentration measured in the top 2.5 cm of root medium within
the pot (average EC = 4.7 dS/m) (data not shown). These data indicate that the initial
nutrient concentration represents a highly soluble fraction and is not representative of the
long-term nutrient buffering capacity of the root medium, conclusions similar to those of
Argo and Biembaum (1995b) with blended PNC materials in short-term (14-day)
experiments.

The stratification of fertilizer salts may be caused by evaporation from the root-

medium surface (Argo and Biernbaum, 1994; Argo and Biernbaum, 1995a, 1995b) or a

58
water front moving into the root medium with each irrigation (Yelanich, 1995). After

week four, the root-zone EC increased for the remainder of the experiment (Fig. 2, Table
2). By the end of the experiment, the EC of the top 2.5 cm of root medium ranged from
30 to 40 dS/m compared to 1 to 2.5 dS/m for the remaining root medium within the same
pot as measured with the SME.

EC is a measure of the total salt concentration in the root medium (Warncke and
Krauskopf, 1983). The effect of the treatments on root-zone EC was based on a
combination of the IWS and WSF EC. For example, with the acidified water, root-zone
EC ranged from 1.8 to 2.4 dS/m with the different types of WSF. The root-zone EC of
the RO water treatments averaged 0.5 dS/m lower than that of the acidified water
treatments from week eight until the end of the experiment. When comparing WSF
across IWS, the basic fertilizer/acidified water treatment had a root-zone BC 1.3 dS/m
higher than the acidic fertilizer/R0 water by the end of the experiment. It is important to
note that the concentration of N and K in the applied nutrient solutions were similar for
all treatments and the range of treatments affected root-medium K minimally, and tissue
N and K concentrations were in the acceptable plant-grth range recommended by
Fortney and Wolf (1981) (data not shown). In order to fine tune general guidelines for N
and K nutrition in container media based on EC, the EC of the nutrient solution must be
considered.

Phosphorus. The constant application of 20 mg PO4-P/liter resulted in water-
soluble PO4-P medium concentrations ranging from 3 to 25 mg PO4-P/1iter by the end of
the experiment (Fig. 2). In general, the higher the root-medium pH, the lower the root-
medium PO4-P/m3.

In mineral soils fertilized with P, calcium phosphates (dicalcium phosphate and
dicalcium phosphate dihydrate) initially control PO4-P solubility at high pH (>70) and Al
and Fe phosphates control PO4-P solubility at low pH (Lindsay and Moreno, 1960). In

59
acidic organic soils and soilless root media, which tend to contain naturally low amounts

of Al and Fe, P does not precipitate at low pH but does at high pH (Lucas and Davis,
1961; Peterson, 1981; Yeager and Barrett, 1985). Thus, the reduction in the
concentration of water-soluble PO,-P at the higher pH range probably was due, at least
initially, to precipitation of P as dicalcium phosphate or dicalcium phosphate dihydrate.

Lucas and Davis (1961) and Peterson (1981) concluded that the optimal pH for
PO4-P nutrition was 5.5 in media without soil, because above this pH, water-soluble P04-
P concentrations began to decrease. In comparison, Adams et a1. (1978) found that the P
content of lettuce leaves was unaffected by medium pH up to 6.5, even though the
concentration of water-soluble PO4-P measured in the medium was 38% of that measured
at pH 5.5. In this experiment, when root-medium pH was plotted against tissue P
concentration, a maximum critical root-medium pH for PO4-P nutrition was 7.5, 7.7, and
7.4 at weeks 8, 12, and 17, respectively (Fig. 3, Table 3). Below this root-medium pH,
tissue P increased at 0.06% to 0.08% of the total dry mass per 1 pH unit decrease, and
above the critical pH, tissue P decreased at 0.38% to 0.65% of the total dry mass per 1 pH
unit increase (Table 3).

The form of water-soluble PO4-P is important for uptake into the roots and
depends on the root-medium pH. In the root-medium pH range of this experiment (4.5 to
8.5), the two forms present are HZPO; and HPO,” with an equilibrium constant of 7.2.
The HZPO,’ form of water-soluble P is 10 times more available to the plant than the
HPO,” form (Bunt, 1988). At a medium pH >7.2, a majority of the water-soluble P is in
the less-available HPO,” form that resulted in the larger reduction in tissue P than at a
medium pH <7.2, at which a majority of the measured P is in the more-available HZPO;
form. Thus, while the concentration of water-soluble PO4-P in the root medium
decreased with increasing pH, the effect on tissue P was minimal until the form of the

water-soluble PO4-P changed to a less-available form.

60

Calcium. After week one, root-medium Ca” concentrations increased for the
remainder of the experiment, but the increase depended on all three factors tested (Fig. 2,
Table 2). In general, the higher the concentration of Ca” in the nutrient solution, the
higher the water-soluble Ca” concentration in the root medium over the remaining 16
weeks of the experiment. The presence of the carbonate lime also increased water-
soluble Ca” compared to that of the hydrated lime treatments, but the average difference
was small (S 20 mg Ca”/liter) and probably was due to the reaction of the acidic or
neutral WSF with residual carbonate lime in the medium.

There was a poor relationship between water-soluble Ca” concentrations in the
root medium and tissue Ca (data not shown). The root-medium Ca” concentrations
measured at weeks 4, 8, 12, and 17 are the maximum concentrations from the previous
four-week period and therefore do not represent the "average" conditions from which
plant growth and Ca uptake occurred. In comparison, the range of Ca” concentrations in
the various nutrient solutions produced from the factorial combinations of IWS and WSF
remained constant over time, and there was a relationship between the applied Ca”
concentration in the nutrient solution and tissue Ca.

With both lime types, there was a linear increase in tissue Ca as the applied
concentrations increased from 20 to 210 mg Ca”/liter with the IWS and WSF
combinations (Fig. 4, Table 4). The intercept value reflects the Ca” buffering capacity of
the medium if no Ca” were applied in the fertilizer solution. The relationship was similar
for both lime types up to week eight (0.2% increase in tissue Ca per 40 mg/liter increase
in applied Ca” concentration, with a minimum tissue concentration of 1.0% to 1.1%),
after which tissue Ca decreased faster with the hydrated lime and low-solution Ca”
compared to that of the carbonate lime treatments. The reduction in the intercept of the
hydrated lime treatments by weeks 12 and 17 indicates a reduction in the Ca” buffering

capacity of the medium compared to that of the carbonate lime treatments. Using Eq. [1],

61
similar tissue Ca concentrations could be obtained, independent of the lime type, with the

addition of >180 mg Ca”/liter in the nutrient solution throughout the experiment. In
addition, these results indicate that the ionic composition and N form of the WSF had
little effect on Ca uptake. Instead, the main factor controlling Ca uptake above the
minimum buffering capacity of the medium was bulk nutrient solution Ca” concentration
as influenced by the IWS and WSF.

One possibility for the larger reduction in tissue Ca with the hydrated lime
treatments compared to that of the carbonate lime treatments was that Ca” availability
was reduced at low pH, as indicated by Peterson (1981). Plants grown in media
containing the hydrated lime and irrigated with R0 water containing either acidic or
neutral WSF had a similar root-medium pH throughout the experiment (Fig. 2), but the
total applied Ca” concentration was higher with the neutral WSF (70 mg Ca”/liter) than
the acidic WSF (20 mg Ca”/liter). The tissue Ca concentration was also higher with the
RO-neutral WSF treatment at each of the four sampling date (1.6%, 1.7%, 1.7%, and
1.3%, respectively) than with the RO-acidic WSF (1.3%, 1.1%, 0.8%, and 0.5 %,
respectively) (Fig. 4). Thus, low pH did not, in itself, reduce Ca” uptake but did reflect a
lack of residual lime in the medium. The difference in tissue Ca concentrations between
the hydrated (1.3% Ca) and carbonate (1.7% Ca) lime treatments in plants receiving RO
water/neutral fertilizer at the week 17 sampling date reflects the additional buffering
capacity of the residual carbonate lime.

Magnesium. As with Ca”, root-medium Mg” concentrations increased from
week one to the end of the experiment, and the increase depended on all three factors
tested (Fig. 2, Table 2). In general, the higher the concentration of Mg” in the nutrient
solution, the higher the water-soluble Mg” concentration in the root medium over the
remaining 16 weeks of the experiment. The presence of the carbonate lime increased

water-soluble Mg” compared to that of the hydrated lime treatments, but the difference

62
was small (3 15 mg Mg”/liter), and probably was due to the reaction of the acidic

fertilizer with the carbonate lime.

With both lime types, there was a linear increase in tissue Mg as the applied
concentrations increased from 5 to 80 mg Mg”/liter with the various nutrient solutions
(Fig. 5, Table 5). The intercept value reflects the Mg” buffering capacity of the medium
if no Mg” were applied in the fertilizer solution. The relationship was similar for both
lime types up to week eight, after which tissue Mg decreased with the hydrated lime and
low-solution Mg”, while with the carbonate lime treatments, there was little decrease in
tissue Mg with decreasing concentrations of applied Mg” (0.05% increase in tissue Mg
per 25 mg/liter increase in applied Mg” concentration). From Eq. [1], similar tissue Mg
concentrations were obtained, independent of the lime type, with the addition of >60 mg
Mg”/1iter in the nutrient solution for the duration of the experiment. These results
indicate that the ionic composition and N form of the WSF had minimal effect on Mg
uptake. The main factor controlling Mg uptake above the minimum buffering capacity of
the medium was bulk nutrient solution Mg” concentration, as influenced by the IWS and
WSF.

Sulfate. Irrigation-water source and WSF were the main factors affecting root-
medium SO4-S concentrations (Fig. 2, Table 2). In general, the higher the concentration
in the applied nutrient solution, the higher the concentration of SO4-S in the root medium
at the end of the experiment. When low concentrations of 804-8 were applied (RO
water/basic fertilizer), low concentrations were measured in the root medium, indicating
that gypsum and MgSO4 initially incorporated with the PNC had minimal persistence in
the root zone. However, with the lowest applied SO4-S concentration (3 mg SO4-S/liter),
root-zone SO4-S concentrations were maintained at 15 mg SO4-S/liter and may represent
the base buffering capacity of the root medium, residual gypsum, or movement of 804-8

back into the root zone from high concentration at the root-medium surface.

63
There was a minimal increase in tissue S with increasing concentration of applied

SO4-S above 30 to 40 mg S/liter (Fig. 6, Table 6). Above this concentration, tissue S
increased at 0.0% to 0.05% of dry mass per 30 mglliter increase in the applied SO4-S
concentration. Below this minimum critical concentration, tissue S decreased at 0.2% to
0.5% of dry mass per 30 mg/liter decrease in the applied SO4-S concentration. This
minimum critical concentration of 30 to 40 mg S/liter corresponds to the 30 mg S/liter
recommended by Reddy et al. (1994) for container plant production. In addition, the
larger reduction in tissue S at the week four analysis (below 40 mg S/liter in the applied
solution) adds further evidence that a large percentage of the gypsum or MgSO4 did not
persist in the root zone, as suggested in this experiment and by Argo and Biembaum
(1995b) and root-medium Ca” and tissue concentrations. Reddy et al. (1994) found that
11% of the IWS tested, based on a survey of water samples, contained >30 mg S/liter.
Since many blended WSF do not contain SO,-S (Peter's Fertilizers, 1981), additional
SO4-S may need to be added as a water-soluble source, as suggested by Reddy and
Madore (1995).

Root-medium SO4-S concentrations up to 150 mg S/liter and applied
concentration up to 130 mg S/liter did not cause a significant decrease in tissue Ca
concentrations (plant tissue Ca average with acidified water = 1.9%, 2.0%, 2.4%, and
2.1%; and with well water = 1.8%, 1.9%, 2.3%, and 2.0% at weeks 4, 8, 12, and 17,
respectively). Although Ca” and SO4-S will form soluble ion complexes in solution
(Lindsay, 1979), which may reduce plant availability, under the conditions of the
experiment, enough of the water-soluble Ca” remained in the root medium in the free ion
form to not inhibit plant uptake.

Root-medium buflering capacity. The pH and nutrient buffering capacity of peat
often are associated with the cation exchange capacity (CEC) that is due to the pH-

dependent exchange of cations with H“ ions from organic acid functional groups on the

64
peat particles (Helling et al., 1964). For example, at a pH of 3.7, 4.5, 5.5, and 7.8, acid

Sphagnum peat is 100%, 50%, 30%, and 0% Hi saturated, respectively (Lucas et al.,
1975; Puustjarvi and Robertson, 1975). Thus, the actual buffering capacity over the pH
range in this experiment probably represents a fraction of the total CEC.

This experiment demonstrated that a large difference in pH and nutrient buffering
capacity could be obtained with the same root medium by using two liming materials
with different reaction rates and amounts of unreacted material remaining in the medium
at equilibrium. Perhaps differences in the pH and nutrient buffering capacity observed in
commercial media may be attributed to differences in the type and amount of liming
material used rather than CEC (C. Bethke, Michigan Peat, Houston, Texas, personal
communications).

Macronutrient management. The primary macronutrients (N, P, K) typically are
contained in WSF. Nitrogen and K can be managed based on the EC of the nutrient
solution. If PO4-P is present in the WSF, it also can be managed acceptably via EC if the
root-medium pH is <7.3 to 7.5.

The secondary macronutrients (Ca, Mg, and S) frequently are ignored because the
carriers (lime, gypsum, and MgSO4) are incorporated in relatively large amounts with the
PNC fertilizers and may buffer the root media for a long period (Bunt, 1988; Nelson,
1991). Gypsum and MgSO4 do not persist in the root zone of subirrigated pots and
probably can be removed by top-watering methods with leaching or mist propagation.
Dolomitic carbonate lime buffered the root medimn for Ca” and Mg”, but long-term
reliance on residual lime may be risky, because the amount of material present or its
persistence in the medium cannot be determined with the SME analysis.

An alternative method for managing secondary macronutrients may be to ignore
the material incorporated with the PNC and lime in the medium and apply nutrient-

solution Ca”, Mg”, and SO4-S based on the sum of those ions from both the IWS and

65
WSF, as suggested by Biembaum (1992) and Vetanovetz and Knauss (1988). According

to the results from this experiment, the concentrations of Ca”, Mg”, and 804-8 that
should be applied in the nutrient solution on a constant basis are 160 mg Ca”/liter, 50 mg
Mg”/liter, and 30 mg SO4-S/liter.

There are two main sources of Mg” for WSF, MgSO4 and Mg(NO3)2. If MgSO4
is used for the Mg” source, adequate concentrations of SO,-S also will be applied.
However, there is only one source of highly soluble Ca” typically used in WSF,
Ca(NO3)2. Therefore, the recommendations for Ca” supplied by the nutrient solution also
will have a direct effect on NH4-N content in the WSF and on root-medium pH
management. This type of secondary macronutrient management should result in
acceptable Ca” concentrations for plant uptake, a medium pH maintained at a level much
closer to the recommended 5.8 to 6.4 range (Warncke and Krauskopf, 1983), and the
conservation of any residual liming material.

Calcium and PO4-P can be mixed together in high concentrations, such as in a
fertilizer stock tank, only if the pH <2.0 (R. Vetanovetz, Scotts, Marysville, Ohio,
personal communication), while Ca” and SO4-S cannot be combined in a stock tank
without subsequent precipitation. Multiple injectors may be required for this type of
secondary macronutrient management. Other options for applying Ca” without N may
include investigating the use of CaCl2 if a high percentage of NH4-N and Ca” is desired
in the WSF.

Conclusion. Impatiens are highly tolerant of a wide range of growth conditions.
Because of the similarity in the shoot dry mass accumulation between treatments, the
relationships that were developed between the applied nutrient concentration or medium
pH and the tissue nutrient concentration were not confounded because of differences in
plant growth. These relationships also may be valid for other species used in container-

plant production. However, the minimum critical tissue-nutrient concentrations that

66
causes a reduction in growth may be species dependent (Dole and Wilkins, 1988). If

other species were grown under the same conditions as those found in this experiment, it
is possible that a limitation in growth caused by a nutrient deficiency or toxicity would
have occurred.

In the production of container-grown crops, it is no longer acceptable to manage
the pH and macronutrient concentrations in the root medium and plant tissue with high
WSF concentrations and high leaching rates (Biernbaum, 1992). Irrigation systems that
minimize or eliminate water and fertilizer runoff into the environment currently exist.
Optimizing the pH and nutrient management of low- or nonleaching irrigation systems
requires an understanding of how factors such as lime, IWS, and WSF interact during
production. Additional research is needed to determine if recommendations for pH and
macronutrient management must be refined further to include differences in root media
and or plant species.

Literature Cited

Adams, P., CJ. Graves, and G.W. Winsor. 1978. Some responses of lettuce, grown in beds of
peat, to nitrogen, potassium, magnesium, and molybdenum. J. Hort. Sci. 53:275-281.

Anderson, R.L. and LA. Nelson. 1975. A family of models involving intersecting straight lines
and concomitant experimental designs useful in evaluating response to fertilizer nutrients.
Biometrics 31:303-318.

Argo, W.R. and J.A. Biembaum. 1994. Irrigation requirements, root-medium pH, and nutrient
concentrations of Easter lilies grown in five peat-based media with and without an
evaporation barrier. J. Amer. Soc. I-lort. Sci. 119(6):] 151-1 156.

Argo, W.R. and J .A. Biembaum. 1995. Root-medium nutrient levels and irrigation requirements
of poinsettias grown in five root media. HortScience 30(3):535-538.

Argo, W.R. and J .A. Biembaum. 1996. Availability and persistence of macronutrients from lime

and preplant nutrient charge fertilizers in peat-based root media. J. Amer. Soc. Hort. Sci.

121(3):453-460.

67
Barker, A.V. and HA. Mills. 1980. Ammonium and nitrate nutrition of horticultural crops. Hort.

Rev. 2:395-423.

Biernbaum, J.A. 1992. Root-zone management of greenhouse container-grown crops to control
water and fertilizer use. HortTechnology 2(1):127-132.

Bloxham, A. 1990. Orthophosphate in surface waters. QuikChem method no. 10-115-01-1-0.
Lachat Instruments, Milwaukee, Wis.

Bunt, A.C. 1988. Media and mixes for container-grown plants. Unwin Hyman, London.

Chapin, J.K. 1980. The effect of fineness in limestone on the pH of 50:50 peat-vermiculite mix.
Benchmarks l(7):7.

Chau, A.S.Y. 1984. Water; and salt. p. 617-638. In: S. Williams (ed.). Official methods of
analysis of the association of official analytical chemists. Assoc. of Official Anal. Chemists,
Arlington, Virginia.

Diamond, D. 1986a. Nitrate + nitrite in soil extracts. QuikChem method no. 12-107-04-1-B.
Lachat Instruments, Milwaukee, Wis.

Diamond, D. 1986b. Ammonia in soil extracts. QuikChem method no. 12-107-06-2-A. Lachat
Instruments, Milwaukee, Wis.

Dole, J.M. and HF. Wilkins. 1988. Tissue testing of selected floricultural pot crops. Minnesota
State Flo. Bul. 37(5):l3-15.

Fisher, PR. 1995. Prediction and control of stem elongation and flowering in poinsettia and
Easter lily. PhD Diss., Michigan State Univ., East Lansing.

Fortney, W.R. and T.K. Wolf. 1981. Determining nutritional status: Plant analysis. Pennsylvania
Flower Grower's Bul. 331, 1:5-11.

Gibaly, HE. and J.H. Axley. 1955. A chemical method for the rating of agricultural limestones
used as soil amendments. Soil Sci. Soc. Amer. Proc. 20:301-302.

Hawkes, G.R., D.B. Campbell, A.E. Ludwick, R.M. Millaway, and R.M. Thorup (eds.). 1985.
Fertilizers: A source of plant nutrients, p. 83-110. In: Western fertilizer handbook. 7th ed.

Interstate, Danville, Ill.

68
Helling, C.S., G. Chesters, and RB. Corey. 1964. Contribution of organic matter and clay to soil

cation-exchange capacity as affected by the pH of the saturating solution. Soil Sci. Soc. Amer.
Proc. 28:517-520.

Lindsay, W.L. 1979. Chemical equilibria in soils. Wiley, New York.

Lindsay, W.L. and EC. Moreno. 1960. Phosphate phase equilibria in soils. Soil Sci. Soc. Amer.
Proc. 24:177-182.

Lucas, RE. and J.F. Davis. 1961. Relationships between pH values of organic soils and
availabilities of 12 plant nutrients. Soil Sci. 92:171-182.

Lucas, RE, RE. Rieke, J.C. Shickluna, and A. Cole. 1975. Lime and fertilizer requirements for
peats, p. 51-70. In: D.W. Robinson and J.G.D. Lamb (eds.). Peat in horticulture. Academic
Press, London.

Ludwig, LS. and J.C. Peterson. 1984. An assessment of the chemical properties of water from
floriculture industry firms throughout Ohio and the United States. HortScience 19(3):521.
(Abstr.)

Marschner, H. 1986. Mineral nutrition of higher plants. Academic Press, London.

McKnight, R. 1991. Sulfate: Turbidimetric method with soil extracts. QuikChem method no. 12-
] 16-10-l-C. Lachat Instruments, Milwaukee, Wis.

Nelson, P.V. 1991. Greenhouse operations and management. 4th ed. Prentice Hall, Englewood
Cliffs, NJ.

Parfitt, R.L. and B.G. Ellis. 1966. Studies on Michigan agricultural limestones. Michigan Agr.
Expt. Sta. Quarterly Bul. 49(2):12-23.

Peter's Fertilizers. 1981. Fertilizer sales manual. Scotts, Marysville, Ohio.

Peterson, J.C. 1981. Modify your pH perspective. Florist's Rev. 169(4386):34-35, 92-93.

Puustjarvi, V. and R.A. Robertson. 1975. Physical and chemical properties, p. 23-38. In: D.W.
Robinson and J .G.D. Lamb (eds.). Peat in horticulture. Academic Press, London.

