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This is to certify that the

thesis entitled

TURFGRASS RESPONSE TO
FERTILIZATION AND CULTIVATION
USING HIGH PRESSURE WATER INJECTION

presented by

Christopher M Miller

has been accepted towards fulfillment
of the requirements for

M.S. Crop & Soil Science

 

 

degree in

 

Major pro essor

4/6/94

 

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

 

 

 

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Michigan State
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”3-9.1

TURFGRASS RESPONSE TO
FERTILIZATION AND CULTIVATION
USING HIGH PRESSURE WATER INJECTION

By

Christopher Michael Miller

A THESIS

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

MASTER OF SCIENCE

Department of Crop and Soil Sciences

1994

ABSTRACT
TURFGRASS RESPONSE To
FERTILIZATION AND CULTIVATION
USING HIGH PRESSURE WATER INJECTION
By

Christopher Michael Miller

High pressure water injection has been developed as a method of soil cultivation
which imparts minimal disruption to a turf surface. Water injection cultivation has
beneficial effects on soil physical properties such as lowering bulk density, increasing
porosity, and improving water conductivity. Studies were conducted to determine the
effectiveness of water injection (W1C) as a method of applying fertilizers and wetting
agents, as compared to traditional surface application of these materials. In addition, the
effect of W1C on surface hardness was examined. Applications of fertilizers using W1C
had no effect on turf quality compared to surface applications. Deeper placement of both P
and K in the soil profile was seen from injection compared to surface application. Both
injection and surface application of wetting agents were equally effective in preventing
formation of localized dry spot on a sand—based putting green, especially at a high rate of
application. Water injection cultivation applied as frequently as every two weeks on 2
separate high traffic sites had no effects on turf quality. Surface hardness, measured using
the Clegg soil impact tester, decreased immediately following application of W1C. Due to
recompaction and settling of the soil from constant traffic, duration of this effect on most

occasions did not last longer than a two week period.

To My Parents

Robert and Frances

iii

ACKNOWLEDGMENTS

I would like to thank and extend my deepest gratitude to Dr. P.E. Rieke, chairman
of my graduate committee, for giving me invaluable guidance and support throughout my
program. His kindness and unending willingness to share his knowledge and valuable
time will neverbe forgotten. I am grateful to Dr. J.M. Vargas and Dr. IN. Rogers 111 for
participating as members of my graduate committee. I would also like to thank Mark Krick
for his valuable friendship, and Jim Murphy and all the other people who have helped me
and made my education a rewarding experience.

Lastly, I would like to thank the Toro Company of Minneapolis, Minnesota for the
financial support of this research project. The interaction with Mr. D. Lonn, Mr. D.
Scherbring, Mr. M. Hoffman, and Dr. J.R. Watson took my experience at Michigan State
beyond that of a typical academic program.

iv

TABLE OF CONTENTS

Page
List of Tables ................................................................................ vi
List of Figures ............................................................................... viii
Chapter One: Fertilization of Turf grass Using High Pressure Water
Injection .................................................................... 1
Abstract .............................................................................. 1
Introduction ......................................................................... 2
Materials and Methods ............................................................. 4
Results and Discussion ............................................................ 9
Phosphorus ................................................................ 9
Potassium .................................................................. 20
Nitrogen .................................................................... 26
List of References .................................................................. 33
Chapter Two: High Pressure Injection of Wetting Agents in Sand-Based
Greens ...................................................................... 35 '
Abstract .............................................................................. 35
Introduction ......................................................................... 36
Materials and Methods ............................................................. 38
Results and Discussion ............................................................ 39
List of References .................................................................. 46
Chapter Three1Water' Injection Cultivation Effects on Surface Hardness and
Tufgrass Quality .......................................................... 47
Abstract ............................................................................. 47
Introduction ........................................................................ 48
Materials and Methods ............................................................ 50
Results and Discussion ........................................................... 53
Forest Akers Site ......................................................... 53
Beal Gardens Site ........................................................ 60
List of References ................................................................. 78
Appendix .................................................................................... 80
Table A - Available soil phosphorus (Olsen) levels at the thatch, O to 7.5,
7.5 to 15.0, and 15.0 to 22.5 cm soil levels, 1990-1993 ........... 81
Table B - Ammonium acetate extractable potassium levels at the
0 to 7.5, 7.5 to 15.0, and 15.0 to 22.5 cm soil levels,
1990- 1993 ................................................................ 82