Reddy, SK. and M.A. Madore. 1995. Is there enough sulfur in your water? GrowerTalks
58(8):92.

Reddy, S.K., M.A. Madore, and PA. King. 1994. Survey of sulfur levels in greenhouse irrigation
waters. HortScience 29(5):503. (Abstr.)

69
Schollenberger, CJ. and R.M. Salter. 1943. A chart for evaluating agricultural limestone. J.

Amer. Soc. Agron. 35:955-966.

Sheldrake, R. 1980. Lime source and quantity study on peat-vermiculite-l980. Benchmarks
1(7):6—7.

Spurway, CH. and CE. Wildon. 193 8. Water conditioning for greenhouses. Michigan Agr. Expt.
Sta. Circular Bul. 166:3-10.

Vetanovetz, R. and R. Hulme. 1991. Tested your water alkalinity lately? Greenhouse Manager
9(10):48-50.

Vetanovetz, R.P. and J .F . Knauss. 1988. Water quality. Greenhouse Manager 6(12):64-72.

Warncke, DD. 1986. Analyzing greenhouse growth media by the saturation extraction method.
HortScience 21(2):223-225.

Warncke, D. and D. Krauskopf. 1983. Greenhouse media: Testing and nutrition guidelines.
Michigan State Univ. Ext. Bul. E-1736.

Williams, B.J., J.C. Peterson, and JD. Utzinger. 1988a. Effects of dolomitic lime and alkaline
water in sphagnum peat-based container growing media. HortScience 23(1): 168-169.

Williams, B.J., J.C. Peterson, and JD. Utzinger. 1988b. Liming reactions in sphagnum peat-
based growing media. J. Amer. Soc. Hort. Sci. 1 l3(2):210-214.

Yeager, T.H. and J.E. Barrett. 1985. Phosphorus and sulphur leaching from an incubated
superphosphate-amended container medium. HortScience 20:671-672.

Yelanich, M.V. 1995. Modeling the concentration of nitrogen in the root zone of container-
grown Chrysanthemums. PhD Diss., Michigan State Univ., East Lansing.

Yelanich, M.V. and J.A. Biembaum. 1993. Root-medium nutrient concentration and grth of
poinsettia at three fertilizer concentrations and four leaching fractions. J. Amer. Soc. Hort.
Sci. ll8(6):77l-776.

Young, R. and F]. Johnson. 1982. Fertilizer products, p.45-68. In: The fertilizer handbook. The

Fertilizer Institute, Washington, DC.

70

Table 1. Cumulative water, Ca”, Mg”, and SO4-S applied with the various irrigation-
water source (IWS) and water-soluble fertilizer (WSF) treatments after 17 weeks. The
initial nutrient content of the root medium was not included in the values reported
below but was 0.7 g Ca”, 0.3 g Mg”, and 0.1 g SO4-S per pot with the hydrated lime
treatments and 1.5 g Ca”, 0.8 g Mg”, and 0.1 g SO4-S per pot with the carbonate lime
treatment. Data are the mean of six pots. Statistical analysis indicates a three-way
interaction with > 0.01 significance for all four variables measured.

 

 

 

 

 

 

 

 

 

 

Hydrated lime Carbonate lime
Applied Applied
Well Acidic 7.8 0.8' of 0.6 8.1 09 03’ 0.7
Well Neutral 7.7 1.3 0.5 0.6 7.4 1.2 0.4 0.6
Well Basic 7.2 1.6 0.6 0.3 7.6 1.6 0.7 0.3
Acidified Acidic 8.3 0.8 0.3 1.2 8.0 0.8 0.3 1.2
Acidified Neutral 7.8 1.2 0.5 1.1 7.5 1.1 0.5 1.1
Acidified Basic 7.4 1.5 0.7 0.8 7.5 1.5 0.7 0.8
Well + RO Acidic 8.7 0.5 0.1 0.6 8.1 0.5 0.1 0.5
Well + RO Neutral 8.4 0.9 0.3 0.5 8.1 0.9 0.3 0.5
Well + RO Basic 8.2 1.4 0.5 0.2 8.2 1.4 0.5 0.2
R0 Acidic 8.9 0.2 0.1 0.5 7.8 0.2 0.1 0.5
R0 Neutral 8.4 0.6 0.3 0.5 8.2 0.6 0.3 0.4

R0 Basic 7.8 1.0 0.5 0.1 7.8 1.0 0.5 0.1

 

71

Table 2. Degrees of freedom (d1), F-values (A), levels of significance (B), and mean
square from error a and b (MSE a or b) from the analysis of variance for the
log(observed + 1) transformed root-medium pH, electrical conductivity (EC), PO4-P,
Ca”, Mg”, and SO4-S concentrations at 1, 4, 8, 12, and 17 weeks after planting.

 

 

 

 

 

Week 1 Week 4 Week 8 Week 12 Week 17
(If A B A B A B A B A B
Lime (L) 1 14.7 NS 0.4 NS 162.0 "‘ 972.6 " 32.5 NS
MSE a 1 0.0002 0.0005 0.0001 0.0001 0.0001
IWS ' 3 13.1 *" 33.6 “" 81.1 ”" 40.9 ”“" 61.0 *”
L x IWS 3 2.5 NS 0.5 NS 6.8 *” 2.7 NS 1.8 NS
pH WSF ’ 2 10.5 "* 7.9 "* 155.7 "" 170.6 "" 323.0 *"
L x WSF 2 0.1 NS 1.0 NS 6.3 *" 3.7 " 9.1 *“
IWS x WSF 6 1.4 NS 2.1 NS 4.5 " 4.4 "* 11.6 "*
L x IWS x WSF 6 2.1 NS 0.2 NS 0.9 NS 0.9 NS 3.1 "
MSE b 70 0.0003 0.0003 0.0004 0.0009 0.0005
Lime (L) 1 15.2 NS 0.2 NS 1.6 NS 2.1 NS 9.4 NS
MSE a 1 0.0001 0.0018 0.0027 0.0074 0.0009
IWS 3 24.2 "* 16.4 "" 35.9 "* 28.1 ""' 21.6 "“
L x IWS 3 0.8 NS 0.1 NS 1.4 NS 0.2 NS 2.8 "
EC WSF 2 21.2 "“ 11.3 “* 27.9 *" 26.4 ”"‘ 54.8 "“
L x WSF 2 0.7 NS 0.4 NS 1.4 NS 3.0 NS 11.6 ""
IWS x WSF 6 2.5 * 2.0 NS 1.7 NS 0.3 NS 2.9 "
L x IWS x WSF 6 0.9 NS 1.8 NS 2.1 NS 0.7 NS 1.8 NS
MSE b 70 0.0011 0.0014 0.0010 0.0018 0.0019
Lime (L) 1 1633.6 "‘ 97.9 NS 30.6 NS 0.4 NS 0.0 NS
MSE a 1 0.0004 0.0018 0.0008 0.0188 0.0258
IWS 3 48.1 “* 27.2 ”" 94.8 "* 118.7 "“ 25.2 *"
L x IWS 3 3.9 "”" 1.6 NS 0.6 NS 0.3 NS 0.3 NS
P WSF 2 1.0 NS 29.6 "’" 167.6 “" 303.2 "”” 80.2 ”*
L x WSF 2 4.5 " 0.0 NS 0.7 NS 1.5 NS 0.5 NS
IWS x WSF 6 8.9 *" 9.6 *** 33.1 "* 56.4 ”‘* 12.6 "*
L x IWS x WSF 6 1.0 NS 0.6 NS 1.2 NS 1.3 NS 0.2 NS
MSE b 70 0.0013 0.0041 0.0036 0.0042 0.0138

 

Table 2. (Cont)

72

 

 

 

Lime (L) 1 34.6 NS 0.6 NS 1.7 NS 3.4 NS 958.6 -
MSE a 1 0.0031 0.0027 0.0022 0.0048 0.0001
rws 3 5.2 n 21.9 m 88.1 m 56.9 m 66.7 m
L x rws 3 0.5 NS 1.6 NS 3.2 NS 2.9 NS 2.7 NS
Ca wsr= 2 13.7 m 60.3 m 61.3 m 30.9 m 90.6 m
L x wsr 2 2 2 NS 0.0 NS 2.2 NS 3.5 NS 16.8 m
rws x wsr= 6 0 5 NS 2.7 n 3.9 u 2.0 NS 3.7 n
L x rws x wsr 6 0.4 NS 2.2 NS 3.1 t 0.3 NS 2.2 NS
MSE b 70 0.0138 0.0071 0.0041 0.0081 0.0052
Lime (L) 1 18.6 NS 1.0 NS 13.4 NS 2362.0 * 12.1 NS
MSE a 1 0.0006 0.0100 0.0037 0.0004 0.0030
rws 3 11.7 m 18.5 m 38.1 m 114.2 m 10.9 m
L x rws 3 1.4 NS 5.8 a 5.5 r 17.8 m 3.2 '4
Mg wsr 2 26.0 m 80.5 m 49.2 m 117.9 m 28.5 m
L x wsr= 2 0.4 NS 3.8 NS 0.5 NS 21.8 m 6.4 H
rws x WSF 6 1.5 NS 1.8 NS 2.8 NS 8.9 m 1.9 NS
L x 1ws x wsr 6 1.1 NS 6.1 u 4.2 r 2.9 n 5.9 "
MSE b 70 0.0199 0.0172 0.0249 0.0151 0.0098
Lime (L) 1 8.2 NS 53.2 NS 0.4 NS 5.1 NS 0.0 NS
MSE a 1 0.0023 0.0001 0.0004 0.0023 0.0006
rws 3 133.7 m 404.6 m 366.3 m 177.8 m 332.7 m
L x rws 3 0.4 NS 1.9 NS 0.5 NS 1.3 NS 0.5 NS
8 ws1= 2 56.5 m 504.0 m 199.8 m 112.1 m 294.1 m
L x ws1= 2 3.2 * 0.9 NS 1.0 NS 0.6 NS 3.5 NS
rws x WSF 6 5.1 m 21.1 m 27.0 m 9.8 m 40.0 m
L x rws x wsrs 6 0.5 NS 0.3 NS 1.2 NS 0.7 NS 2.0 *
MSE b 70 0.0054 0.0029 0.0043 0.0080 0.0040

 

' Irrigation—water source.
V Water-soluble fertilizer

NS...O..OOO

Nonsignificant or significant at P 2 0.05, 0.01, or 0.001, respectively.

73

Table 3. Parameters of nonlinear regression analysis from fitting Eqs. [1], [2], and [3] to
percent P in tissue, based on root-medium pH at 8, 12, and 17 weeks after planting. I and
S are the intercept and slope for Eqs. [2] and [3], respectively. The number of
observations per sampling data was 48 at week four and 96 thereafter. Data from the lime
treatments were used in the same analysis and are presented in Fig. 3. The analysis of the
week four data was not included because of nonsignificance.

 

 

 

 

 

Week 8 Week 12 Week 17 units

Estimated parameters

Intercept (1,) 1.31 i 0.102 1.25 d: 0.11 l .212 0.14 % dry mass
Slope (8,) -0.08 :t 0.02 -0.06 i 0.02 -0.07 :t 0.02 % dry mass/1 pH unit
Intercept (12) 3.61 i 0.74 5.13 :t 1.19 4.58 :t 0.88 % dry mass
Slope (S2) 038 :t 0.09 -0.65 :t 0.14 -0.52 i 0.11 % dry mass/1 pH unit
Calculated parameters

X,,,,,,,,,,,,ion 7.5 7.7 7.4 pH

 

ZNinety-five percent confidence intervals were calculated as the parameter standard error " tongs," distribution.

Table 4. Parameters of linear regression analysis for tissue Ca, based on the applied
concentration of Ca” in the nutrient solution. The number of observations per lime
treatment was 24 at week four and 48 thereafier. Data are presented in Fig. 4.

 

 

 

Week 4 Week 8 Week 12 Week 17 units
Hydrated lime
Intercept 1.06 i 0.18' 1.06 i 0.14 1.01 :1: 0.16 0.59 i 0.15 % dry mass
Slope 0.006 t 0.001 0.006 :1: 0.001 0.008 :t 0.001 0.009 :t 0.001 % dry mass/mg L"
Carbonate lime
Intercept 1.08 i 0.25 1.10 3: 0.20 1.48 :t 0.15 1.47 i 0.13 % dry mass
Slope 0.005 i 0.001 0.006 :1: 0.001 0.006 t 0.001 0.004 t 0.001 % dry mass/mg L'l

 

ZNinety-five percent confidence intervals were calculated as the parameter standard error ‘ 10025,“ distribution.

74

Table 5. Parameters of linear regression analysis for tissue Mg, based on the applied
concentration of Mg” in the nutrient solution. The number of observations per lime
treatment was 48 at week four and 96 thereafter. Data are presented in Fig. 5.

 

 

Week 4 Week 8 Week 12 Week 17 units
Hydrated lime
Intercept 0.43 i 0.052 0.42 i 0.05 0.37 i 0.04 0.30 i 0.05 % dry mass
Slope 0.005 :1: 0.001 0.005 :t 0.001 0.006 t 0.001 0.007 a: 0.001 % dry mass/mg L"
seam
Intercept 0.45 :1: 0.06 0.51 3: 0.05 0.61 i 0.06 0.62 i: 0.05 % dry mass
Slope 0.005 i 0.001 0.004 :t 0.001 0.002 :t 0.001 0.002 :1: 0.001 % dry mass/mg L"

 

zNinety-five percent confidence intervals were calculated as the parameter standard error " 10025," distribution.

Table 6. Parameters of nonlinear regression analysis from fitting Eqs. [1], [2], and [3] to
percent S in tissue, based on the concentration of 804-8 in the nutrient solution at 4, 8,
12, and 17 weeks after planting. The number of observations per sampling data was 48 at
week four and 96 thereafter. Data from the lime treatments were used in the same
analysis and are presented in Fig. 6.

 

 

 

Week 4 Week 8 Week 12 Week 17 units
Estimated parameters
Intercept (1,) 0.42 i 0.1 1‘ 0.25 :1: 0.06 0.22 at 0.08 0.28 a: 0.07 % dry mass
Slope (8.) 0.006 :1: 0.002 0.012 d: 0.003 0.015 d: 0.004 0.012 at 0.003 % dry mass/mg L"
Intercept (12) 0.69 :t 0.04 0.58 i 0.05 0.66 i 0.05 0.68 i 0.06 % dry mass

Slope (S2) 0.000 d: 0.001 0.002 i 0.001 0.002 :t 0.001 0.001 i 0.001 % dry mass/mg L"
Calculated parameters
xinterscction 41 32 32 38 mg liter"

 

 

 

ZNinety-five percent confidence intervals were calculated as the parameter standard error " t0_025,n distribution.

75

 

    

New shoot tissue dry weight (g)
0)

 

 

 

O Acidic WSF
1 ' [:1 Neutral ws1= ‘
, A Basic WSF
0 - * 1 '
0 4 8 12 16

Weeks from planting

Fig. 1. Average new shoot dry weight of the three water-soluble fertilizer (WSF)
treatments from impatiens at 4, 8, 12, and 17 weeks after planting. After each harvest,
remaining plants were pruned to the same point. Error bars were calculated as 95%
confidence intervals. Data represent only the new shoot growth from the previous
four-week period.

Porn

 

40

 

 

O’NO

Well
30 >

20 *
10 ).... ................ <

   

......................

]-____

 

 

 

 

Acidified ‘

 

 

 

pH

 

 

 

 

300 _

200

100 '

200

100

(mg/liter)
O

200 (

100

200

100

Fig. 2. Root-medium pH, electrical conductivity (EC), PO4-P, Ca”, Mg”, and 804-8
concentrations in the root zone of plants grown with four inigation-water sources and
three water-soluble fertilizers (WSF) between weeks 1 and 17. Filled symbols are
hydrated lime treatments and hollow symbols are carbonate lime treatments.
dotted lines ("“"") represent the recommended optimal ranges the and dashed lines (----)
represent the lower recommended acceptable range for the saturated media extract
(Warncke and Krauskopf, 1983). Statistical analysis is presented in Table 2. Data are

 

UIQNCDU'IODNCDUIOVGU!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A I g
g o E
‘0 c»
B l E
2 v
1 .
0 -
i 2
1 .
0
125 150 SO,-S
100 - 120 _w611
75 - 90 -
50 . 60 -
25 - 30
0 01
100 120
75 - 90 -
1 50 - - 60 -
E 25 - ‘3 30
E o E 0
g 100 g’ 120
V 75 - V 90 -
50 ~ 60 -
25 - 30
0 o
100 - . 120 -
. 90 .
60 ~
30 — — ——
0 0 - . . -
0 4 8 12 16 o 4 8 12 16
Weeks From Planting
Acidic WSF ( o o ) Neutral WSF( I o ) Basic WSF (v 9)

means of four samples at each date.

77

Week 4 Week 8 Week 12 Week 17
12:002. r2=0.85. 12:082.. r2=0.84.

 

1.2

Tissue P (% dry mass)

 

 

 

 

 

 

 

Root-medium pH

Acidic WSF (0 0) Neutral WSF (I CI) Basic WSF (v v)

Fig. 3. The effect of root-medium pH on the tissue P of impatiens grown with four
irrigation-water sources and three water-soluble fertilizers (WSF) at 4, 8, 12, and 17
weeks after planting. Filled symbols are hydrated lime treatments and hollow symbols
are carbonate lime treatments. The solid line (——~) represents the predicted tissue P
content based on Eq. [1] and the dotted line ( """ ) represents the minimum recommended
tissue P content. R2 values were calculated as 1-SS,¢._.,idua,/SScorrected m, and remaining
statistical analyses of the individual parameters are presented in Table 3. Data are
means of four samples at each date.

78

Hydrated Lime Carbonate Lime

 

 

 

4
IWeek 4 r2=o.78 i; r2=o.69;
3 L Jr J
. «O
1 L . .‘L O O _
0 F L 1 1 1 ‘r 1 1 1 1 7
:Week 8 r2=o.76 :; r2=o 57
3 3 {— 1
(I) . .. .
m 2 - __ V _
m . .. -4
E L :0 e :
1 r -~ -
3‘ i """""""""""" : t' """"""""""""
‘U L 4L 1
o O 1* 1 l l l 1 l l
g _Week 12 r2=o.32 r2=o 69
8 3 r i: 1
. V .. J
a) 1 -~ «
3 2 7 “CM 1
(I) .
.9. ~
*—

..L
Y I
.0

 

 

 

 

 

 

O 100 200 O 100 200
Applied Ca2+ concentrations (mg/liter)
Acidic WSF( CO ) Neutral WSF ( I D) Basic WSF (v v)

Fig. 4. The effect of applied Ca2+ concentration on the tissue Ca of impatiens grown with
four irrigation-water sources and three water-soluble fertilizers (WSF) at 4, 8, 12, and
17 weeks after planting. The solid line (--) represents the predicted tissue Ca content
based on linear regression analysis and the dotted line ("") represents the minimum
recommended tissue Ca content. R2 values were calculated as l-SSmidw/Ssmmed ml,
and remaining statistical analyses of the individual parameters are presented in Table
4. Data are means of four samples at each date.

7

\O

1 6 Hydrated Lime Carbonate Lime

 

 

 

 

1 Week 4 r1’=0.83T r2=0.741
1.2 a + —
F 4» 4
0.8 l" I Ti— 7
. 41.0 <
0.4 — —- 4
0 0 .Week 8 r2=0.74 r2=0.541
1.2 — —- ~
6‘ .- 0 1
V
g 0.8 — —- —
E . O .. .
E‘ 0.4 -e -— -
1: ........................ -1 ....................... s
\O l l l l L J 441 L 1 1 1 l L l l
O
B” 0'0 LWeek12 r2=0.83,_ r2=0.281
2 1.2 r 1 —
a) , . .
3 i V
.8 0'8 7 “W ‘
'— 1. .1» .
0.4 T. T” T
00 _Week17 r2=0.81T r2=0.27‘
1.2 — —— —
i v "_ L
0'8 W W
F .. .
0.4 b “r a
.0 ..................... ..L ....................... ..

 

 

 

 

O
0 20 40 60 80 O 20 40 60 80100
Applied Mg2+ concentrations (mg/liter)
Acidic WSF (I 0) Neutral WSF ( I Cl) Basic WSF ( v V)

Fig. 5. The effect of applied Mg2+ concentration on the tissue Mg of impatiens grown
with four irrigation-water sources and three water-soluble fertilizers (WSF) at 4, 8, 12,
and 17 weeks after planting. The solid line (—) represents the predicted tissue Mg
content based on linear regression analysis and the dotted line ("") represents the
minimum recommended tissue Mg content. R2 values were calculated as 1-
SSmidmfl/SScorrected tom, and remaining statistical analyses of the individual parameters are
presented in Table 5. Data are means of four samples at each date.

80

Week 12 Week 17

  
  
   

 

1.2
r2: 0.73 .. r2: 0.69‘
1.0 ~
0.8
0.6

0.4

Tissue S (% dry mass)

0.2

 

 

 

 

 

0.0 l l 1 L T l l l J 1 l l l l l l l
0 30 60 90120 0 30 60 90120 O 30 60 90120 0 30 60 90120150

Applied 804-8 (mglliter)

 

Acidic WSF ( I O ) Neutral WSF ( I D ) Basic WSF ( v v)

Fig. 6. The effect of applied SO4-S concentration on the tissue S of impatiens grown with
four irrigation-water sources and three water-soluble fertilizers (WSF) at 4, 8, 12, and
17 weeks after planting. Filled symbols are hydrated lime treatments and hollow
symbols are carbonate lime treatments. The solid line (—) represents the predicted
tissue S content based on Eq. [1] and the dotted line ("") represents the minimum
recommended tissue 8 concentration. R2 values were calculated as 1-SS,,,,m,,,/SScommd
ml, and remaining statistical analyses of the individual parameters are presented in
Table 6. Data are means of four samples at each date.

SECTION IV

THE EFFECT OF ROOT MEDIA ON
ROOT-ZONE pH, CALCIUM, AND MAGNESIUM
MANAGEMENT IN CONTAINER
WITH IMPATIENS

Journal of the American Society for Horticultural Science
Accepted for publication: 28 Oct. 1996

The Effect of Root Media on Root-Zone pH, Calcium, and Magnesium Management

in Containers with Impatiens

William R. Argol and John A. Biembaum2

Department of Horticulture, Michigan State University, East Lansing, MI 48824-1325

Received for publication . Accepted for publication . We acknowledge
the Michigan Agricultural Experiment Station, Bedding Plants Foundation, Inc., Fafard,
and the Western Michigan Bedding Plant Association for supporting this research. Plant
material was provided by the Ball Seed Company, West Chicago, Illinois, and plant
shoot-tissue analysis was provided by the Fafard Analytical Services, Athens, Georgia.
The use of trade names in this publication does not imply endorsement of the products
named or criticism of similar ones not mentioned.

‘ Former Graduate Research Assistant. Current address, Blackmore Company, Belleville,
Mich.

2 Associate Professor.

Abbreviations: CEC, cation exchange capacity; EC, electrical conductivity; IWS,
irrigation-water source; NS, nutrient solution; PNC, preplant
nutrient charge; R0, reverse osmosis; SME, saturated media

extract; WSF, water-soluble fertilizer

81

82
Soils, Nutrition, and Fertilizers

The Effect of Root Media on Root-Zone pH, Calcium, and Magnesium Management

in Containers with Impatiens

Additional index words. Cation exchange capacity, coir, irrigation-water source,
rockwool, sphagnum peat, soilless media, subirrigation,

water-soluble fertilizer

Abstract. Hybrid impatiens (Impatiens Wallerana Hook. F.) were planted in six root
media containing either 70% (by volume) rockwool, coir, or 4 types of sphagnum peat
and 30% perlite. The six media varied in cation exchange capacities (CBC) (from 5 to 76
meq-L") and the amount of a dolomitic hydrated lime (Ca(OH)2 and Mg(OH)2 at O to 4.5
kg-m‘3) required to obtain an initial pH of z6.0. Two additional treatments were produced
by using a dolomitic carbonate lime (CaCO3 and MgCO3) at 8.4 kg-m'3 instead of the
hydrated lime in two of the sphagnum peat media. Plants were subirrigated for 17 weeks
using three nutrient solutions (NS) that contained N-P-K at 200-20—200 mg-L’l but had a
variable NH4 : NO3 ratio, Ca2+, and Mg2+ content. The NS were designed to produce
either acidic, neutral, or basic reactions in the medium. In media containing the hydrated
lime, the NS was the primary factor controlling medium pH. However, within each NS
treatment, the media did have some effect on buffering the pH over time. There was a
linear increase in shoot-tissue Ca and Mg as the applied concentration of Ca2+ increased
from 18 to 156 mg'L"; and that of Mg”, from 5 to 56 mg-L". Linear regression analysis
of shoot-tissue Ca and Mg based on their concentration in the NS indicated a similar
overall decrease in the Ca and Mg supply in all six root media over time. For plants
grown in media containing the carbonate lime, shoot dry weight was similar to that of

plants grown in the same media with hydrated lime. The presence of the carbonate lime in

83
the media increased the pH buffering capacity against decreasing pH with the acidic and

neutral NS, but not against increasing pH with the basic NS. In the media containing the
carbonate lime and given the acidic NS, both root-medium and shoot-tissue Ca and Mg
increased by weeks 12 and 17 compared to that of the same medium containing the
hydrated lime. There were minimal differences in root-media and shoot-tissue Ca and

Mg between lime treatments when given the neutral or basic NS.

A number of sources interact to affect the nutrient supply of container root media
throughout crop production (Argo and Biernbaum, 1996a). However, not all sources
affect the nutrient supply simultaneously or with equal intensity. This is especially true
for Ca” and Mgzi nutrition, where the sources can include exchange sites associated with
the cation exchange capacity (CEC) of the medium, liming materials, and the irrigation-
water source (IWS) and water-soluble fertilizer (WSF) that make up the nutrient solution
(NS). Any discussion of Ca2+ and Mg2+ nutrition also must include pH management
because of the direct or indirect effects the Ca2+ and Mg” sources have on media pH.

The original Cornell peat-lite mixes contained 50% peat by volume (Boodley and
Sheldrake, 1972). The three major types of peat used to produce container media are
sphagnum, hypnum, and reed sedge (Bunt, 1988; Nelson, 1991; Puustjarvi and
Robertson, 1975) and reflect the parent material of the peat. In general, sphagnum is the
most common peat type used in container root media.

The CEC of peat often is associated with the pH and nutrient buffering capacity
and are due to the pH-dependent exchange of cations with H+ from organic acid
functional groups on the peat particles. For example, Helling et al. (1964) found that the
CEC of a sphagnum peat increased by 140 meq'L‘1 as the pH increased from 3.5 to 8.0.

The ratio of H+ to cations bound to the peat also changes with increasing pH. At a pH of

84
3.7, 4.5, 5.5, or 7.8, acid sphagnum peat is 100%, 50%, 30%, or 0% H+ saturated,

respectively (Lucas et al., 1975; Puustjarvi and Robertson, 1975). Bunt (1988) reported
that the CEC of peat largely indicates the potential for divalent ions adsorption (Ca2+ and
Mg“), with most monovalent cations (NHf-N, K", Na+) remaining water-soluble.

The CEC of peat on a weight basis is much higher than that of mineral soils. For
example, Lucas (1982) reported that the CEC of a sphagnum peat was 1000 meq-kg‘l
while that of a loam mineral soil was 120 meq-kg". However, because of the low bulk
density of the sphagnum peat, the effective CEC measured on a volume basis was 40%
less than that of the mineral soil (80 meq-L‘l for the peat vs. 140 meq-L‘l for the mineral
soil). Puustjarvi (1982) reported a linear increase in the CEC of sphagnum peat from 45
meq-L’l to 130 meq-L’I as the degree of decomposition increased from H1 to H5 as
measured with the von Post scale (Puustjarvi and Robertson, 1975). The overall increase
in CEC was associated with both a higher CEC of the more degraded peat itself (Hl peat
was 1000 meq-kg", H5 peat was 1240 meq-kg") as well as an increase in the bulk density
with greater decomposition (H1 peat was 45 kg-m", H5 peat was 105 kg-m").

Other materials such as perlite, polystyrene, or rockwool (RW) have minimal
CBC and are included in container media to increase aeration or water-holding capacity
(Argo and Biernbaum, 1994; Nelson, 1991). Pine or hardwood bark, coconut mesocarp
pith (coir), or expanded vermiculite are added to container media for aeration and water-
holding capacity but each also has significant CEC (Bunt, 1988; Nelson, 1991).
Researchers suggest that an adequate CEC is desired in a container medium to buffer it
from sudden changes in pH and nutrient concentrations (Biernbaum, 1992; Bunt, 1988;
Nelson, 1991). However, only limited information exists on how medium CEC affects
long-term pH, Ca“, and Mg“ management under production conditions.

Liming materials (CaCO3, CaCO3 and MgCO3, Ca(OH)2, Ca(OH)2 and Mg(OH)2)

are added to a soilless root medium to neutralize acidity, increase pH to a level acceptable

85
for plant growth, and provide a source of Ca2+ and Mg”. Incorporating sufficient lime

into a soilless root medium to obtain an initial pH range of 5.5 to 6.4 is recommended
(Nelson, 1991; Peterson, 1981; Warncke and Krauskopf, 1983). The amount of liming
material (incorporation rate) required to obtain an equilibrium pH of 6 in the root medium
depends not only on the components used to produce the medium, but also on the liming
material’s reactivity and particle size (Argo and Biernbaum, 1996b; Chapin, 1980; Gibaly
and Axley, 1955; Schollenberger and Salter, 1943; Sheldrake, 1980; Williams et al.,
1988) as well as the surface area (Parfitt and Ellis, 1966). Argo and Biembaum (1996b)
proposed that not all the liming material incorporated into a soilless root medium may
have reacted once an equilibrium pH is reached. Residual or unreacted lime that
remained in the medium after the equilibrium pH was reached was a significant source of
long-term pH, Ca2+, and Mg2+ buffering capacity when using an acidic NS containing,
low Ca“ and Mg” in one peat-based medium (Argo and Biernbaum, 1996a).

The NS composed of an [W S and WSF and applied to a root medium interacts to
affect the pH and nutrient concentrations two ways: directly (nutrient concentration
applied to the root medium) and through fertilizer reaction on root-medium pH. With
NO3'-N fertilization, the medium pH tends to increase because of OH' or HCO,‘
secretion associated with root ion uptake. In comparison, with NHf—N fertilization,
the medium pH tends to decrease because of H+ secretion during root ion uptake and
the bacterial nitrification of the NHf—N to the NO3'-N form within the medium, which
also releases H+ (Barker and Mills, 1980; Bunt, 1988; Hawkes et al., 1985;
Marschner, 1986; Nelson, 1991). Argo and Biembaum (1996b) found that the degree
of change caused by a NS depended not only on the NH,,:NO3 ratio, but also the
alkalinity concentration in the IWS and the presence or absence of residual lime in the

medium.

86
In production of container-grown crops, it is no longer acceptable to manage the

pH and macronutrient concentrations in the root medium and plant shoot-tissue with high
WSF concentrations and high leaching rates (Biernbaum, 1992). Irrigation systems that
minimize or eliminate water and fertilizer runoff into the environment currently exist.
Optimizing pH, Ca2+, and Mg2+ management of low- or nonleaching irrigation systems
requires an understanding of how factors such as media, lime, IWS, and WSF interact
during production. The objectives of this research were to investigate how NS composed
of three combinations of IWS and WSF interact with root media requiring different lime
incorporation rates to affect root-medium pH, Ca2+, and Mg2+ management under
production conditions.
Materials and Methods

Expt. 1 included 18 treatments composed of six types of media and three types of
NS combined in a 6 x 3 factorial arrangement. Expt. 2 included 12 treatments composed
of two types of media, two types of lime, and three types of NS combined in a 2 x 2 x 3
factorial arrangement. Six of the 12 treatments from Expt. 2 were the same as those in
Expt. 1. At each sampling date, four pots from each treatment (two pots from each of two
greenhouse sections) were sampled. Replication was made between greenhouse sections,
while the two pots taken from the same greenhouse section were treated as subsamples
for statistical analysis.

Soil test data were analyzed using SAS's analysis of variance (ANOVA)
procedures (SAS Institute, Cary, NC.) in Expt. 1 as a 6 x 3 factorial and in Expt. 2 as a 2
x 2 x 6 split-plot factorial, with lime as the main plot and the other factors as subplots at
each sampling date. Medium EC and nutrient concentration data were transformed to
log(observed + l) for the ANOVA because of differences in sample variance between
treatments. Time was not included in the ANOVA because of lack of homogeneity of

variance over time. Relationships were developed between the concentration of Ca2+ and

87
Mg” in the NS and shoot-tissue Ca and Mg using SAS’s linear regression procedure

(REG). Significant differences in the slope and intercept between sample weeks was
tested using a multiple regression model in SAS’s general linear model procedure
(GLM).

Expt. 1. The six root media were composed of 30% perlite (by volume) blended
with one of the following: medium grind RW (Partek North American, Inc., Brunswick,
Ohio); coconut coir pith (Coir) (Scotts, Marysville, Ohio); F isons black bale professional
grower grade Canadian sphagnum moss peat (Peat 1) (Sun Gro Horticulture, Bellevue,
Wash); Fafard Trump Ace professional grower grade Canadian sphagnum moss peat
(Peat 2) (Fafard, Anderson, SC); Fafard Majestic retail fine Canadian sphagnum moss
peat (Peat 3); and Fafard Genuine retail extra fine Canadian sphagnum moss peat (Peat
4). Peats 1 and 2 were long-fibered with little dust (von Post scale 1-2; Puustjarvi and
Robertson, 1975) and peats 3 and 4 were more degraded with short fibers and large
amounts of dust (von Post scale 34). Because of high pH (> 8.5), the unamended RW
was soaked in 0.5 N HCl for 5 min to remove any residual alkaline material, thoroughly
rinsed in reverse osmosis (RO) purified water, and allowed to air dry for three days
before blending into media.

Sufficient amounts of a microfine dolomitic hydrated lime (Ca(OH)2 and
Mg(OH)2 with 34% Ca and 20% Mg, and a CaCO3 equivalent of 169, National Lime
and Stone, Findlay, Ohio) in which 97% of the material passed a 45-pm (#325) screen
were added to increase the pH of the medium to 5.8 to 6.4. Because of the different
lime requirements of the six media, the amount of hydrated lime added per m3 was RW
(0 kg), coir (0.5 kg), peat 1 (1.5 kg), peat 2 (1.6 kg), peat 3 (2.3 kg), and peat 4 (2.7
kg). These incorporation rates added to the six media, respectively, Ca2+ at 0, 0.2,
0.5, 0.5, 0.8, and 0.9 kg-m”; Mg2+ at O, 0.1, 0.3, 0.3, 0.5, and 0.6 kg-m'3; and a CaCO3
equivalent of O, 0.9, 2.6, 2.7, 3.9, and 4.6 kg-m‘3.

88
In addition to the lime, a preplant nutrient charge (PNC) consisting of Ca(NO,)2,

KN03, triple superphosphate (ON-19.8P-OK), and gypsum at 0.6 kg-m" each; MgSO4 at
0.3 kg-m‘3; fritted trace elements (FTE 555, Scotts, Marysville, Ohio) at 0.07 kg-m’3;
and a wetting agent (Aquagro 2000 L, Aquatrols, Pennsaulken, NJ.) at 0.2 L-m” were
incorporated into all media at mixing. Sufficient RO purified well water was added to
bring the moisture content of the medium to 40% to 50% of container capacity, and the
medium was allowed to equilibrate for three days before planting. At planting, the six
media had an average pH of 6.0, an EC of 2.4 dS-m“, and 160 NO,'-N, 45 PO4-P, 220
K“, 210 Ca”, 110 Mg”, and 145 804-8 (mg-L“), as measured with the saturated media
(SME) analysis with R0 water as the extractant (W arncke, 1986).

Nutrient solutions (IVS). The NS concentration of N-P-K was maintained at a
constant 200-20-200 mg'L'l for the duration of the experiment. The three NS varied in
NHf-N, Ca”, Mg”, Na+ and 804-8 concentrations. Nutrient solution 1 (NS 1) was a
WSF made from KNO,, K2804, NH4H2P04, NH4NO3, and urea that contained 50% NH:-
N with 0 Ca”, 0 Mg”, 0 Na+, and 42 804-8 (mg-L") mixed with R0 purified well water
that had a pH of 5.5; an EC of 0.1 dS-m"; 15 Ca”, 5 Mg”, 27 Na“, 1 804-8 (mg-L"); and
a titratable alkalinity to pH 4.5 (Chau, 1984) of <20 mg CaCO3-L°'. Nutrient solution 2
(NS 2) was a WSF made from Ca(NO,)2, KHZPO,” KNO3, Mg(NO3)2, and MgSO4 that
contained 3% NHf-N with 100 Ca”, 50 Mg”, 0 Na”, and 3 804-8 (mg-L") mixed with a
blend of well and R0 water (1:15 by volume) that had a pH of 6.7; an EC of 0.3 dS-m";
52 Ca”, 16 Mg”, 24 Na“, and 10 804-8 (mg-L"); and a titratable alkalinity to pH 4.5 of
120 mg CaCO,-L". Nutrient solution 3 (NS 3) was a WSF made from KH2P04, KNO3,
NaNO3, and NH4NO3 that contained 25% NHf-N with 0 Ca”, 0 Mg”, 62 Na", and 0
804-8 (mg°L") mixed with the same water as that used for NS 2. Micronutrients (Fe,

Mn, Zn, Cu, B, and M0) were added to all nutrient solutions with a commercially

89
available blended chelated material (Compound 111 [1.50 Fe-0.12 Mn-0.08 Zn-O.ll Cu-

O.23 B-O.11 Mo], Scotts, Marysville, Ohio) at a constant 50 mg-L".

The WSF used to make the NS 1, NS 2, and NS 3 were designed to produce either
an acidic, basic, or neutral reaction in the media, respectively, and were based on work by
Argo and Biembaum (1996a). The type of reaction produced by the WSF was calculated,
with values for the reaction produced by the individual salts obtained from Hawkes et al.
(1985) and Young and Johnson (1982) multiplied by the percentage that each salt
contributed to the total WSF weight. The value obtained for each WSF was used as an
estimate of the type (either acidic or basic) and strength (in kg/ 1000 kg of fertilizer) of
reaction produced. Based on these calculations, NS 1 (acidic NS) had an acidity of 199
kg/ 1000 kg, NS 2 (basic NS) had a basicity of 175 kg/ 1000 kg, and NS 3 (neutral NS)
had a basicity of 2 kg/l 000 kg.

Expt. 2. A dolomitic carbonate lime (CaCO3 and MgCO3, with 22% Ca and 13%
Mg, and a CaCO3 equivalent of 108, National Lime and Stone, Findlay, Ohio) in which
60% of the material passed a 75-um (#200) screen was incorporated at 8.4 kg-m‘3 into
media containing peats 1 and 4. At this incorporation rate, the carbonate lime added Ca”
at 1.8 kg°m'3, Mg” at 1.1 kg°m'3, and a CaCO3 equivalent of 9.1 kg'm'3 to each root
media. The lime incorporation rate used in Expt. 2 was not based on the lime
requirement of the two media. In addition to the carbonate lime, the same PNC and
wetting agent used in Expt. 1 were incorporated at mixing. These two treatments were
compared to the same media treatments containing the hydrated lime from Expt. 1. At
planting, the two media containing the carbonate lime had an average pH of 4.8, an EC
of 2.4 dS'm", and 170 NO3‘-N, 60 PO4-P, 180 K+, 170 Ca”, 140 Mg”, and 160 804-8
(mg'L'l), as measured with the SME analysis with R0 water as the extractant (Warncke,

1986).

90
Plant culture. The experiment was conducted starting 15 Feb. 1995 at Michigan

State University, East Lansing, in two well-ventilated glass greenhouse sections with
constant air circulation and cement floors. One hybrid impatiens plug (cv. Super Elfin
Violet) from a size 512 plug tray was planted into a 9-cm-tall by 12.5-cm-wide (0.75-L)
plastic pot containing medium with one of the two lime types. Twenty-five pots of each
medium treatment were placed on three flood subirrigation bench sections in each of the
two greenhouses. Where applicable, both lime types were placed on the same bench
section.

Plants on each bench section were irrigated independently, with the time to
irrigate determined gravimetrically when the average mass of three pots containing plants
and medium from each treatment reached a target weight based on a loss of 40% to 50%
of the available water. The same three pots were checked daily for the target weight, and
when it was reached, NS were applied. During an irrigation, benches were filled with NS
from a 70-L reservoir for 2 min to a maximum depth of 2.5 cm and drained in 6 min to
the same reservoir. The difference between the mass of the pots before and after the
irrigation was the NS absorbed. The amount of nutrients applied per pot was calculated
as the sum of the absorbed NS multiplied by the concentration. The NS in the 70-L
reservoirs were prepared fresh weekly.

Media physical and chemical characteristics. Medium moisture holding
characteristics were determined in the 9-cm-tall by 12.5-cm-wide pots using the method
outlined by White and Mastalerz (1966). The blended medium CEC was determined
with air-dried, acid-washed media using the method outlined by Rund (1984). Barium
from 0.5 N Ba(OAc)2 was used as the replacement ion for the H” saturated media.
Cation exchange capacity expressed on a volume measurement was calculated by

multiplying the bulk density by the CEC measurement based on weight.

91
Sampling technique. Root media were sampled initially and collected from four

pots (two per treatment from each bench section) at 1, 4, 8, 12, and 17 weeks after
planting. All the medium was removed from each pot and separated horizontally into two
samples, one containing the top 2.5 cm (top layer), and the other containing the remaining
medium from the pot (root zone). Nutrients contained in each medium sample were
tested using the SME method with R0 purified water as the extractant (Warncke, 1986).
Only EC was measured in the top-layer sample, while pH, EC, NO3'-N, NHf-N, PO4-P,
K2 Ca”, Mg”, and 804-8 were measured in the root-zone sample. Medium pH was
determined by inserting the ion-specific electrode directly into the saturated medium
before extraction, and EC and macronutrients were measured in the extracted solution.
Medium BC was determined with a platinum electrode at a standard 25 °C; Mg was
determined colorimetrically (magnesium blue, Technicon Instruments, Tarrytown, N.Y.);
and Ca” was determined using emission spectroscopy by the Michigan State University
Soil and Nutrient Testing Laboratory. Medium CEC also was measured in the top layer
and root zone at the week 17 sampling date using the method outlined previously.

Shoot dry weight and shoot-tissue nutrient analysis were determined for four
plants per treatment at 4, 8, 12, and 17 weeks afier planting. At week four, the entire
plant was used in the sample. For the remaining plants, all shoots were pinched back,
leaving one intemode per stem and four to six stems per plant. At all subsequent
sampling dates, only growth after the previous pinch was sampled, and the remaining
plants were cut back to the week-four pinch level. Shoot-tissue macronutrients and
micronutrients (Fe, Mn, Cu, Zn, B, and Mo) were determined by plasma emission
spectroscopy (Fafard Analytical Laboratory, Athens, Georgia).

Results and Discussion
Media physical and chemical characteristics. The six root media used in this

experiment had air space ranging from 18% to 28% and a total water-holding capacity

92
from 49% to 63% of the 0.75-L pot at container capacity (Table 1). These values were

within established guidelines for container media (Bunt, 1988).

Cation exchange capacity of the media used in this experiment ranged from 34 to
639 meq-kg'l (Table 1). However, because of the low bulk density of the medium, the
CEC on a volume basis ranged from 5 to 76 meq-L“. The effective cation exchange sites
of the media in the pot was lower still because the pot size was 0.75 L and the top 2 to 3
cm that contains 35% of the medium were without roots. Nutrients contained in the top
layer of subirrigated pots are generally unavailable to the plant (Argo and Biernbaum,
1996a; Yelanich, 1995). Any cation exchange sites associated with the medium
contained in the top layer probably will not affect the remaining medium within the pot
with subirrigation. In fact, when the CEC of media contained in the top-layer sample was
tested after 17 weeks, there was a 5% to 20% decrease (by weight) compared to the same
media at planting (data not shown). In comparison, the CEC of the root zone did not
change between planting and week 17.

Plant growth. In Expt. 1, new shoot growth was affected by media and NS (Fig.
1). However, except for plants grown in the RW media, the differences in shoot dry
weight were not consistent across NS or between the sampling dates. There were
minimal differences in the shoot dry weight of plants grown with the basic NS than either
the acidic or neutral NS. In Expt. 2, the growth of plants in media containing the
carbonate dolomitic lime was similar to that of plants grown in the same media with
hydrated lime, but there were media differences similar to those measured in Expt. 1 (data
not shown). In comparison, Argo and Biembaum (1996a) measured only small
differences between impatiens grown under similar conditions using 24 combinations of
lime, IWS, and WSF but with a single root medium.

Plants grown in the RW medium were much smaller than those grown in the other

root media (Fig. 1) with all three NS. The reason for the limited growth is unclear but

 

93
may have been due to poor rooting of the plugs into the RW medium. Several species

including African violet, Chrysanthemums, Easter lily, gerbera, gloxinia, kalanchoe, and
poinsettia were grown in 100% acid-washed RW with subirrigation and were of equal
size and quality to those grown in commercially available Peatlite media (Biernbaum,
unpublished data; Yelanich, 1995). However, in those experiments, a PNC and wetting
agent were not incorporated into the RW medium before planting. The initial nutrient
concentrations from the PNC were slightly higher in the RW media (2.8 dS-m") than in
the other media (remaining media average of 2.3 dS-m"), but were within normally
acceptable limits (Warncke and Krauskopf, 1983). Wetting agents can be phytotoxic to
impatiens (Bhat et al.,l989) which may have caused the limited growth of the RW
treatments plants in this experiment.

Water and fertilizer applications. Excluding the RW treatments, the volume of
water applied ranged from 6.1 to 7.3 L per pot over the 17 weeks of the experiment
(Table 2). Because the N-P-K concentrations in the NS were constant, the amount
applied was similar and ranged from 1.4 to 1.8 g N and K”, and 0.23 to 0.26 g PO4-P per
pot, including the PNC fertilizers (data not shown). In comparison, the concentrations of
Ca” and Mg” in the NS varied by a factor of almost 10, and the amount of Ca” and Mg”
incorporated with the lime also varied because of the different lime requirements of the
six media. The total amount applied ranged from 0.5 to 1.9 g Ca” and 0.14 to 0.87 g
Mg” per pot in Expt. 1 (Table 2). In Expt. 2, the incorporation of the dolomitic carbonate
lime increased the total amount of Ca and Mg applied per pot to 1.7 to 2.5 g Ca” and 0.9
to 1.2 g Mg” per pot and was similar for the peat 1 and peat 4 media with each NS.

Argo and Biembaum ( 1996a) found that impatiens grown with shoot-tissue Ca
and Mg concentrations as low as 0.4% and 0.2%, respectively, produced a similar amount
of dry mass compared to impatiens grown with shoot-tissue Ca and Mg concentrations at

2.5% and 1.0%, respectively. Based on the amount of shoot tissue produced, sufficient

94
Ca and Mg were applied to the crop to maintain the highest shoot-tissue Ca and Mg

concentrations (2.5% and 1%, respectively) for the duration of the experiment in all
treatments (excluding the RW treatments). For example, in Expt. 1, the amount of Ca
required as a percentage of the total Ca applied would have averaged 36% (33% to 46%)
with the acidic NS, 25% (23% to 33%) with the neutral NS, and 16% (14% to 20%) with
the basic NS. For Mg, the amount required as a percentage of the total Mg applied would
have averaged 38% (25% to 65%) with the acidic NS, 27% (20% to 41%) with the
neutral NS, and 16% (12% to 19%) with the basic NS. With the RW treatments, the
amount of Ca as a percentage of the total Ca applied required to maintain 2.5% shoot-
tissue Ca would have been 40%, 26%, and 10% for the acidic, neutral, and basic NS,
respectively. However, with Mg, the acidic NS did not supply enough for the 1% shoot-
tissue Mg, but the other two treatments supplied excess Mg so that the percentage of the
total amount applied would have been 57% and 11% with the neutral and basic NS,
respectively.

Root-zone pH. In Expt. 1, the initial pH of the media ranged from 5.7 in the peat
1 medium to 6.4 in the peat 3 medium. By week 1, the pH of all media had increased and
ranged from 6.3 in the peat 4 medium to 6.8 in the RW medium, as averaged over the NS
(Fig. 2, Table 3). In general, the primary factor controlling medium pH in Expt. 1 was
the NS (Fig 2, Table 3), which was affected by the percentage of NHf-N in the WSF and
the alkalinity concentration in the IWS (Argo and Biernbaum, 1996a). Within each NS
treatment, the media did have some effect on buffering pH. For example, the pH of the
coir medium given acidic NS decreased most between weeks 1 and 4, but was similar to
that of the other root media thereafter. With the neutral NS, the highest pH was
maintained in media containing the more-degraded peat (peat 3 and 4), while the coir

media maintained the lowest pH. With the basic NS, only media containing peat 4

95
temporarily slowed the increase in root-medium pH, but by week 17, the pH was similar

to that of the coir and RW media.

In Expt. 2, media containing the dolomitic carbonate lime at 8.4 kg°m'3 had an
average pH of 4.8 at planting, which increased to an average of 6.0 by week 1, similar to
the average of 6.3 in the same media containing the hydrated lime (Fig. 3). Afier week 1,
the effect that the type of lime incorporated into the medium had on the long-term pH
buffering capacity depended on the type of NS applied (Fig. 3, Table 4). With the acidic
NS, peat type had minimal effect on pH buffering. Instead, the residual lime was the
primary factor buffering medium pH through week 12. With the neutral NS, peat type had
some effect on pH buffering capacity, but the peat effect could be negated with residual
lime contained in the medium. With the basic NS, lime type had minimal effect on pH
buffering. Instead, the primary factor buffering the medium was the peat type (Fig. 3,
Table 4).

Argo and Biembaum (1996a) suggest that reliance on residual lime for pH
buffering is risky because it cannot be measured with the standard SME analysis. The pH
buffering loss in the peat 4 medium given the acidic NS after the week 12 sampling date
indicates that the residual lime contained in the medium may have been depleted. Since
the peat 4 medium had a higher initial lime requirement than that of the peat 1 medium to
obtain the same pH, there would have been less residual lime for long-term buffering. An
alternative to reliance on residual lime for pH buffering may be to use a WSF with <40%
to 50% NHf-N, especially for long-term crops grown with an IWS containing an
alkalinity at <120 mg CaCO3'L".

Calcium. In Expt. 1, initial root-medium Ca” concentrations ranged from 127
mg-L" in peat 1 media to 384 mg-L'l in the coir media at planting (data not shown).
However, by week 1, root-medium Ca” concentrations had decreased to an average of

44% of the initial concentration (Fig. 2, Table 3). After the week 1 sampling date, the

96
Ca” concentration remained below the suggested acceptable level (80 mg-L") with the

acidic WSF, but was at or above the recommended level with the neutral and basic WSF
for the remainder of the experiment, as measured with the SME (Fig. 2) (Warncke and
Krauskopf, 1983). The Ca” concentration in the RW medium was higher than that of the
other root media from week 8 until the end of the experiment with the three NS.

With the six media from Expt. 1, there was an overall linear increase in shoot-
tissue Ca as the applied Ca” concentrations in the NS increased from 18 to 156 mg-L'l
(Fig. 4, Table 5). The intercept value reflects the Ca supplied by the root medium if no
additional Ca” were applied in the NS. The decrease in the intercept value and increase
in the slope between the weeks 4 and 17 sampling date indicates an overall decrease in
the amount of Ca supplied by the medium over time (Table 5). The improvement in the
r2 between the week 4 and week 17 analyses indicates a decrease in the influence of the
media treatments on Ca uptake over time.

A linear trend with only three treatment levels does not necessarily indicate a
linear relationship. However, a similar linear relationship between the concentration of
Ca” in the NS and shoot-tissue Ca was reported by Argo and Biembaum (1996a) with
impatiens grown with 12 NS. The results from this experiment add further support to the
conclusion of Argo and Biembaum (1996a) that: 1) the main factor affecting the uptake
of Ca into the plant was the concentration of Ca” in the NS, as affected by both the WSF
and IWS; and 2) other ions in the NS (N Hf-N, K, Mg”, or SO4-S) did not interfere with
uptake.

If the amount of shoot tissue produced during the entire experiment was taken into
account, then the shoot tissue of plants grown in the peat 4 media accmnulated the most
Ca per pot (0.17 g) while those grown in the RW media accumulated the least Ca per pot
(0.05 g), as averaged over the NS treatments. However, it cannot be determined from this

experiment if Ca was more available in the peat 4 media resulting in higher average shoot

97
growth, or if the higher average growth of plants in the peat 4 media resulted in more Ca

uptake compared to that of plants grown in the RW medium.

In Expt. 2, the presence of dolomitic carbonate lime in the peat 1 and 4 media did
not increase their initial Ca” concentration (carbonate lime treatment Ca was 165 mg-L";
hydrated lime treatment average was 155 mg-L") or effect Ca” concentrations through
week 4 compared to the same media with hydrated lime (Fig 3,Table 4). However, after
week 8, Ca” concentrations in media containing the dolomitic carbonate lime increased
with the acidic NS compared to that of the same media with hydrated lime (Fig. 3, Table
4). In comparison, there were no consistent differences in media Ca concentration
between lime types in the media receiving neutral or basic NS. There was a
corresponding increase in shoot-tissue Ca for plants grown in media containing the
carbonate lime and receiving the acidic NS at the weeks 12 and 17 sampling dates
compared to plants grown in the same media containing the hydrated lime (Fig. 5).
Shoot-tissue Ca was similar for both lime treatments for plants grown with neutral or
basic NS.

We interpret the results to indicate that the large amount of residual lime
contained in the medium after the equilibrium pH was reached did not, in itself, buffer the
root-medium Ca concentrations or influence Ca uptake. Instead, the increase in root-
medium and shoot-tissue Ca resulted from the reaction of the acidic NS (50% NHf-N
WSF with R0 water) with the lime. Decreasing the percentage of NHf-N in the WSF
and increasing the alkalinity content of the IWS decreased the overall acidity of the NS
and almost completely negated the residual lime as a Ca source. Similar results were
found by Niemiera and Wright (1986) when nitrification within the medium was
inhibited. Thus, if a less acidic WSF is used in conjunction with a low alkalinity (<120
mg CaCO3-L") and low Ca” IWS in order to better manage root-medium pH, then the

WSF also should contain Ca”. Argo and Biembaum ( 1996a) reported that NS Ca”

98
concentrations at 100 to 160 mg-L'l were sufficient to maintain impatiens shoot-tissue Ca

concentrations at >2% and were independent of the effect of residual lime in the medium.

The linear relationship between the NS Ca” concentration and shoot-tissue Ca
presented in this and other experiments indicates the Ca status of all the shoot tissue
sampled from the plant. Because Ca is immobile in the plant, Ca deficiencies ofien are
localized events (bract edge burn in poinsettias, black heart in celery, blossom end rot in
tomatoes and peppers, leaf edge burn in lettuce) that may occur even when the overall Ca
status of the plant is high (Marschner, 1986). Increasing overall shoot-tissue Ca has
many benefits, including increased stem strength (McDaniel et al., 1986) and resistance
to pathogens (Marschner, 1986), but may not necessarily affect the localized Ca
deficiencies found in many crops (Jacques et al., 1991; Marschner, 1986; Woltz and
Harbaugh, 1985).

Magnesium. In Expt.], initial root-medium Mg” concentrations ranged fi'om 64
mg-L'l in the coir medium to 163 mg-L’l in the peat 4 medium at planting (data not
shown). However, by week 1, root-medium Mg” concentrations had decreased to an
average of 33% of the initial concentration (Fig. 2, Table 3). After the week 1 sampling
date, the Mg” concentration remained below the suggested acceptable level (30 mgL")
with the acidic and neutral NS, but was at or above the recommended level with the basic
WSF for the remainder of the experiment as measured with the SME (Fig. 2) (Warncke
and Krauskopf, 1983).

As with Ca, there was an overall linear increase in shoot-tissue Mg as the applied
Mg” concentration in the NS increased from 5 to 72 mg°L'l (Fig. 4, Table 5). The
intercept value reflects the Mg supplied by the root medium if no additional Mg were
applied in the NS. The decrease in the intercept value and increase in the slope between
the weeks 4 and 17 sampling dates indicates a decrease in the amount of Mg supplied by

the medium over time (Table 5). The improvement in the 1'2 between the week 4 and

99
week 17 analyses indicates a decrease in the influence of the media treatments on Mg

uptake over time. We interpret the results from this experiment add further support to the
conclusion of Argo and Biembaum (1996a) that: l) the main factor affecting the uptake
of Mg into the plant was the concentration of Mg” in the NS, as affected by both the
WSF and IWS; and 2) other ions in the NS (NHf-N, K+, Ca”, or SO4-S) did not interfere
with uptake.

In Expt. 2, the presence of the dolomitic carbonate lime in the peats l and 4 media
increased the medium Mg” concentrations with acidic NS compared to that of the same
media with hydrated lime (Fig. 3, Table 4). In comparison, there were no consistent
differences in the medium Mg” concentration between lime types in the media receiving
the neutral or basic NS. There was a corresponding increase in shoot-tissue Mg
concentration for plants grown in media containing the carbonate lime and receiving the
acidic NS at the weeks 12 and 17 sampling dates compared to plants grown in the same
media containing the hydrated lime (Fig. 5). Shoot-tissue Mg was similar for both lime
treatments for plants grown with the neutral or basic NS. If a less acidic WSF is used in
conjunction with a low alkalinity (<120 mg CaCO3-L") and low Mg” IWS in order to
better manage root-medium pH, it should also contain Mg”. Argo and Biembaum
(1996a) found that NS Mg” concentrations at 30 to 50 mg-L'l were sufficient to maintain
impatiens shoot-tissue Mg concentrations of >1% and were independent of the effect of
residual lime in the medium.

Conclusion. The finer, more degraded sphagnum peats containing large
percentages of fine particles and dust (peat 4) are often not used in commercially
available blend soilless media because of their adverse effects on physical properties
(Bunt, 1988; Puustjarvi and Robertson, 1975). In medium containing peat 4, there was a
decrease in the overall porosity (Table 1), but the percent air space at container capacity

was similar to the other media. The shoot dry mass of plants grown in the peat 4 medium

100
was similar to or greater than those grown in media containing grower grade sphagnum

peats (peat 1 and 2). Neither the soil test data (which included all macronutrients) nor the
shoot-tissue analysis data (which included macronutrients and micronutrients) were
sufficiently different to expect the variation in shoot growth observed in this experiment.
Argo and Biembaum (1995) proposed that the plant grth measured in many
experiments depends on the irrigation management of the medium. If the irrigation
management used in this experiment were different (irrigated on a fixed schedule), then
the amount of dry mass produced by plants grown in the different media probably also
would have been different.

Cation exchange capacity has been the primary focus of pH and nutrient buffering
capacity in soilless container root media (Bunt, 1988; Nelson, 1991). For the six media
tested in this experiment, CEC influenced pH, Ca, and Mg buffering capacity. However,
other sources of buffering capacity existed including the residual lime, which had a much
greater effect on the buffering capacity of the media than did CEC under acidic (pH, Ca,
and Mg buffering) or neutral (pH buffering) conditions. Another source of buffering
capacity not addressed in this study is the fertilizer salts that are concentrated at the root-
medium surface because of salt stratification within the pot. With top watering, these
salts buffered the macronutrient concentration in the root zone for six weeks after
fertilization was stopped with poinsettias (Argo and Biernbaum, 1995).

The pH of some components can be slightly acidic (coir pH is 5.4 to 6.4) to highly
basic (RW pH is 8.5 to 9.5 before acidification). In media containing a large percentage
of these materials, less lime will be needed to increase the starting pH to the suggested
5.5 to 6.4 compared to media using large percentages of an acidic peat. Reducing the lime
incorporation rate also may reduce the amount of residual lime in the medium, which is a
significant source of long-term pH, Ca, and Mg (if dolomitic lime) buffering capacity.

Alternative sources of Ca or Mg, such as gypsum or MgSO4, were not persistent in the

101
medium for more than a few weeks after planting if some leaching occurred or

subirrigation was used (Argo and Biembaum, 1995, 1996a, 1996b). If components that
reduces lime incorporation rates are used in media, a WSF containing a lower percentage
of NHf-N in addition to Ca” and Mg” should be used to prevent the medium’s pH from
falling below the suggested 5.8 to 6.4 (Warncke and Krauskopf, 1983) compared to the
same crop grown in media containing residual lime. The exact percentage of NHf-N in
the WSF to maintain a stable pH depends on the alkalinity concentration in the IWS and
the WSF concentration.

Further study is needed to determine the effects that other components, such as
vermiculite or bark, have on the pH and nutrient buffering capacity of a soilless root
medium. Quantification of the effects that different plant species have on pH and nutrient
management also is needed. Finally, it is not known if the uptake of Ca” and Mg” in
species besides impatiens is affected only by the concentration of those ions in the NS.
Future experiments should be performed with consideration for the interactive effects
WSF has with irrigation-water alkalinity, lime, and root-medium components on
maintaining a stable root-medium pH and supplying Ca” and Mg” (Argo and

Biernbaum, 1996a; Niemiera and Wright, 1986).

Literature Cited

Argo, W.R. and J.A. Biembaum. 1994. Irrigation requirements, root-medium pH, and nutrient
concentrations of Easter lilies grown in five peat-based media with and without an evaporation
barrier. J. Amer. Soc. Hort. Sci. 119:1151-1156.

Argo, W.R. and J.A. Biembaum. 1995. Root-medium nutrient levels and irrigation requirements
of poinsettias grown in five root media. HortScience 30:535-53 8.

Argo, W.R. and J .A. Biembaum. 1996a. The effect of lime, irrigation-water source, and water-
soluble fertilizer on root-zone pH, EC, and macronutrient management of container root media

with impatiens. J. Amer. Soc. Hort. Sci. 121 :442-452.

102
Argo, W.R. and J.A. Biembaum. 1996b. Availability and persistence of macronutrients from

lime and preplant nutrient charge fertilizers in peat-based root media. J. Amer. Soc. Hort. Sci.
1212453-460.

Barker, A.V. and HA. Mills. 1980. Ammonium and nitrate nutrition of horticultural crops. Hort.
Rev. 2:395-423.

Biernbaum, J.A. 1992. Root-zone management of greenhouse container-grown crops to control
water and fertilizer use. HortTechnology 2: 127-132.

Bhat, N.R., T.L. Prince, H.K. Tayama, and SA. Carver, 1989. Effect of Aqua-gro on seed
germination and seedling development of bedding plants. Ohio F lorists' Assoc. Bull. 719: 1-4.
Boodley, J.W. and R. Sheldrake. 1972. Cornell peat-lite mixes for commercial plant growing.

Cornell Ext. Bul. 43.

Bunt, A.C. 1988. Media and mixes for container-grown plants. Unwin Hyman, London.

Chapin, J.K. 1980. The effect of fineness in limestone on the pH of 50:50 peat-vermiculite mix.
Benchmarks 1:7.

Chau, A.S.Y. 1984. Water and salt. p. 617-638. In: S. Williams (ed.) Official methods of analysis
of the association of official analytical chemists. Assoc. of Offic. Anal. Chemists, Arlington,
Virginia.

Gibaly, HE. and J.H. Axley. 1955. A chemical method for the rating of agricultural limestones
used as soil amendments. Soil Sci. Soc. Amer. Proc. 20:301-302.

Hawkes, G.R., D.B. Campbell, A.E. Ludwick, R.M. Millaway, and R.M. Thorup (eds.). 1985.
Fertilizers: A source of plant nutrients, p. 83-110. In: Western fertilizer handbook. 7th ed.
Interstate, Danville, Ill.

Helling, C.S., G. Chesters, and RB. Corey. 1964. Contribution of organic matter and clay to soil
cation-exchange capacity as affected by the pH of the saturating solution. Soil Sci. Soc. Amer.
Proc. 28:517-520.

Jacques, D.J., R.E.J. Boemer, and J.C. Peterson. 1991. The effect of calcium spray on leaf and
bract distortion, boundzunbound calcium ratio, and calcium distribution in two poinsettia

cultivars. J. of Plant Nutr. 14:637-3 52.

103
Lucas, RE, RE. Rieke, J.C. Shickluna, and A.Cole. 1975. Lime and fertilizer requirements for

peats, p. 51 - 70. In: D.W. Robinson and J.G.D. Lamb (eds.), Peat in horticulture. Academic
Press, London.

Lucas, RE. 1982. Organic soils (Histosols). Research Rpt. No. 435. Mich. Agr. Exp. Sta., East
Lanising.

Marschner, H. 1986. Mineral nutrition of higher plants. Academic Press, London.

McDaniel, G.L., E.T. Graham, and K.A. Lawton. 1986. The role of nitrogen and calcium on stem
strength of poinsettia (1986). Research Rpt. 86-15. Univ. of Term. Agri. Exp. Stat.

Nelson, P.V. 1991. Greenhouse operations and management. 4th ed. Prentice Hall, Englewood
Cliffs, NJ.

Niemiera, A.X. and RD. Wright. 1986. The influence of nitrification on the medium solution
and growth of holly, azalea, and juniper in a pine bark medium. J. Amer. Soc. Hort. Sci.
111:708-712.

Parfitt, R.L. and B.G. Ellis. 1966. Studies on Michigan agricultural limestones. Michigan Agr.
Expt. Sta. Quarterly Bul. 49: 12-23.

Peterson, J .C. 1981. Modify your pH perspective. Florist's Rev. 169234-35, 92-93.

Puustjarvi, V. and R.A. Robertson. 1975. Physical and chemical properties, p. 23-38. In: D.W.
Robinson and J .G.D. Lamb (eds.). Peat in horticulture. Academic Press, London.

Puustjarvi, V. 1982. Nature of changes in peat properties during decomposition. p. 5-20. Peat
and Plant Yearbook (1981 - 1982)

Rund, RC. 1984. Fertilizers. p. 8-37. In: S. Williams (ed.) Official methods of analysis of the
association of official analytical chemists. Assoc. of Offic. Anal. Chemists, Arlington,
Virginia.

Schollenberger, OJ. and R.M. Salter. 1943. A chart for evaluating agricultural limestone. J.
Amer. Soc. Agron. 35:955-966.

Sheldrake, R. 1980. Lime source and quantity study on peat-vermiculite. . Benchmarks 1:6-7.

Warncke, DD. 1986. Analyzing greenhouse growth media by the saturation extraction method.

HortScience 21 :223-225.

104
Warncke, D. and D. Krauskopf. 1983. Greenhouse media: Testing and nutrition guidelines.

Michigan State Univ. Ext. Bul. E-l736.

White, J.W. and J.W. Mastalerz. 1966. Soil moisture as related to container capacity. Proc.
Amer. Soc. Hort. Sci. 89:758-765.

Williams, B.J., J.C. Peterson, and JD. Utzinger. 1988. Liming reactions in sphagnum peat-based
growing media. J. Amer. Soc. Hort. Sci. 113:210-214.

Woltz, SS. and BK. Harbaugh. 1985. Effect of nutritional balance on bract and foliar necroses
of poinsettia. Proc. Fla. State Hort. Soc. 98:122-123.

Yelanich, M.V. 1995. Modeling the concentration of nitrogen in the root zone of container-
grown Chrysanthemums. PhD Diss., Michigan State Univ., East Lansing.

Young, R. and F]. Johnson. 1982. Fertilizer products, p.45-68. In: The fertilizer handbook. The

Fertilizer Institute, Washington, DC.

105

Table 1. Average air space (AS), water space at container capacity (CC) in a 9-cm-tall
pot, bulk density (BD), and cation exchange capacity (CEC) of six root media
composed of 70% (by volume) of the material listed below with 30% perlite. Reported
values are the mean of five samples.

 

 

 

AS CC 30 CEC ‘
Root media Percentage by volume kg-m'3 meq‘kg’l meq-L“
Rockwool 28 a Y 49 e 114 a 34 e 5 e
Coir 19 c 63 a 84 c 408 d 34 (1
Peat 1 24 b 56 c 87 c 580 be 50 b
Peat2 23b 61 b 76d 5430 41c
Peat3 19c 62 ab 87c 615 ab 53b
Peat4 18c 52d 119b 6393 76a

 

‘ 0.1 N BaOAc was used to determine the CEC of acid-washed root media.
3' Mean separation by Duncans’s multiple range test, P _< 0. 05.

Table 2. Cumulative water, Ca”, and Mg” applied to plants grown in various media and
nutrient solution (NS) treatments after 17 weeks. The initial nutrient content of the
root medium was included in the values reported below. Data are the mean of three
pots from each treatment.

 

Acidic NS Neutral NS Basic NS

 

 

Applied Applied Applied
water Ca Mg water Ca Mg water Ca Mg

(liter) (g/Pot) (g/POt) (liter) (g/POt) (g/pot) (liter) (g/POt) (g/POt)
Dolomitic hydrated lime (Expt. 1)

Rockwool 4.7 0.3 0.04 4.5 0.5 0.09 5.0 1.0 0.36
Coir 6.5 0.5 0.14 7.0 0.7 0.22 6.1 1.3 0.51
Peat l 6.3 0.7 0.29 6.5 1.0 0.36 6.3 1.6 0.67
Peat 2 6.7 0.7 0.30 6.6 1.0 0.37 6.3 1.6 0.68
Peat 3 6.9 0.9 0.42 7.0 1.2 0.50 6.9 1.9 0.84
Peat 4 7.3 1.0 0.48 7.3 1.3 0.56 6.4 1.9 0.87

Dolomitic carbonate lime (Expt. 2)
Peat 1 6.3 1.7 0.88 6.1 1.9 0.95 6.1 2.5 1.25
Peat 4 6.2 1.8 0.88 6.8 1.9 0.96 6.2 2.5 1.26

 

106

Table 3. Degrees of freedom (df), F-values (A), levels of significance (B), and mean
square error (MSE) from the analysis of variance for the log(observed + 1)
transformed root-zone pH, Ca”, and Mg” concentrations at l, 4, 8, 12, and 17 weeks
after planting in Expt. 1.

 

 

 

Week 1 Week 4 Week 8 Week 12 Week 17
df A B A B A B A B A B
Root-zone pH
Media (M) 5 10.9 "* 10.8 "* 10.9 **‘ 10.9 1'" 7.6 "*
NS2 2 3.6 * 13.0 *" 459.0 *** 867.1 "* 1092.1 *"
MxNS 10 1.7 NS 4.7 "* 5.8 "* 10.3 *** 10.8 "*
MSE 53 0.0426 0.1476 0.0579 0.0469 0.0580

Root-zone Ca”
Media(M) 5 98.6 m 14.4 m 4.8 *1 25.8 m 26.0 m

NS 2 137. **"‘ 164. “”" 141.0 *** 213.1 *** 290.4 “m
7 l
M x NS 10 3.7 " 1.8 NS 2.0 NS 3.3 ** 2.9 *
MSE 53 0.0034 0.0043 0.0075 0.0052 0.0043
Root-zone Mg”

Media (M) 5 5.8 "* 7.3 *"“" 4.6 " 9.7 "* 14.6 H"
NS 2 96.5 H" 51.6 "* 70.0 *** 70.6 *** 133.3 "*
MxNS 10 0.5 NS 3.8 "‘ 4.9 "”" 5.1 **"‘ 5.0 **'"
MSE 53 0.0108 0.0389 0.0417 0.0414 0.0423

 

' Nutrient solution.
”5' " "' ... Nonsignificant or significant at P <0.05, 0.01, or 0.001, respectively.

107

Table 4. Degrees of freedom (df), F-values (A), levels of significance (B), and mean
square of error a and error b from the analysis of variance for the log(observed + 1)
transformed root-zone pH, Ca”, and Mg” concentrations at 1, 4, 8, 12, and 17 weeks
after planting in Expt. 2.

Week 1 Week 4 Week 8 Week 12 Week 17
df A B A B A B A B A B
Root-zone pH

 

 

Lime (L) 1 41.5 NS 71.7 NS 62.1 NS 20.5 NS 104.5 NS
Error a 1 0.0196 0.0130 0.0876 0.3798 0.1716
Media (M) l 3.7 NS 1.0 NS 5.9 " 18.6 *" 35.5 "'"
NS 2 2 14.4 *** 4.4 "‘ 148.5 *" 332.8 *" 669.1 ***
M x L l 0.2 NS 0.2 NS 1.0 NS 5.8 * 22.4 ""
NS x L 2 3.4 NS 4.7 * 16.2 "* 67.3 "* 38.2 "*
M x NS 2 1.0 NS 2.3 NS 20.7 "* 41.9 *** 18.9 "*
M x NS x L 2 1.3 NS 2.0 NS 4.7 * 3.9 * 5.6 *"‘
Error b 34 0.0385 0.0769 0.0654 0.0369 0.0476
Root-zone Ca”
Lime (L) 1 16.0 NS 0.0 NS 228.0 * 21.8 NS 37.2 NS
Error a 1 0.0007 0.0003 0.0001 0.0032 0.0029
Media (M) l 0.5 NS 3.0 NS 3.0 NS 4.0 NS 14.2 *"
NS 2 260.3 *** 61.1 "* 69.6 "* 155.5 *" 138.3 ""‘
M x L l 2.1 NS 0.1 NS 0.7 NS 16.3 "* 4.3 "
NS x L 2 2.1 NS 0.5 NS 7.9 ** 18.4 “* 14.7 ***
M x NS 2 2.4 NS 0.6 NS 0.6 NS 2.3 NS 2.1 NS
M x NS x L 2 0.8 NS 1.5 NS 5.5 *"‘ 6.0 H 3.4 NS
Error b 34 0.0018 0.0052 0.0055 0.0041 0.0059
Root-zone M g”

Lime (L) 1 19.1 NS 0.1 NS 999.6 "* 23.9 NS 29.5 NS
Error a 1 0.0013 0.0096 0.0001 0.0432 0.0653
Media (M) l 2.6 NS 6.8 "‘ 0.2 NS 0.8 NS 3.4 NS
NS 2 86.9 "* 21.6 *" 25.4 *** 32.9 *** 33.8 *"
M x L l 5.3 * 2.6 NS 1.3 NS 9.1 " 2.4 NS
NSX L 2 2.8 NS 1.2 NS 15.0 "* 18.0 "* 19.4 "*
M x NS 2 2.9 NS 5.8 ** 5.3 H 10.5 *** 6.4 *"'
M x NS x L 2 1.0 NS 4.8 "‘ 9.0 *** 4.0 "' 2.6 NS
Error b 34 0.0143 0.0489 0.0369 0.0315 0.0368

 

‘ Nutrient solution.
NS. '. Nonsignificant or significant at P< 0.05, 0.01, or 0.001, respectively.

108

Table 5. Parameters of linear regression analysis for shoot-tissue Ca and Mg based on
the concentration of Ca” and Mg2+ applied in the nutrient solution of plants grown
in six root media containing various amounts of hydrated dolonritic lime (Ca(OH)2
and Mg(OH)2). Plants grown in media containing Peat l and 4 with the dolonritic
carbonate lime (CaCO3 and MgCO3) were not included in the regression analysis.
The number of observations used in the analysis was 36 at week 4 and 72 thereafter.
Data are presented in Fig. 4.

 

 

Week 4 Week 8 Week 12 Week 17 Units
Shoot-tissue Ca
Intercept 1.17 i 0.141 a" 1.03 i 0.07 a 0.72 :t 0.09 b 0.41 i: 0.07 c Dry mass (%)
Slope 0.004 :t 0.001 a 0.007 10.001 b 0.009 t 0.001 c 0.010 1 0.001 c Dry mass (%)/mg'liter'l
Shoot—tissue Mg
Intercept 0.62 i 0.07 a 0.49 i- 0.03 b 0.38 i 0.03 c 0.28 i 0.03 (1 Dry mass (%)
Slope 0.003 3: 0.002 a 0.005 i 0.001 0.005 t 0.001 0.006 3: 0.001 b Dry mass (%)/mg-liter'l
ab ab

 

‘ Ninety-five percent confidence intervals were calculated as the parameter standard error “ t0.025,n distribution.
‘ Mean separation of the of the individual parameters at each sampling date using a multiple linear regression model in SAS's
general linear model procedure (GLM) (SAS Institute, Cary. N.C.).

109

 

NCO-#01

A
I

 

NCO->010

Shoot dry weight (g)

 

NOD-#010

 

 

 

“111,;

o 2 4 6 81012141618
Weeks from planting

 

A Rockwool <> Coir O Peat1
v Peat2 0 Peat3 U Peat4

 

 

 

Fig. 1. New shoot dry weight of impatiens grown in six root media containing various
rates of hydrated dolomitic lime (Ca(OH)2 and Mg(OH)2) with three nutrient solution
treatments at 4, 8, 12, and 17 weeks after planting in Expt. 1. After each harvest,
remaining plants were pruned to the same point. Data represent only the new shoot
growth from the previous four-week period. Error bars were calculated as 95%
confidence intervals for each nutrient solution. Data are means of four samples at each
date.

110
Acidic NS Neutral NS Basic NS

 

 

Root-zone pH

 

 

 

 

Root-zone Ca2+ (mg-L")

 

 

 

 

 

 

 

 

 

 

 

 

Root-zone Mg” (mg-L")

 

 

 

Weeks from planting

A Rockwool <> Coir o Peat1
v Peat 2 0 Peat 3 1:1 Peat4

 

 

 

 

Fig. 2. Root-zone pH, Ca”, and Mg” concentrations in plants grown in six root media
containing various rates of hydrated dolomitic lime (Ca(OH)2 and Mg(OH)2) with
three nutrient solutions between weeks 1 and 17 in Expt. 1. The dotted lines ( """ )
represent the recommended optimal ranges and dashed lines (----) (if present) represent
the lower recommended acceptable range for the saturated media extract (Warncke and
Krauskopf, 1983). Error bars were calculated as 95% confidence intervals for each
nutrient solution. Overall statistical analysis is presented in Table 3. Data are means of
four samples at each date.

111

Acidic NS Neutral NS Basic NS

 

Root-zone pH

 

 

 

 

Root-zone Ca” (mg-L")

 

 

 

 

 

Root-zone Mg” (mg'L'1)

 

”I

l l l l

 

 

 

 

 

 

 

 

. 1. ‘ I
8 12 16 0 4 8 12 16 0 4
Weeks from Jlanting

Hydrated Lime: 0 Peat1 :1 Peat 4
Carbonate Lime: I Peat1 I Peat4

 

 

 

 

Fig. 3. Root-zone pH, Ca”, and Mg” concentrations in plants grown in two media
containing either hydrated dolomitic lime (Ca(OH)2 and Mg(OH)2) or carbonate
dolomitic lime (CaCO3 and MgCO3) with three nutrient solutions between weeks 1 and
17 in Expt. 2. The dotted lines ( """ ) represent the recommended optimal ranges and
dashed lines (----) (if present) represent the lower recommended acceptable range for
the saturated media extract (Warncke and Krauskopf, 1983). Error bars were calculated
as 95% confidence intervals for each nutrient solution. Overall statistical analysis is
presented in Table 4. Data are means of four samples at each date.

3.0
2.5
2.0

1.5 ‘
1.0 .

0.5
0.0

1.0
0.5
0.0

Shoot-Tissue Ca (dry mass %)

2.5 1
2.0 1
1.5 1
1.0 3
0.5 3

0.0

2.5 «
2.0 3
1.5 3
1.0 1
0.5 3
0.0 l
2.5 i
2.0 3
1.5 :

Calcium

 

1 Week 4
j r2 = 0.48
.1

9

11.1.1

 

1 Week 8

 

1
1
1

4

 

 

Week 17

13:0.96

 

‘2. .1. 1.

 

 

0 40 80 120 160
Solution Ca” (mg-L")

112

 

1 5 Magnesium
' 3 Week 4
1.2 - r2: 0.38

 

 

 

 

 

jWeekB
$3 1.2 112:0.74
3 0.91
(U 1
E 0.6-2
5 0.31
000‘13.....I
5 jWeek 12
g 12:12:079
3 .
._ 0.9 1
'7 :
‘5 0.6 -
g I
a) 0:31
1
0.0-11 E A A I
jWeek 17
1.2 ~r’=0.86
09-: A
0.6%
03-:
0.0 1L5 . I

 

20 40 60 80
Solution Mg” (mg-L")

 

v Peat 2

 

A Rockwool <> Coir 0 Peat1

o Peat3 1:1 Peat4

 

 

Fig. 4. The effect of applied Ca” and Mg” concentration on the shoot-tissue Ca and Mg
of impatiens grown in six root media at 4, 8, 12, and 17 weeks after planting in Expt.
1. The solid line (—) represents the predicted shoot-tissue Ca concentration based on

linear regression analysis. The r2 values were calculated as l-SS

/SScorrected total, and

residual

remaining statistical analyses of the individual parameters are presented in Table 5.
Data are means of four samples at each date.

 

 

 

 

 

 

 

Calcium
25 Week4
' 1
2.03
i o
1.51 . I
1.0« 0
05-1 1
0.0 . + 1 . 4
lWeekB
Q 2.51
"m 2.01
(‘8 1.51%
E 1.0<
2‘
3 0.5
‘5 0.0 1.2.2, ‘1
<3 251Week12
8 '1
E 1.5:
8 1.0< 0
c 1
U) 0.51
0.0 1‘ -" e4 ‘1
25 Week17
2.01
1.53
O
1.0, /
0.5-
0.031. I 1 . 1 .31
0 40 80 120160

Fig. 5. The effect of applied Ca” and Mg” concentration on the shoot—tissue Ca and Mg
of impatiens grown in two root media containing either hydrated dolomitic lime
(Ca(OH)2 and Mg(OH)2) or carbonate dolomitic lime (CaCO3 and MgCO3) at 4, 8, 12,
and 17 weeks afier planting in Expt. 2. The solid line (—) represents the predicted
shoot-tissue Ca concentration based on linear regression analysis from Fig. 4 and

Solution Ca” (mg~L")

113

Shoot-Tissue Mg (dry mass %)

1.5

Magnesium

 

1.2 <

0.9 ‘

D

0.6
0.3
0.0

1 Week 4

11.....1

 

1.2 ~

0.9

0.6 r

0.3 <

0.0

j Week 8

H
'H

L A J

 

1.2 1

0.9 3

0.6 3

0.3 3

0.0

1 1
H

)-

I

jWeek 12

O

I

 

1.2:

0.9 3

0.6 3
0.3 3
0.0 3

j Week

 

17

 

 

Solution Mg” (mg-L")

 

 

Hydrated Lime: 0 Peat1 U
Carbonate Lime: I Peat1 I

Peat 4
Peat 4

 

 

Table 5. Data are means of four samples at each date.

SECTION V

THE EFFECT OF BEDDING PLANT SPECIES ON
ROOT-ZONE pH, CALCIUM, AND MAGNESIUM
MANAGEMENT

Effect of Bedding Plant Species on pH, Calcium, and Magnesium Management in

Peat-Based Root Media

William R. Argol and John A. Biembaum2

Department of Horticulture, Michigan State University, East Lansing, MI 48824-1325

We acknowledge the Michigan Agricultural Experiment Station and the Blackmore
Company for supporting this research. Plant material was provided by Pinter Brothers
Greenhouse, Ypsilanti, Michigan. The use of trade names in this publication does not
imply endorsement of the products named or criticism of similar ones not mentioned.

' Graduate Research Assistant.

2 Associate Professor.

114

1 15
Effect of Bedding Plant Species on pH, Calcium, and Magnesium Management in

Peat-Based Root Media

Additional index words. peat, soilless media, water-soluble fertilizer

Abstract. Nine bedding plant species were grown for 28 days in a peat-based root media
and fertilized with one of three nutrient solutions (NS) composed of three commercially
available water-soluble fertilizers that varied in NH4 : NO3 ratio, Ca, and Mg content
mixed with a single irrigation water source. A NS was applied with every irrigation. In
general, the NS affected the shoot-dry weight of the nine species minimally. Increasing
the NH4 content of the NS decreased medium pH. Plant species also affected medium
pH. In general, medium containing geraniums had the lowest pH while medium
containing petunias had the highest pH given the same NS and averaged over the last 14
days of the experiment. There was a linear increase in shoot-tissue Ca and Mg as the
concentration of Ca in the NS increased from 50 to 96 mg-L"; and that of Mg, from 15 to
38 mg-L". Linear regression analysis of shoot-tissue Ca and Mg based on their

concentration in the NS indicated differences in uptake between species.

116
Media pH must be managed carefully to control nutrient availability in container

root media (Peterson, 1981). A number of sources that include root medium, lime, the
irrigation-water source (IWS), and water-soluble fertilizer (WSF) interact to affect the
nutrient supply in container root media throughout crop production (Argo and
Biernbaum, 1996; 1997). However, not all sources affect medium pH and macronutrient
management simultaneously or with equal intensity under all conditions. For example,
Argo and Biembaum (1996) demonstrated that residual or unreacted lime contained in a
root medium after the initial equilibrium pH was reached greatly increased the pH, Ca,
and Mg buffering capacity given an acidic NS with low concentrations of Ca and Mg.
Residual lime contained in the root medium had no effect on pH, Ca, or Mg management
when irrigated with nutrient solutions (NS) containing basic WSF and high
concentrations of Ca and Mg.

The plant may also affect pH management. With agronomic crops, some species
are less susceptible to lime-induced iron chlorosis because of the plants ability to lower
the rhizosphere pH through root exodation of H and organic acid (citrate, malate) when
grown in calcareous soils (pH > 7.8). In comparison, species that do not lower the
rhizosphere pH are much more susceptible to lime-induced iron chlorosis (Marschner,
1986). Among cultivars of the same species, there may be considerable differences in the
susceptibility of lime-induced iron chlorosis because of differences in the cultivars ability
to lower the rhizosphere pH (F roehilich and F ehr, 1981; Saxena and Sheldrake, 1980)

In F loriculture crops, much less is known of species or cultivar effects on medium
pH and the resulting differences in nutrient uptake. In laboratory experiments on
germinating seedlings, Bailey et al. (1996) found that substrate pH varied from 4.5 with
tomatoes to 7.5 with zinnia under the same conditions. In greenhouse experiments, Argo
et al. (1997) found that the average root-medium pH of ten potted plant species given the

same WSF (20N-4.3P-l6.6K Peatlite Special [Scotts, Marysville, Ohio]) ranged from 5.1

l 17
with African violets to 6.5 with gerbera. In addition, WSF concentration also influenced

root medium pH. For example, the root-medium pH of gerbera decreased from 7.1 to 5.8
as the N concentration of the WSF increased from 50 to 200 mg‘L“, while with African
violets, the root-medium pH also decreased, but from 5.2 to 4.8, given the same WSF
concentrations.

Different plant species are thought to have different rates of nutrient uptake (Bunt,
1988; Dole and Wilkens, 1988). Argo and Biembaum (1996, 1997) found that the uptake
of Ca and Mg into the shoot tissue of impatiens increased linearly as the concentration of
those ions in the NS increased. However, it is not known if the uptake of Ca and Mg into
the shoot tissue of other species is affected only by the NS Ca and Mg concentration. The
objective of this study was to determine differences in pH management and Ca and Mg
uptake in nine bedding plant species.

Materials and Methods

The experiment included 27 treatments composed of three nutrient solutions and
nine species with three replications per treatment. Soil test data were analyzed using
SAS's analysis of variance (ANOVA) procedures (SAS Institute, Cary, NC.) as a 9 x 3
factorial at each sampling date. Time was not included in the ANOVA because sample
variance changed over time. Relationships were developed between the concentration of
Ca and Mg in the applied nutrient solutions and shoot-tissue Ca and Mg using SAS's
linear regression procedure (REG). Slopes and intercepts were compared using SAS’s
general linear model procedure (GLM) for multiple linear regression.

The root medium used was (by volume) 70% Canadian sphagnum peat (F isons
professional black bale peat, Sun Gro Horticulture, Bellevue, Wash.) with long fibers and
little dust (Von Post scale 1-2; Puustjarvi and Robertson, 1975), and 30% perlite. A
dolomitic hydrated lime (Ca(OH)2 and Mg(OH)2) was added at 1.5 kg-m‘3. In addition,
0.4 kg each of KNO3 and gypsum, 0.1 kg triple superphosphate (O N-19.8 P-O K), and

118
0.07 kg fritted trace elements (FTE 555, Scotts, Marysville, Ohio) per m3 of medium

were added at mixing. Sufficient reverse osmosis (R0) purified water was added at
mixing to bring the moisture content of the medium to 40% to 50% of container capacity,
and the medium was allowed to equilibrate for three days before planting. At planting,
the medium had a pH of 5.9; and electrical conductivity (EC) of 1.3 dS-m"; and (in
mg-L") 75 NO3-N, 20 P, 110 K, 105 Ca, 55 Mg, and 60 SO,—S, based on the saturated
media extract (Warncke, 1986).

The three nutrient solutions varied in the NH, : NO3 ratio, P, Ca, and Mg
concentrations, but were applied at a constant N concentration of 100 mg°L". The three
commercially available WSF were 1) acidic WSF with (in % of total mass) 20 N, 4.3 P,
16.6 K, 0 Ca, 0 Mg Peatlite Special, which had an NH, : NO3 ratio of 0.67 and a potential
acidity of 200 kg/ 1000 kg of fertilizer; 2) neutral WSF with 17 N, 2.2 P, 14.1 K, 3 Ca, 1
Mg, which had an NH, : NO3 ratio of 0.25 and a potential acidity of 0 kg/ 1000 kg of
fertilizer; and 3) basic WSF with 13 N, 0.9 P, 10.8 K, 6 Ca, 3 Mg PlugCare Plus, which
had an NH, : NO3 ratio of 0.03 and a potential basicity of 150 kg/ 1000 kg of fertilizer
(Greencare Fertilizers, Chicago, Ill.). The WSF were mixed with a blend of well and R0
water (1:15 by volume) that had a pH of 6.7; an EC of 0.3 dSm"; 50 Ca”, 15 Mg“, 25
Na’, and 10 SO,-S (mg'L"); and a titratable alkalinity to pH 4.5 of 130 mg CaCO3-L".
The total nutrient concentration of the three NS applied at every irrigation is found in
Table l.

The experiment was conducted starting 6 March 1996 at Michigan State
University, East Lansing, in a well-ventilated glass greenhouse sections with constant air
circulation and cement floors. The bedding plant species tested were ‘Orbit Hot Pink’
geraniums (Pelargonium x hortorum), ‘Super Elfin Violet’ impatiens (Impatiens
Wallerna Hook F.), ‘Bonanza Yellow’ marigold (Tagetes patula), ‘Pink’ Nonstop

begonia (Begonia x tuberhybrida), ‘Orange Crown’ pansy (Viola x wittrockiana), ‘Flash

1 19
Rose’ petunia (Petunia x hybrida), ‘Sizzler Lavender’ salvia (Salvia splendens), ‘Little

Bright Eyes’ vinca (Vinca rosea), and ‘Vodka’ wax begonia (Begonia x semperflorens-
cultorum). Plugs from a 512 tray (288 tray for geraniums) were planted into 1204 (0.07 L
per cell) bedding plant flats containing the peat/perlite medium. Plants in each flat were
irrigated as needed with 0.5 L from one of the three NS using a small sprinkling can for
uniform distribution. The volume of solution applied produced minimal leaching.

Root media were sampled initially and collected from one cell per flat (three per
treatment) at 3, 7, 14, 21, and 28 days after planting. Medium pH and EC were tested
using the 1:2 sampling method (Biembaum et al., 1993). Medium pH and EC were
determined by inserting the electrodes directly into the slurry.

Shoot dry weight and tissue nutrient analysis were determined at 35 days after
planting. Eight plants per replication (three replications per treatment) were combined for
shoot-tissue nutrient analysis. Shoot-tissue N was determined colorimetrically, and shoot
P, K, Ca, and Mg were determined by plasma emission spectroscopy (Michigan State
University Plant and Soil Testing Laboratory, East Lansing).

Results and Discussion

Plant growth. The average per plant shoot dry mass ranged from 1.2 g with
geraniums to 0.4 g with Nonstop begonias after five weeks of growth. In general, NS
treatments did not affect either visual appearance (data not shown) or the shoot dry
weight (Table 2) of the nine species. These results are similar to those of Argo and
Biembaum (1996; 1997) in which the ratio of NH, : NO3 contained in the NS affected the
shoot dry weight of impatiens minimally.

Root-medium pH. Between planting and day 7, root-medium pH was similar for
all treatments (Fig. 1). Argo and Biembaum (1996, 1997) found that the NS had minimal
effect on root-medium pH up to four weeks after planting in larger-size containers (0.75

L), which suggests that for a time after planting, the plant and the applied NS have

120
minimal effect on root medium pH. Nutritional problems associated with either low or

high medium pH that occur during this short time period are probably due to an incorrect
lime incorporation rate. The duration of the period when the root medium and lime are
the primary factors affecting medium pH probably is influenced by the ratio of container
size to the plant size and the irrigation frequency.

After day 7, both the nutrient solution and plant species affected root-medium pH
(Fig. 1). Plants grown in media given the acidic NS had the lowest root-medium pH,
while those given the basic NS had the highest medium pH. In general, the media of
geraniums had the lowest pH and geraniums tended to lower the pH independently of the
NS that was applied. In comparison, the other species maintained their medium pH up to
1.4 pH units higher than that of the geraniums given the same NS. For the remaining
species averaged over the NS treatments, the media from the wax begonias had the lowest
pH, while the petunias had the highest pH over the last three weeks of the experiment.

Bailey et al. (1996) suggest that the same WSF should not be used on all species
because of the effect that the reaction produced by the WSF has on medium pH.
However, it may be difficult to use different WSF on bedding plant species being grown
in the same greenhouse. An alternative method for optimizing pH management using the
same WSF may be to use two or more media with different starting pH values. For
example, species that tend to decrease medium pH (geraniums) can be planted into a
medium with a starting pH >6.0. In comparison, species that tend to increase pH
(petunias) can be planted into a medium with a starting pH < 5.8. While plant species
will still affect the medium pH, the amount of change required to produce either toxicity
problems because of low pH (Fe and Mn toxicity in geraniums) or deficiency problems
because of high pH (Fe deficiency in petunias) will be increased.

Shoot-tissue Ca. The higher the Ca concentration in the applied NS, the higher

the tissue Ca (Fig. 2). With each of the nine species, there was an overall linear increase

121
in shoot-tissue Ca as the applied Ca concentrations in the NS increased from 50 to 96

mg-L'l (Fig. 2, Table 3). The intercept value reflects the Ca supplied by the root medium
if no additional Ca were applied in the NS. The slope and intercept values of the nine
species indicate that impatiens were the most efficient at taking up Ca, while Nonstop
begonia, pansies, vinca, and wax begonias were the least efficient given the same NS.

A linear trend with only three treatment levels does not necessarily indicate a
linear relationship. However, a similar linear relationship between the concentration of
Ca in the NS and shoot-tissue Ca of impatiens was reported by Argo and Biembaum
(1996) using 12 different NS that varied by a factor of 10 in the Ca concentration. We
interpret the results of this experiment to add further support to Argo and Biembaum’s
(1996) conclusion that other ions in the NS (NH,, K) did not interfere with Ca uptake.
Instead the main factor affecting uptake in the nine species tested is NS Ca concentration,
as affected by both the WSF and IWS.

Shoot-tissue Mg. As with Ca, the higher the Mg concentration in the applied NS,
the higher the tissue Mg (Fig. 3). With each of the nine species, there was an overall
linear increase in shoot-tissue Mg as the applied Mg concentrations in the NS increased
from 15 to 38 mg-L" (Fig. 3, Table 3). The intercept value reflects the Mg supplied by
the root medium if no additional Mg were applied in the NS. The slope and intercept
values of the nine species indicate that impatiens were the most efficient at taking up Mg
while geraniums, pansies, and vinca, were the least efficient given the same NS.

Conclusion. In the production of container-grown crops, it is no longer acceptable
to manage the pH and macronutrient concentrations in the root medium and plant tissue
with high WSF concentrations and high leaching rates (Biernbaum, 1992). Irrigation
systems that minimize or eliminate water and fertilizer runoff into the environment
currently exist. Optimizing the pH, Ca, and Mg management of low- or nonleaching

irrigation systems requires an understanding of how a variety of factors, including the

122
plant species and the NS, interact during production. Further study is needed to

determine the effect that varieties within a given plant species have on pH and nutrient
management. Quantification of the effects that different-size containers have on pH and
nutrient management is also needed. Finally, it is not known how changing the WSF N
concentration affects root-medium pH, Ca, and Mg management. Future experiments
should be performed with consideration of the interactive effects WSF, irrigation-water
alkalinity, lime, root-medium components, and plant species have on maintaining a stable
root-medium pH and supplying Ca and Mg.
Literature Cited
Argo, W.R., B.J. Weesies, E.M. Bergman, M. Marshal, and J.A. Biembaum. 1997. Evaluation of
rhizon soil solution samplers as a method for nutrient solution extraction and media analysis
for container-grown crops. HortTechnology. (In review).
Argo, W.R. and J.A. Biembaum. 1997. The Effect of Root Media on Root-Zone pH, Calcium,
and Magnesium Management in Containers with Impatiens. J. Amer. Soc. Hort. Sci. (In press).
Argo, W.R. and J.A. Biembaum. 1996. The effect of lime, irrigation-water source, and water-
soluble fertilizer on root-zone pH, EC, and macronutrient management of container root media
with impatiens. J. Amer. Soc. Hort. Sci. 121(3):442-452.
Biernbaum, J.A. M.V. Yelanich, W.R. Argo, D.D. Warncke, and D.M. Krauskopf. 1993. On-site

soil testing training video and workbook. Professional Plant Growers Assoc. Lansing, Mich.

Biernbaum, J.A. 1992. Root-zone management of greenhouse container-grown crops to control
water and fertilizer use. HortTechnology 2(1): 127-132.

Bailey, D.A., P.V. Nelson, and W.C. Fonteno. 1996. Bedding plant fertilization strategies. N.C.
Flower Growers Bul. 41(1):7-14.

Bunt, A.C. 1988. Media and mixes for container-grown plants. Unwin Hyman, London.

Dole, J.M. and HF. Wilkins. 1988. Tissue testing of selected floricultural pot crops. Minnesota
State Flo. Bul. 37(5):l3-15.

Froehlich, D.M. and W.R. Fehr. 1981. Agronomic performance of soybeans with differing levels

of iron deficiency chlorosis on calcareous soil. Crop Sci. 21 :43 8-440.

1 23
Marschner, H. 1986. Mineral nutrition of higher plants. Academic Press, London.

Peterson, J.C. 1981. Modify your pH perspective. Florist's Rev. 169(43 86):34-35, 92-93.

Puustjarvi, V. and R.A. Robertson. 1975. Physical and chemical properties, p. 23-38. In: D.W.
Robinson and J .G.D. Lamb (eds.). Peat in horticulture. Academic Press, London.

Saxenam, N. and AR. Sheldrake. 1980. Iron chlorosis in chickpea (Cicer arietinum L.)grown on
high pH calcareous vertisol. Field Crops Res. 3:211-214.

Warncke, DD. 1986. Analyzing greenhouse growth media by the saturation extraction method.
HortScience 21(2):223-225.

Warncke, D. and D. Krauskopf. 1983. Greenhouse media: Testing and nutrition guidelines.

Michigan State Univ. Ext. Bul. E-l736.

124
Table 1. Total concentrations of the nutrient solution (NS) used in the experiment.

 

 

NH,-N NO3-N PO,-P K Ca Mg Na

(mg'U)
Acidic NS 2 40 60 23 83 50 15 22
Neutral NS ’ 20 8O 13 83 68 21 22
Basic NS " 3 97 7 83 96 38 22

 

‘ 20 N-4.3 P-l6.6 K-O Ca~0 Mg Peatlite Special (Greencare fertilizers, Chicago, 11].) mixed with a blend of reverse osmosis and well
water.

3’ l7 N-2.2 P-l4.l K-3 Ca-l Mg (Greencare fertilizers, Chicago, Ill.) mixed with a blend of reverse osmosis and well water.

‘ l3 N-0.9 P-10.8 K-6 Ca-3 Mg PlugCare Plus (Greencare Fertilizers, Chicago, Ill.) mixed with a blend of reverse osmosis and well
water.

Table 2. Shoot dry weight of nine species grown using three nutrient solutions (NS)
containing different NH, : NO3 ratios, Ca and Mg concentrations. Mean separation across
rows using LSD at P > 0.05. Data are mean of three samples.

 

 

Dry weight (g)
Acidic NS Neutral NS Basic NS
Geranium 0.99 a 1.27 a 1.25 a
Impatiens 0.87 a 0.86 a 0.80 a
Marigold 0.81 a 0.81 a 0.95 a
Nonstop begonia 0.45 a 0.42 a 0.46 a
Pansy 0.85 a 0.97 a 0.85 a
Petunia 1.06a 1.11 a 1.06a
Salvia 1.19 a 0.95 a 1.05 a
Vinca 0.67 a 0.49 ab 0.42 b
Wax begonia 0.53 a 0.74 a 0.65 a

 

125

Table 3. Parameters of linear regression analysis for tissue Ca and Mg, based on the
applied concentration of Ca and Mg in the nutrient solution. Mean separation across
columns of the individual parameters used a multiple linear regression model in
SAS’s general linear model procedure (GLM) (SAS Institute, Cary, N.C.).

 

 

Intercept Slope
(dry mass [%]) (dry mass [%]/mg-L") r2
Shoot-tissue Ca
Geraniums 0.89 i 0.16 ab 0.006 i 0.002 c 0.88
Impatiens 1.03 i- 0.18 a 0.016 t 0.002 a 0.97
Marigold 0.87 i 0.21 ab 0.007 i 0.003 be 0.83
Nonstop begonia 0.49 i 0.25 c 0.008 i 0.003 be 0.83
Pansy 0.40 i 0.23 c 0.008 _+_ 0.003 be 0.84
Petunia 0.72 i 0.29 be 0.010 i 0.004 b 0.83
Salvia 0.90 i 0.20 ab 0.008 i 0.003 bc 0.86
Vinca 0.45 i 0.39 c 0.007 i 0.005 be 0.61
Wax begonia 0.52 i 0.17 c 0.008 i 0.002 be 0.91
Shoot-tissue Mg
Geraniums 0.41 i 0.10 cd 0.006 i 0.004 c 0.63
Impatiens 0.73 i 0.07 a 0.011 i 0.003 bc 0.93
Marigold 0.61 i 0.12 be 0.006 i 0.004 c 0.57
Nonstop begonia 0.64 i 0.10 b 0.006 i 0.004 c 0.69
Pansy 0.44 i 0.07 cd 0.006 i 0.003 c 0.80
Petunia 0.43 i 0.15 cd 0.017 i 0.005 a 0.89
Salvia 0.45 i 0.11 c 0.009 i 0.004 be 0.82
Vinca 0.33 i 0.13 d 0.008 t 0.005 be 0.65
Wax begonia 0.31 i 0.11 d 0.94

0.018 i 0.004 a

 

126

 

l Acidic NS l Neutral NS

Root-medium pH

 

 

 

 

 

 

0 71421280 71421230 7142123
Days from planting

O Geranium Impatiens v Marigold : Non-stop Begonia
I Petunia r3 Pansy O Salvia O Vinca A Wax begonia

Fig. l. Root-medium pH of nine species grown with three nutrient solutions (NS) (Table
1). The dotted lines represent the recommended optimal ranges for the 1:2 testing

method (Warncke and Krauskopf, 1986). Vertical error bars are mean separation using
LSD. Data are mean of three samples.

127

 

3.0
2.5 l

2.0 J

1.5 ‘ M
"/5

1'03 ’9
3
I

 

0.5 t

Shoot-tissue Ca (% dry mass)

 

 

 

40 50 60 70 80 90 100
Applied Ca concentration (mg-L")

O Geraniums O Impatiens v Marigolds
V Non-stop begonia I Pansy El Petunia
O Salvia <> Vinca A Wax begonia

Fig. 2. The effect of applied Ca concentration on the shoot-tissue Ca of nine species at 35
days after planting. The solid line represents the predicted shoot-tissue Ca
concentration based on linear regression analysis. The statistical analysis of the
individual parameters are presented in Table 3. Data are mean of three samples.

128

 

1.4
1.2 r
‘
1.01
Cl v

0.8 r ' I‘VV
- /

0.6 .

0.4 .

Shoot-tissue Mg (% dry mass)

 

 

 

0.2 3 f 1 . 1
10 15 20 25 30 35 4O

Applied Mg concentration (mg-L")

I Geraniums O Impatiens v Marigolds
V Non-stop begonia I Pansy Cl Petunia
O Salvia <> Vinca A Wax begonia

Fig. 3. The effect of applied Mg concentration on the shoot-tissue Mg of nine species at
35 days after planting. The solid line represents the predicted shoot-tissue Mg
concentration based on linear regression analysis. The statistical analysis of the
individual parameters are presented in Table 3. Data are mean of three samples.

Summary

Summary

A number of sources interact to affect the nutrient supply in container root media
throughout crop production. However, these sources do not affect the nutrient supply
simultaneously or with equal intensity. This is especially true for Ca and Mg nutrition,
where the sources can include the irrigation-water source (IWS), root media, lime,
preplant nutrient charge (PNC) fertilizers, and water-soluble fertilizers (WSF). Any
discussion of Ca and Mg nutrition in container root media also must include pH
management because of the direct or indirect effects that Ca and Mg sources have on pH.
Finally, plant growth may directly affect medium pH as well as Ca and Mg uptake. A
better understanding of how these sources interact is necessary to improve the
recommendations for pH, Ca, and Mg management of container-grown crops over a wide
range of conditions using low- or nonleaching irrigation systems. The objective of this
study was to determine which sources are important for pH, Ca, and Mg management,
and how multiple sources that supply Ca and Mg and affect pH interact during production

to affect the overall pH, Ca, and Mg management of a crop.

Root-zone pH management.
Relative importance: Nutrient solution (IWS and WSF) > plant species >

residual lime > root media

The NS, which is composed of the alkalinity concentration in the IWS combined
with the reaction produced by the WSF, was the most important factor influencing pH
management in container grown crops. For example, a similar medium pH was
maintained with a NS combining an acidic WSF (potential acidity of 199 kg/1000 kg)
with 320 mg-L" alkalinity in the IWS or a basic WSF (potential basicity of 175 kg/1000

129

130
kg) with 20 mg-L'l alkalinity in the IWS. Decreasing the concentration of the WSF

lessened effect that the WSF had on the overall reaction produced by the NS.

Plant species also affected medium pH with differences up to 1.4 units given the
same NS. However, the plant effect could be modified by the NS. For example, the pH
of medium containing geraniums was 5.3 with an acidic NS, 5.8 with a neutral NS, and
6.0 with a basic NS, while with petunias, it was 6.1 with an acidic NS, 6.6 with a neutral
NS, and 7.4 with a basic NS after 28 days in production.

Lime that is incorporated into a medium at planting can be divided into two
categories, the first is the lime that reacts with the medium to increase pH to some
equilibrium level and the second is the unreacted or residual lime that remains in the
medium once the equilibrium pH is reached. The equilibrium pH was affected by lime
incorporation, particle size, and the reactivity of the liming material. The presence of
residual lime increased long-term pH buffering in media given an acidic NS containing
low Ca and Mg. For example, media containing residual lime given an acidic NS had a
pH of 5.8, while media containing little residual lime and given the same NS had a pH of
4.5 after seventeen weeks. Reducing the acidity of the NS by reducing the NH,-N
content and increasing the alkalinity concentration in the IWS negated the residual lime
as a source of pH buffering.

Root media had the least influence on pH management. Media containing more
degraded peats slowed the increase in root-medium pH when given neutral or basic NS
compared to media containing less degraded sphagnum peats, coir, or rockwool.
However, there was minimal differences between media type in the decrease of root-
medium pH when given acidic NS. Root medium also influenced lime incorporation rate
which may affect the amount of residual lime remaining in a medium once the

equilibrium pH was reached.

131
Calcium and Mg management.

Relative importance: Nutrient solution (IWS and WSF) > plant species >

residual lime > PNC fertilizers > root media

The Ca and Mg concentration in the NS, which was affected by the Ca and Mg
concentration in both the IWS and WSF, was the most important factor influencing Ca
and Mg management in container grown crops. With impatiens, it was demonstrated that
there was a linear increase in the shoot tissue Ca and Mg concentrations as the
concentration of Ca in the NS increased from 20 to 210 mg-L", and that of Mg, from 7 to
90 mg-L". Other ions contained in the NS (NH,, N03, K, 80,) did not appear to affect Ca
or Mg uptake.

The linear increase in shoot-tissue Ca and Mg was found in eight other bedding
plant species in addition to impatiens. However, there were differences in the shoot-
tissue Ca and Mg concentrations of the nine species. Given the same NS, impatiens were
found to contain the highest shoot-tissue Ca and Mg, while Nonstop begonia, pansies,
vinca, and wax begonias contained the lowest shoot-tissue Ca while geraniums, pansies,
and vinca had the lowest shoot-tissue Mg.

The lime that reacted initially to increase the medium’s pH was found to have a
minimal effect on root-medium Ca or Mg (if dolomitic lime) concentrations. However,
the residual lime did influence long-term Ca and Mg management. Both root-medium
and shoot tissue Ca and Mg concentrations were increased when given an acidic NS
containing low Ca and Mg. Reducing the acidity of the NS by reducing the NH,-N
content and increasing the alkalinity concentration in the IWS negated the residual lime
as a Ca or Mg source.

Preplant nutrient charge fertilizer other than lime (gypsum, triple superphosphate,

Ca(NO3)2, MgSO,) did increase the initial Ca and Mg concentration in the medium.

132
However, the nutrients supplied with the PNC fertilizers were found to be very soluble

and easily removed from the root zone because of leaching or salt stratification within the
pot. With subirrigation, the PNC fertilizers had no effect on root-zone nutrient
concentrations for longer than one week.

Historically, root media has been the primary focus of nutrient management and
buffering in container grown crops. In these experiments, root media had minimal
influence on both short term and long term Ca and Mg management. For example, the
Ca and Mg concentrations in the root medium and shoot tissue of plants grown in a 70%
rockwool/30% perlite medium were similar to those of plants grown in a 70% highly
degraded peat/30% perlite medium. However, root medium did influence lime
incorporation rate which may affect the amount of residual lime remaining in a medium

once the equilibrium pH was reached.

APPENDIX A

GEOGRAPHICAL CHARACTERIZATION OF GREENHOUSE
IRRIGATION WATER FROM THE TEN LEADING STATES IN
FLORICULTURE PRODUCTION

133

 

 

 

 

 

 

 

 

 

 

 

 

35 35
30 CA FL,30
25 -25
2ol -2o
15( ~15
10 I -10
53 II 5
0 ____I ...l-—. -----_.V ‘ . l— o
30 TX MI 30
25 -25
20- -20
153 -15
10 I I ~10
5- I I 5
o l —.I firvq I— ._ -.l' . . 'II _ o
A A
°\o 30l OH} NY.30 °\o
v V
5 25 1 :5 a
1: ml '0 c
g 15 l ‘15 g
g 10 I ‘1 I 10 g
I. 5 . *5 I—
30 PA NJ.30
25 25
201 20
15 >15
10 I] I I I .10
. I I ..
0 u L IJI I Cpl l o
30. NC IL .30
25 L25
20 20
15 15
10 II I II 10
5 I 5
0 ..ll-l “VII—fl. _Il-L-I ‘,,.-l- 0
OVQN‘QQYQN‘QOYQNN QYQN‘QOVQN‘QQV‘PN‘V
VVV‘IOIOCDQCDNNOQQCDO) srvvmmrococonvxaoooacmm
Vééééééwéeéqéé" Véééeééééeéééé"
VVVIDIDCDQ‘DNNwa VVVI‘IDIOKDCDQNNDQD
pHrange

Fig. 1. Characterization of irrigation water pH from the 10 leading states in floricultural
production (United States Department of Agriculture Floriculture Crops 1994
Summary, Washington DC.)

134

 

 

 

30 30

20 20

10 ‘ 1°

60 60
50. CA n.5,,
403 '40
30* [30
201 L20
”‘Jllllllll "°
03 -o
50] TX MI,50
40‘ *40
31_I_II_I.I_ILL
0‘

*0
OH

 

 

 

 

 

 

A A
°\° sol NY,so°\°
v v
40 40
E 30‘ so g
s ‘ 2, s
a: 203 . 8'
2 101 40“,:
"L 0 ~ -0
50, PA NJ,50
403 »4o
303 >30
203 -20
103 >10
03 -fi 3%»0
50 NC IL,50
40 >40
303 »3o
203 >20
103 »1o
0 3 3 3-3- -o
NVQQQNVQQ thmqqrrcqw.
9????‘7'7'7" 'TT"???“.’“?'T
thqqmt" Veteuqth
OOOOv—v-v- QVVIODCDmQ
-1
EC range (dS-m

Fig. 2. Characterization of irrigation water electrical conductivity (EC) (in dS-m") from
the 10 leading states in floricultural production (United States Department of
Agriculture Floriculture Crops 1994 Summary, Washington DC).

.—n
U)

 

CA

W 25

4..”
0000010
LII
.n
I'-
OU’I-A cud—AN
O 0010

 

 

OH NY 25

Frequency (%)
Frequency (%)

25 PA NJ 25

NC

 

 

 

 

A—INN ..A—IN

OUIOUIOUIOUIOUIO
”E :-

OUI-i—IN

OUIO

$8888§88§88 98888883§8

vgttx.ee.rx v-Ttwsa?.r:

'ssssssss issssssss
Alkalinity range (mg CaC03/L)

Fig. 3. Characterization of irrigation water alkalinity concentrations (in mg CaC03/L)
from the 10 leading states in floricultural production (United States Department of
Agriculture Floriculture Crops 1994 Summary, Washington DC).

136

 

 

 

 

 

 

70 70
60 CA FLlBO
50 '50
4O '40
30‘ 30
20‘ 20
10‘ 10
O: 0
sci TX M1150
50‘ L50
401 -40
20%| I I ll {20
1O r10
0‘ *0 A
30‘ 50. OH NY.50 °\o
; 503 ’50 :
g 40 ~40 2
g sol ~30 g
a- 20J ~20 8'
I}: 10l IIIIII ~10 Li."
0‘ .0
60* PA NJ»6o
50 *50
40 L40
30 ’30
20 >20
10 ’10
olLl—I-I—I—I—-—-—-.——L ~0
603 NC IL 160
50w L50
401 No
304 i30
20+ *20
10* 'IIII. l10
0: e. - . - - -0
ssesessssss ssesessesss
292,333,; Wei-332.223“

Calcium range (mg'L'1)

Fig. 4. Characterization of irrigation water calcium concentrations (in mg-L") fi'om the
10 leading states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC).

137

100

 

CA

 

Frequency (%)

60+

 

 

 

 

Magnesium range (mg~L'1)

Fig. 5. Characterization of irrigation water magnesium concentrations (in mg-L") from
the 10 leading states in floricultural production (United States Department of

Agriculture Floriculture Crops 1994 Summary, Washington DC).

>100

FL

 

 

100

 

b
OOOOOOOOOOO OOOOOOOOOO
FNMVMONQO’OO PNMVIDONQQO
VinnnoICIV" VIII-IIIIF
OOOOOOOO'A OOOOOOOO'
FNMV’IDCONQg PNMVIOCDNQS

Frequency (%)

 

138

 

100 100

 

 

 

 

 

 

 

A ’3
o\° o\
v V
5 5‘
c c:
a) a)
3 3-
92 9
u. > u.
so 4 PA "J r so
60 ‘ t 60
4o « 4o
20 + 20
o < . ~ ~ - v . . v 0
so 4 NC IL i 8°
so i » so
40 l r 40
20 < .
O 4

   

'- N 0') V In (D B Q 0 P N 1") V In (D N Q 03 O O
V I I I I I I I I P ‘- V I I I I I I I I ‘- '-
O O C 3 O O O O ' A O O O O O O O o ' A

Sulfate 8 range (mg'L'1)

Fig. 6. Characterization of irrigation water sulfate S concentrations (in mgrL") from the
10 leading states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC).

139

 

70 7O
50 4 CA FL 60
50 50
40 40

Frequency (%)

ngbUI
00° 00
E §{ 3;

r

Frequency (%)

0|
0

N045
OOO

8°888388°388888°838888°888

'20
>10
L0

 

 

 

 

AM“
0000

U

o 8

F

828g“ VESSSSSESé‘
Sodium range (mg-L")

<10
10-20

sessessas assessesses
8 S

Fig. 7. Characterization of irrigation water sodium concentrations (in mg-L") from the 10
leading states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC).

140

 

 

 

 

 

70 70
50, CA FLiso
50* >50
4o< L40
30‘ r30
20* >20
10"..I I I >10
0* *0
60‘ TX MI»60
50‘ r50
404 +40
304 l30
20‘ ~20
10lllll I ’10
A 04 +0 A
°\° 60- OH NY»60 °\°
V v
a 33, ,23 a
c c
a) aoi >30 o
3 20 >20 3-
9 10 r10 9
LI. 0] *0 LI.
60‘ PA NJ»60
50‘ ’50
40‘ ’40
30* r30
20w '20
10* ’10
0 *0
60 NC |L>60
50‘ 150
40‘ >40
30‘ >30
201 ll »20
104 >10
0* *0
sasssssssas sssssasssse
28838828é" 988$8828é"

Chloride range (mg-L4)

Characterization of irrigation water chloride concentrations (in mg'L") from the 10
leading states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC).

141

100

100
CA FL
80* .30

 

 

Frequency (%)
Frequency (%)

 

 

 

 

 

 

<o.2
02-04
04-00
06-08
03-10
>1 .0

Boron range (mg-L")

Fig. 8. Characterization of irrigation water boron concentrations (in mg-L") from the 10

leading states in floricultural production (United States Department of Agriculture
Floriculture Crops 1994 Summary, Washington DC).

H

42

 

 

 

 

 

O

 

40 ‘
30
20
10 *

 

N
C

so so
50‘ CA FLfso
40« L40
30- Lso
zo« ~20
mi ~1o
0 lo
50, TX Ml,50
40‘ ~40
30- ~30
20‘ [20
104 ~10
o- ~o
$3 50< 0” NY~50 §
v v
«2‘ 23‘ :32 s
g zol ~20 g
3 10 ~10 8'
1: ol . , L:
501 PA NJ,
All—“:4-

 

 

 

 

0

Calcium : Magnesium ratio range

Fig. 9. Characterization of irrigation water Ca : Mg ratio from the 10 leading states in
floricultural production (United States Department of Agriculture Floriculture Crops
1994 Summary, Washington DC). Values were calculated independently for each
sample.

143

 

 

100 100
r 80
L 60
» 40
> 20

>80

>40
’20

>80

é?

S
Frequency (%)

-20

Frequency (%)

’80
~60

'7

40
* 20

*80
>60
~40
>20

 

 

 

 

 

SAR range

Fig. 10. Characterization of irrigation water sodium adsorption ratio (SAR) from the 10
leading states in floricultural production (United States Department of Agriculture

Floriculture Crops 1994 Summary, Washington DC). Values were calculated
independently for each sample.

 

APPENDIX B

NUTRIENT COMPOSITION OF
COMMERCIALLY AVAILABLE BLENDED
WATER-SOLUBLE FERTILIZERS USED IN THE
GREENHOUSE INDUSTRY

144

632.2 .32 62.2 .2 8.52:2 .22 82.225 .5 22.222: .22 3.222202 .02 E 3.22... €258.22

 

 

.2288 0.2.6.22 .

8.2 3 ..o 3 ..o .3 - - 2 2 - S 2.. - 8. 8. 2.2.3
8... 3 3 3 ..o .3 - - 2 v - o: a 5 8 a 2-2....
8.2 ..o 3 ..o ..o to - - 2 : - .2 .2 8. R - 2.2-8
2... S ..o ..o ..o no - - .2 2 - a a. .2 2 2: E-..
8.2 ..o ..o ..c ..o no - - _ _ - 8. a 2: an .2 82-8
2.2 3 3 ..o 3 2 - - 2 a - 2.. a - .2 a 8-3.
2.2 ..o S ..o ..o e... - - a : - 3. a - B. a 2-2-:
8 .o 2.: 2.: ..o 2.: ed - - on S - «5 2m - 22 8 3.2.2.2
.2... ..o ..o S ..o 3 - - a 2. - E E 2. a .2 822-2
2... ..o 3 3 3 S - - - a a n: - - 2: o. 22.2
.3 S 3 S S 2 - - a. 2 - 2.. E. - on 3.. 2-212
.2 ..o 8 2 N... 2 - - on 2 - an. a. - E e. as...

nawav .28882
22 2 ..N .6 ..2 02 6 .2 m 22 ..u 2 2 2-85 2-62 2-22

 

..-AWE com .8 22828828 2 :2 8 20.222202 0328-28.23 2292220Nn 32.5% 22828088 80228: :28. .N 032.2.

23:25.
2o 8. 82 202 .0333 2: .0228 .8 an E :92» .2 :22an 05 .8 62:82 05 2:2 as 0:23 20 As 0662 20:20 2 8288 2: 02b 2:. .232an 0.22—8-2823 05 8 8288 388:2 2F .
{8.9. _ 202 z 3.28 82 one: 0m 28 98: 2
.2228 0.2-6.22 .

 

 

62.225 62.22 62.2.22 6me 622 2:. < 2: 2.2 3 - E 22 - 2 2 2.213
8.... 62.2.28 62.2.22 6%: .622 «R < 28 3 no - 2.2 2 ...o. 2 3 2-32
8... 62.22 6222 .622 «8 < 22 5 3 - 2.: v... 2: m... - 237$

s... 626.222 62.22 6.9.»: .622 ..2. < a: 2.2 o: - m.“ ..m 3 2.. n: :22
a... 6.2.2.25 62.22 62.2.22 6%: .622 82 < 28 ..o ..o - no. 2 2: ...n 3 8222
62.22 62.2.22 6.22 .622 8. < 8. 2.. 2o - n: 2 - 2.2 2.2 8.32
6.2625 62.22 62.2.22 .2622: .622 z < .5 M: 3 - 32 ...2 - :2 2.2 2-2-:

.8525 62.22 62.2.22 6me .622 m < 2. 3 3 - 2.8 S - 2.: N.“ 22.1:
8.: 625222 62.2.22 62.: .622 Q < 3 3 no - 2.8 ...w 5 E o... 2.8.:

62.22 .2622: .622 .2625 a... 2 e: - o.~ ...e 2.2 - - 2.2 2 22.2
62.2.22. 82: .2622: 62.22 .622 SN < 2. o: no - 2.2 22 - 3 3 2.2%
626222 62.2.22 .2622: 62.22 .622 a: < 8: 3 we - :2 2.2 - ca 3. 222-2
£3 2.2.2.282 22.22 .222 .0222 m J: 6 2 2 85 2-62 2.22 238...:

. .8882 cm 222 2.225.. 2.8822

 

8022:2202 0328-232? 522880 :8 22888.82 8022:2882 .2 032,—.
GENE, .fiotoz ..EoU 08.222 222229 23:90.2 0528.883 2292220

145

.9232 .32 ”62.2 .2 2.22222 .22 ”2.525 .5 2.2-22:: a: ”8:222 .02 2.. 8222.... 252.2222

.7928 36 3202 22 22828088 2088028 .205 25 20222202 0.8.8-2083 05 5 80208 08 280228: 05 85 08065 2.0 V 2:28-2:083 8022288022

.2268 0.2.6.22 .

 

 

8.2 2.2 no no ...2 2.2 - - 3 m - R 8 8 - 8. E- 8
8.2 No no 2.2 ...o 2.2 - - - - - a: 22 8 S 8 8-88
8.2 2.2 2.2 no to 2.2 - - - - - S. 2... - 82 8 8228
8.2 2.2 no 2 ...c 2.2 - - - - - 28 8 8. 22 2 828
8.2 No no 2.2 ...o 2.2 - - - - 8 a: - 8 o: - 8-?8
8.2 No 2.2 8 ...o 2.2 - - - 2 8 we 8 - 82 8 2-2-:
2 .o 2.2 3 ...o no 2 - - - 8 8 2.2 2 - a: 8 2.2.2
8.2 No 2.2 ...o no 2.. - - - - a .2: 8 2 :2 8 2-2-2
2 .o 2.2 2.2 ...o 2.2 2.2 - - - 2.. 8 .8 8 - 2.2 2 8-32
2 .2 2.2 2.2 ...o 2.2 2.. - - - a. 8 2: 2 - a. 2 2-2-2
2 .o 3 2.2 2.2 2.2 E 28 - - - - E 5. - - 28 2.2%

9-4.35 3:882
82 2 =2 .6 .22 02 6 .2 2 222 8 2 2 2.85 2-62 2.22

 

2.4-WE com .2: 528280820 2 :2 8 20222202 03202-2083 0220:0020 .3 20:69.2 528280800 80228: .282. .2. 032.2.

20222220..

2: 22 82 206 220.222 2: 22202 .2: ma 8 2022 .2 222020.. 05 2: 5220-22 05 2:2 R: 02222 2: 25 02202 20520 22 :020202 2: 09¢ 02... 202.223.. 0228-2083 05 .8 :020202 228082 02:. .

...E.m: _ 202 2 74.28 022 0222 um 28 285 2
8.22:8 0.2-20.2-2 .

 

 

8... 621222 62.2.22 .68: .62 28 < 2: 2.2 no - 2.2 22 2.2 - 2.2 2.2.8
8... 62.2.22 .622 :- < 82 - - - 2.8 2.2 2.2 2.2 2.. 8-28
8... 62.2.22 .622 8 < 28 - - - 2: 2.2 2.2 2.2 2.2 8.88
62.22 62.2.22 .622 .22 < 22 - - - n2: 3. - 2.2 2.2 8.2-8

3... .622 .2625 o < 28 - - 2.2 2.2 - 2.2 o. : - 82.8

62.22 62.2.22 .2628: .622 .2625 o < 22 - 2.. 2..“ 2.: 2.2 - 2.2 .1.- 2-2-:
62.22 .2628: .622 62.22 22622.0 8 2 .22 - 2.2 22 2.: m2 - 32 2.2 2-2-2
62.2.22 .622 .2625 8 < :2 - - 2.2 «.2 2.2 22 2.: 2..“ 2-2-2
.2628: .622 62.22 22622.0 82 2 ..2 - 2.2 o... 2.2 E - 2.2 ...o 8+2
62.2.22 2262222 .622 22622.0 82 2 2.: - 2.2 2.2 2.2 2.2 - 2.2 2.2 2.2.2
62.2.22 .62 E. < 8 - - - ...N. 2.2 - - 2.2 2.9%
2222 80228280222 5w:02m 09C- .0205 m 32 20 v2 m «05 2.2072 2.32 32882

. 883.2 02 2.2.2 2.2.5.. 35522

 

2202:2202 0328-20223 0220:0020 8.2 2022:2082 8022828022 .m 0322.
3: 6220220 2202:2202 0220:0029 2022—2202 0328-2083 0220:0020

146

 

3: 620020 :00 200m 2022st 202.220.. 03208.02...» 0203-8802

...-5......

.0 22 80. .00 5.0.23 ..0 3:20.. ..0 22 5 2032 2 202020. 0... ..0 5220.... 05 0.... E. 0.23 .0 Q. 0.20.. 35.0 2 202000. ..0 0.5 05. 20222.0. 0320.20.03 05 .0 202000. 22.20.00 02... ..
...Efi. _ .00 z .-.—.22. 02. 000.... um .02 ...-2.5 .

......Ee 0.2.02-2 .

 

 

8... :0...2.22 :08: A022 2. < .... .... ..o - m... ...: 28 2 8.8 ...-0.8
8... :0...2.22 :08: ..022 8.. < .2. ..o .... - a... 0.0 28 ...m 0.. 2-2-8
8... :0...2.22 :08: ..022 8. < 80 ..o .... - m... .... 0.8 E .... ...-2-8
8... 62.222 :08: ..022 .8 < 22 ..o .... - n2 «.8 ...: 0.0 8.. 8-28
8... ..022 .8 < 0mm .... .... - 28 - ...: ... - 8.28
8... :02022. ..02.22 :0...2:22 :08: ..022 28 < 88 .... .... - ~.2 2m 3 0... 3 2-2-8
8... 60.022. :0...2:22 :08: ..02 08 < 8. 0.0. .... - .... ....- o8. - .... 5-8
8... :0...2.22 .022 :08: ..022 2.. < ..8 ..o ..o - .... ..m a. . 3 0.. .-.--8
8... :0...2.22 :08: ..022 «8 < 08 ..o ..0 - 22 S. a... N... ...m 88.8
8... 32.222 :08: ..022 8. < 08 N... N... - a... m... .... an 2... 2-2-8
8... :0...2.22 :08: ..022 8. < 28 N... N... - 28 0.0 ...a .... .8 8-2-8
.0222 :0...2.2z :08: ..022 28 < N2 ..0 ..o - 22 .... - 0.2 0.2 8-0.8
8... :0...2:2z :08: ..022 R < 88 ..o ..o - 2.8 8.8 2.. w... 0.. 8-28
8... 30222. :0...2.2z :08: ..022 2.. < .2 o... 0.. - 22 a... ... an ... 888
.0222 ..022 ....0206 8 < S. - - 0.0 22 - - 0.2 0.. 8-?8
.0222 :0...2.22 .022 :08: ..022 8 m .... ..o ..o - a... ... - 0.... ..N 2-1..
8... :0...2.22 :08: ..022 22 < .2 ..o ..o - «.2 ..2 w... m... ...m 2.82
8... :0...2.22 :08: ..022 2... < S. ..o ..o - 28 S. o... 0.. 0... 8-8-2
.0222 :0...2:22 ..02.2 :08: ..022 2. < .... N... ..o - 0.... 0.. - 2.. n... 2-2-2
8... :0...2:22 ..02.2 :08: ..022 .2 < 02 .... .... - ...N. 0.0 m... S 0.. 2-2-2
8... :0...2.22 :08: ..022 2. < S. 8.0 .... - 0.8 2... m... 0... N8 8-. .-2
8... :0...2:22 :08: ..022 8 < m... ..o ..o - 2.8 .... 3 ..a N8 8-0.2
8... :0...2.22 :08: ..022 8 < .... ... n. - 28 8.8 - ...... N... 8-22
8... ..022 ....02...0 0.8 2 n2 - - o... ...N. - 0.8 0.2 - 2.?2
N..022: ..022 2.0280 28 0 0.. - a8 a.“ 8.0. - - ...2 8.. .20....
52.222 ....028: ..022 2.0280 8. 2 S. - o.“ o... no. a... - 2.2 0... 2-8-2
8... :0...2.22 :08: ..022 o... < .... ..o .... - 0. .. E. ... .... 2.0 ...-8-2
.022 .8 m .0. .... ..o - 22 - - o8. - 21.8.
62.222 :08: ..022 :0...22 28 < ..o. w... 0... - n2 ..2 - E .... 8-8-...
52.2.22 ..02 8.. < 8 ..o .... - .8. 3. - - o... 2.21..
.....m auras-.8: .88.... 25 .222 m J: ..0 2 .. 8.2 2.02 2.22 205.02
. 8.882 02 .2. 22.8... .388...

 

2.02520. 0.02—08.0.03 8.0—0.0.002 :0 20208.02: 2.0252882 .m 030,—-
:= 620030 :00 000m 222w=2>v 202—220.. 03200-2083 020320.022

 

.6332 .32 ”6%: .m ”5.35 5N ”585 .5 ”Emma: a: ”ESE a". 3 8:33 9832832
...AEE nod 323 .94 8:228:00 van—=28 :05 :5 33:5 0328-533 05 5 530a 2a 85:5: 05 35 83%.: ed v 23.5588 2.052.922

.2258 oflguofiz N

 

147

 

5d —d dd dd dd Md . u - - - mm aN m0~ ~N 3 d—udeM
ddd Nd nd nd nd dd - - _ _ .. Mb av dn— wN NN NTWTFN
_d.d dd dd dd dd wd . u d m .. 00 MM n9 _N 3 deTWN
_d.d _.d dd dd dd vd . - _ ~ . NM_ N; MV— w? d dNumunN
~dd _.d dd dd dd vd . - ~ ~ - mo~ - Nvd mm . WNudnmN
~dd dd Nd Nd Nd vd .. u _ — u 0: ON do dw dd OTMéN
~dd dd dd dd dd VA on . Nw _ . mm oN v: - cw hubumN
_d.d _.d dd dd dd d4 - wh d m .. mm 0N M: :. E «HFAN
_d.d ~d dd dd dd nd - u _ _ . mo~ hm do Nd OM dNudNudN
d_.d Nd Nd ~d dd d.~ - u N N .. d3 Mm :_ Nn wM wTdeN
d— .d Nd Nd dd ed d._ - - N N - th 00 Va wk. wN MNun—ndN
d~ .d Nd Nd —.d 0.0 d4 fl d _ _ u no— 3. . dN_ dw dNudeN
~dd _.d dd dd dd nd - - _ _ - MVN NN Nd_ mm d_ dMunudN
~dd — d dd dd dd wd - - dw d— - ne— o _h on :. dN-N..dN
d— .d Nd Nd ~.d dd d._ - - u - 8 mo— - - dw— dm dN-dudN
~dd ~d dd ~d dd hd - mm— _ _ . ¢N_ NN - v: 0N N776—
_dd ~d dd ~d dd Nd - u ~ ~ - mg m: 3 an 55 m—dM-n~
_dd ~d dd ~d dd Nd - - ~ ~ - whN :_ Mm Mo Mm WN-dN-w~
d_ d Md Nd ~d nd d._ - do N N . 52 MG - Q: 00 5.707%—
_d.d _d dd dd dd 5.0 - do _ _ . m©~ NM 3 ca QM anTn—
cm .0 Md Nd _.d dd d._ - - N N . ddM V0 hm v: ON dNu:-n~
~dd _.d dd _.d dd bd .. - d m - dMM mm av NN~ oN deT2
dd; ~d 5.0 _.d ed d4 - - MN m~ . mwN dN - 3; on WN..m-m~
~dd _ d dd _ d dd 5.0 - - - u 3; m2 - hN M: - 2-0.2
_d.d _.d Md Md Md wd - n u _v vw mv— - .. vw~ ©~ V—.d..¢~
_d.d ad Md Md Md wd - u - mv do _0_ Md . _o_ a MTNuM~
Ndd dd dd _.d ~d wd - - d _ . M0— NON a we M: .v—-©M-N—
Ndd _.d dd ~d ~ d wd . - ~ ~ - Nan . - ddN . MvnduN~
Ndd _d _.d _.d ~d d4 - - o~ Nd - dMM NoN - M: hm dNudM-d_
Ndd Nd ~d dd dd ~.~ dMN - _ fl . WBN th - . ddN MTWYG

paws; “Bantam
O2 m GN DU :2 on _0 «Z w ME «0 v— n— 2&8: ZkOZ ZRIZ

 

4-4%.: com ho :ocabcoocoo 2 cm 8 B~=E£ 03283533 way—£232 3 8:553 :otmbcoocg Eats: .88. .c 035.

148

32:23

.8 mg. 82 .28 £223 S 2:28 3 mu S :03» 2 8282 05 3 59.38 05 can Rd 223 .8 A5 0:28 .553 2 .5282 .3 25 25. 32:28 0328-2385 on. 3 5.288 32:38 25. .
...e.% 2 .22 2 .285 0: 3% um .8 2:5 .

ass-é 06-662 _

 

 

8:. ..8662 .682 .622 8.2 < v: S S - 3 3 S8 2 28 2-2-8
83 ..2662 .682 .622 at. < 82. 3 S - ad 3 «:8 28 3 2-2-8
83 .6262 ..2662 .682 .622 o8 < ”8 3 g - v.2 N8 3. 2.: 3 2-28
8.5 .682 .622 88 < 88 3 3 - 28 - Q2 2 - 8.3.8
no... 622622 .6262 ..2662 .6me .622 28 < 88 3 3 - «.2 on 3 ed 3 2-8-8
8:. ..82622 ..8662 .682 .62 92. < 82 92 3 - an 3 92 - 2 5-8
85 ..2662 .622 .6me .622 2: < 88 3 _.o - 3 2.8 Q2 5 3 5-8
85 ..2662 .682 .622 «2. < 88 S 3 - 3 2.2 m. : 3. 3 28.8
8:. ..2662 .682 .622 88 < o8 S _.o - 22 E «.2 on 3 8-8-8
8:. ..2662 .682 .622 8 < o8 do No - 32 3 2.: «a 3” 2-2-8
6262 ..2662 .682 .622 :N < N2 3 No - 22 3. - 92 32 8.28
85 62662 62.2 .682 .622 R < 88 3 2o - ”.8 8.8 8.2 3 3 8-28
85 62265 ..2662 .6me .622 v:- < .2 3 ..o - 22 .3 E 3 2- 8-8-8
6262 ..2662 62.2 .682 .622 S < m: do do - 22 to - 8.: 3 8-2-8
83 .622 66220 o < 88 - - 3 22 - 3 o.: - 858
85 6.2662 .622 .682 .622 8 < 2.. _.o 3 - 3 2 ed 32 2 2+2
6262 ..2662 .682 .622 8 < 22 3 3 - 22 22 we 3. 3 28-2
6262 62662 .682 .622 a: < E 3 S - 28 Z 3. 3 3. 8-8-2
6262 ..2662 .682 .622 «8 < “2 2 MS - 32 3 - 2 3 2-2-2
85 ..2662 .622 .682 .622 22 < 22 No 2.0 - 32 3 M8 2; 3 22-2
85 ..2662 .622 .682 .622 :2 < 02 S 3 - v.2 3 3. N.» 3 2-2-2
8:. ..8662 .682 .622 3 < 2.2 do 3 - Q8 3 3 32 28 8-2 2-2
8; ..8662 .6me .622 8 < m: 3 3 - ”.8 3 2 3 3 82-2
6262 ..8662 .6me .622 8 < 82 E 2 - 28 N8 - 2: 3 8-22
85 .622 66289 SN 2 n2 - - o.: «.2 - - o2 o8 2.?2
8:. ..2662 .682 .622 o8 < a 3 S - 0.: 22 2 2. 3 2-8-2
682 .622 88 m 2: 3 _.o - n8 - - 92 - 2&2
.2662 .6me .6262 .622 2N < 32 we we - 22 22 - 2n 3. 88-2
62662 .6me .62 N2. < 8 3 3 - «.2 22 - - ca 2.2&
.8662 .6me .6262 .62 08 < 8 3 3 - 0.3 $8 - - ca 288
6me .622 .6262 8 m R 3. 2.8 - n8 3. - 9n - 8.2.8
2.8 25:22:8an Emcobm 09C. hMao—m m mi «0 M m 85 2-802 22:2 "Es—Eon
. .5832 um 2.2 2322 3552-2

 

882228 0328-883 8228035 8202 so 2288-285 2:222:8an .h 038-
.830 6532-82 .8809 32:20.2 0338-883 38$

 

.328 36 323 2 202222328 2922qu 206 25 202—228 2228-2823 22 E .2882 22 222-222 05 225 8865 ed v 2222222828 222222822
.2282 022-622 -

 

149

 

8.2 _.o 2.2 2.2 8.2 no - - N 2 - 8 8 n2 8 2 22-8
8.2 8.2 3 2o 22 2.2 - - 2 2 - 8 8 22 8 8 2-2-8
22.2 8.2 he 3 22 3 - - 8 2 - 8 2 8 8 8 2-28
8.2 2.2 2.2 2.2 8.2 to - - 2 2 - - 22 22 8 - 8-28
5.2 2.2 8.2 2.2 8.2 to - - 2 2 - o: 8 8 8 8 2-28
8.2 2.2 2.2 2.2 8.2 o._ 8 - 8 2 - 8 8 :2 8 2 2-2-8
5.2 2.2 2.2 2.2 8.2 I - 8 2 2 - 8 8 2.: - 8 22-8
5.2 3 2.2 2.2 no no - - 2 2 - 8 22 22 8 8 2.88
5.2 2.2 2.2 2.2 no no - - 2 2 - n2 8 2 8 8 8-8.8
2.2 8.2 8.2 3 2o 3 - - m 8 - 2: 8 :2 8 8 22-8
2.2 8.2 8.2 3 2c 3 - - 2 2 - n2 3 - 22 8 828
8.2 2.2 22 22 2o 3. - - 2. m - 5 8 2 2 _ 8 8-88
8.2 3 2.2 2.2 3 no - - 2 2 - 28 8 N2 8 2 8-28
8.2 8.2 8.2 8.2 8.2 no - - 8 2 - n2 2 K 8 8 8-8-8
2 .2 8.2 2.2 2.2 22 3 - 2. m 2 - n2 2. - 2: 8 8-28
2.2 2.2 8.2 3 2o 3 - - - - 8 n2 - 8 22 - 828
8.2 2.2 2.2 3 3 22 - 22 _ _ - v2 8 8 82 2 2-22
5.2 ..o 2.2 2.2 2.2 3 - - 2 _ - m2 m2 8 8 R 2.8-2
2 .o ..o 2.2 2.2 8.2 2.2 - - 2 2 - 88 22 8 8 8 8.8.2
2.2 8.2 8.2 2.2 22 3 - - 2 : - 2: 8 - N: 8 2-2-2
2 .o 8.2 8.2 2.2 22 3 - 8 m 8 - 2: 8 8 2: 2. 2-2-2
8.2 2.2 2.2 3 no 3 - 8 2 2 - m2 2 8 8 8 2.2.2
2.2 8.2 8.2 2.2 22 3 - - N N - 28 8 R 32 8 8.2.2
5.2 2.2 2.2 2.2 no ho - - 2 _ - 28 8 8 82 8 82-2
8.2 3 2.2 2.2 2o 3 - - 8 2 - 88 8 - $2 8 8-22
5.0 2.2 od 2.2 no 3 - - - - 2; m2 - 8 m2 - 222
8.2 3 2.2 3 28 2.2 - - 2 2 - 82 N8 2 8 22 28-2
8.2 S 2.2 S to 2.2 - - 2 2 - N8 - - o8 - 2122
No.2 2.2 2.2 2.2 no 3 - - 2 2 - 28 N8 - m: 8 882
8.2 8.2 2.2 3 22 I 28 - m .2 - 88 E. - - 28 2.2%
3.2 3 2.2 2.2 3 2.8 8 - m N - N8 :2 - - 28 28-2
8.0 28 22 2o 28 2.2 - - 82 2.2 - 28 82 - o8 - 8-2-n

nw—JEV NEaton
22 2 .8 5 22 02 6 22 m 22 .6 2 2 2-85 2-62 2-62

 

._--_.w2 8m .22 202222828 2 22 22. 202—228 2228-2223 22228205 82.-.5 .3 2022222 202222828 222.222 220,—- .2 032-2
.330 6:33.82 .2289 82:28 0328-2823 82280-2022 2.58."—

150

..oozaz 5: ”62.2 .m 2.583 ...N ”555 .5 ”SEN-22 ...: ”Sc-com an. E 8:83 2032.822
.2252 022-6222 .

 

 

2 .o 3 ho S no 3 - - - - - E 3 M: cs S 8.93
86 3 3 ..o no 3 - - - R S a: 8 R E 2 2-92
23 3 no 3 2o 2 - - - R 8 SN 2 : a: on 83-2
85 No no 3 no o2 - - - - ca - - - n: 2 35
2 .o No 9o 3 no 2 - - - - - ma. 3 on o: - 33-:
2 .o no we 3 3 2 - - - o2 - - - - 8N - 992

2.2.25 .2258
o: m ..N 5 :2 on 6 «z m m: 6 2 A. 2-35 2-62 2-52

 

.LME com no 2235588 2 .3 3 Bum—Ea 0328-333 385 «,3qu Na 8:695 2235:0280 235:: .33. .2 223...

...-.235

we ma coo— hog .0633 8 5:23 mo 9. 5 53m fl cocoa“: 05 ho Ewan?- ufi .23 av 23a 5 A5 323 555 2 5:32 mo 25 of. .3255..— o_n:_om-._333 05 .8 .8238 3:282— 05. n

45% 2 .a 2 baa 2“ ac; om .8 3:5 .
22:8 0.2-62.2 .

 

 

3228238: .6me .622 2: < N: - - - “.2 3 3 ed 3 own-3
32.28% 83 62.22 .262va .622 .2625 K m as - o.~ ow «.2 3 Z 3.: 3 2-92
2238.3 83 62.22 .262va .622 .2625 E m E - 03 3 02 20 2o 62 3 own-2
2625 E m n: - - 3: - - - 9: 2: 32
322.8% 8:. .622 5 m NS - - - e. a Na 3 0.: - 33-:
262va m: m E - ca - - - - o2: - ii:
2% 2032.88: 52.2% 09¢ .255 m w: 6 M .2 85 2-62 2.62 32:52
. 8882 um 2.26 292.52 35522

 

Eonatfi 03203833 .ooxm £802 no 22238285 3023:0532 .o 232.
.820 655.032 .300@ SEE-nu 0528-533 382m Eur-i

151

.6812 .22 60.2 .0 3.525 .5 ”2.525 .5 2.52:2 a2 ”ca-:02 .2 B 3:23 3852822
.32.: 86 32B 2 5232:0800 5033030 .205 25 002222 0328-0033 05 2 308:: 0.3 2:222: 05 35 03052 moo-o V 8232:0800 32.—3:822
23.52 02-6222 .

 

 

Odd ~d ed vd vd bd - - - - - Mb 3. #2 an ON 3-3-MN
ddd Nd .vd vd vd wd - - - ~ - ha am MN~ 8 MM 2-x-.vm
5d Nd Md nd md d._ - - - - - me am av ON _M~ 5-6-"N
~dd Nd md md Md 0." - - u - - mm: hm Md— an 6M dN-deN
2 d Nd Md nd md 0.2 - - - _ - m2 30 - dN— ow ONudeN
_dd Nd md nd nd 0; - u - - - wvm NN Nd— ww o_ dMM-ON
2 d Nd md nd nd d4 - u -. ~ - mg a . dfi ow dN-NdN
~dd Md hd hd hd MA - - - - - mg m: Me an 2. MTOM-M~
_dd Md hd bd hd MA - u - - - dMM hm Me. n: QM dMM—-3
de Md Nd hd hd MA -. - - N - we hm av a: ow anTn—
~Nd Md hd hd hd VA .. - - :0 vw m3 .. - v2 2 #7042
god vd d4 d4 04 d.N - - - u . m2 9% 6N E 02 dTNmA:

27.2-$5 N3.52.52
02 m 2N :0 :2 on _U :2 m 3.4 «U M m 2.823 Z-~OZ 2-0%—Z

 

..--HMS com .8 22325050 2 :3 3 2022202 0328-0033 x0322 .3 :0zmgm :23220050 2:222: .58. .NH 0232-

202222

.6 as 89 00: .2225 0: .223 ..o mu. 2 :02» 2 :2038 05 .8 52:00:- 05 23 22V 223 3 $2 02203 005.0 2 :22300 .3 02b 0;..- .002228 0328-0033 05 2. :200300 32:88 0.:- .
2.5-m: 2 :0: z 142.: 03 0220 um 08 02:: a

.2258 022-622 N

 

 

85 6222.22 .622 o? < Rm - - - N2: 3 N3 3. 03 2.2.00

85 622.22 £8me .622 5 < 02 - 3 - 0.: 2m 3: 3. n... 2-0-E

8:. 622220 2222.22 .622 E < «2 - - - 3 2m 3 2 .N 0.2 2.2--3
35 6222.22 .622 m2 < 08 - - - 22 2 2: 2n 3 8-8-om
62.22 6222.22 .522»: .622 22 < m: - 2o - m2 3. - 0.2 0.0 82:22
85 622.22 .622 8 < 80 - - - 0.3 2 0.2 0.0 3 0.0--22
62.22 6:22.22 .5:me .622 «2 < 22 - 3 - 22 2o - 0.2 0.0 8-22
as 62.22 6:22.22 .6022 .622 03 < a: - - - «.2 :2 E. I. a.“ 22.2
85 62.22 622.22 .622 9. < 22 - - - 0.3 0.2 2 0.0 .3 8-2-2
8.: 6222.22 222me .622 3 < m: - ~20 - 3: 0.0 E 3 3“ 2-2-2
62.22 .2622: .622 26206 22 m 0: - 3 2m «.2 - - 22 a: 2-9:
8:. ..2222 .6222 .622 o: < 2: - - - 3 EN 3 20 0.5 2.3.2
.28 2052.28: 52.22 22:. 22m 0 m2 6 2 2 85 2-62 2.22 .2582

. 858: um 20 22.22 38822

 

202222 0528-2033 20322 282 :23:222 3253232 .2 053:.
223230 .2380 6222302 :0:— 68:32: 002220.“ 03282033 200522

152

..oozaz .02 202.2 .2 020.0202 .5 ”5025 .5 5.02:2 2: ”2.5002 .00 2. 002003 08202508:
..--H.220 36 3202 2 20222200200 5002—20—20 .205 25 0025008 03200-00023 05 5 2000000 000 2202.22 05 025 0020205 36 V 20000200200200 0202002000022
.2252 0.00-.022 .

 

 

2 .o 0.0 no «.0 2 0.0 - - : 0 - 80 8 8 2 on 2.0.8
2 .o 8.0 3 8.0 3 0.0 - - - - E E - 02 30 - 82:8
8.0 0.0 0.0 0.0 0.0 0.0 - - 2 - - 22 a 20 8 2 8.2.8
2.0 8.0 3 8.0 no 0.0 - - 2 - - a: 8 3 mm 2. 2-28
2 .o 2.0 20 8.0 no 0.0 - - 2 - - 2: 0m - 20 20 8.2.8
8.0 0.0 0.0 2.0 0.0 0.0 - - 0m .2 - m8 8 - 22 S 8-2:
2.0 3 3 8.0 3 0.0 - - 2 : - 0: 8 - :0 2 2-2-2
2 .0 8.0 20 8.0 0.0 0.0 - - - 2 80 n2 - - m2 2 2.22

9-42.5 N2.220002
0: 2 :2 :0 =2 02 .0 “z m 22 6 2 0 2-8.5 2002 2.22

 

.0228 com 00 202200200200 2 20 02 2002:2000 05202-00003 00m_2200._. .3 5022022 202200200200 0202020 :20..- .3 032.2.

00250000
.00 20. 89 000 2207-3 00 200200 00 22 5 000:» 2 2020000 05 .00 5220002 05 222 Amy 22B 00 A<v 0:200 0056 2 2020000 00 0020 02-h 002—00000 03200-00023 05 00 2020200 3200.00 05. .
..-—00.90 _ 000 2 74.220 000 0007- Um 00-0 225 2
.2282 0.2-“0.0-2 .

 

 

30: .6242 ..02222 .6222 .2022 08 < 0.8 S 0.0 - 0.2 3 8.0 0.2 2.0 2.0.8
8.5 30200 2.0206 2 < 08 - - 0 n2 - 0.2 0.00 - 8.0-8

3:. ..023220 30.222 2022 am < 28 0.0 - - n2 3 0.0 0.0 8.0 8.2.8
80: ..0m§2zv 302.22 3022 22 < 28 0... - - 2.: 2.0 2 2n 2... 2-2.8
622.220 202.22 ..02222 2022 28 < :2 0: - - n2 3 - 0.: 3 8-28
n02.22 52.222 .6222 ..022 2. < 82 0.8 0.8 - 2.2 8.8 - 0.: 2 8-2:
20222 30.222 .6222 2022 08 < 22 2 0.0 - 0.: 3 - 0.2 0.0 2-2-2
6222 2.0202: 2022 2.0206 08 2 m2 - 0.0 20 0.2 - - 2.2 2 2-22
2202 022002200022 52.0006 09C. 00205 m m2 «U x m 005 2.0002 2.52 N2.22000"—

. 80082 02 8.0 2222 28522

I‘

 

2002:0000 05200-00023 00220200..- 20000 2022000022 0000202000002 .2 0300-
.622“? .0E>0=0m 0022202032 000 002$ 0020:0000 03202-00023 00220200,.-

"Wflflifi‘flflwMW