LIST OF TABLES

Table Page
1.1 Color ratings of a creeping bentgrass green as affected by

phosphorus applications .................................................. 16
1.2 Clipping yields of a creeping bentgrass green as affected

by phosphorus applications .............................................. 18
1.3 Root weight density data from a creeping bentgrass stand ........... 19
1.4 Phosphorus content of creeping bentgrass clippings .................. 21
1.5 Potassium content of annual bluegrass clippings ...................... 27
1.6 Color ratings of a creeping bentgrass green as affected by

nitrogen applications ...................................................... 28
1.7 Clipping yields from a creeping bentgrass green as affected by

nitrogen applications ...................................................... 30
1.8 Total nitrogen content in clippings from a creeping bentgrass

green ........................................................................ 31
2.1 Quality ratings of a creeping bentgrass green as affected by

wetting agent applications ................................................ 40
2.2 Gravimetric soil moisture of a modified loamy sand soil as

affected by wetting agent applications .................................. 42
2.3 Water drop infiltration times, in seconds, from soil cores taken

from a modified loamy sand putting green, 24 Aug., 1993 ........... 43
3.1 Turf grass quality ratings of creeping bentgrass / annual bluegrass

putting green. Forest Akers East Golf Course. 1992 .................. 54
3.2 Turf grass quality ratings of creeping bentgrass / annual bluegrass

putting green. Forest Akers East Golf Course. 1993 .................
3.3 Surface hardness readings (Clegg - 2.25 kg hammer). Forest

Akers East Golf Course practice green. Loamy Sand Soil.

1 992 ......................................................................... 56

vi

3.4

3.5

3.6
3.7
3.8

3.9

3.10

3.11

3.12

3.13

ndix

Surface hardness readings (Clegg — 2.25 kg hammer). Forest
Akers East Golf Course practice green. Loamy Sand Soil.

1993 ......................................................................... 57
Stimpmeter readings before and after water injection treatment.

Forest Akers East Course practice green. 1993 ....................... 61
Turfgrass quality ratings Beal Gardens. 1992 ......................... 62
Turf grass quality ratings Beal Gardens. 1993 ......................... 63

Depth of injection holes following Hydroject treatment. Beal
Gardens. 1992 ............................................................. 64

Depth of injection holes following Hydroject treatment. Beal
Gardens. 1993 ............................................................. 65

Surface hardness readings (Clegg — 2.25 kg hammer). Beal
Gardens. Sandy Loam Soil. 1992 ....................................... 67

Surface hardness readings (Clegg - 2.25 kg hammer). Beal ‘
Gardens. Sandy Loam Soil. 1993 ....................................... 68

Surface hardness readings (Clegg — 2.25 kg hammer). Beal
Gardens. Loamy Sand Soil. 1992 ....................................... 72

Surface hardness readings (Clegg - 2.25 kg hammer). Beal
Gardens. Loamy Sand Soil. 1993 ....................................... 73

Available soil phosphorus (Olsen) levels at the thatch, O to 7.5,
7.5 to 15.0, and 15.0 to 22.5 cm soil levels, 1990-1993 ............. 81

Ammonium acetate extractable potassium levels at the O to 7.5,
7.5 to 15.0, and 15.0 to 22.5 cm soil levels, 1990-1993 ............. 82

vii

1.3

1.4

1.5

1.6

1.7

3.1

3.2

3.3

3.4

3.5

3.6

LIST OF FIGURES

Soil phosphorus levels (Olsen) at the thatch layer of a creeping

bentgrass green ............................................................

Soil phosphorus levels (Olsen) at the 0-7.5 cm soil level of a
creeping bentgrass green .............................................

Soil phosphorus levels (Olsen) at the 7.5—15.0 cm soil level of a
creeping bentgrass green .............................................

Soil phosphorus levels (Olsen) at the 15.0-22.5 cm soil level of a
creeping bentgrass green .............................................

Soil potassium levels (Ammonium acetate extactable) at the

0-7.5 cm level of an annual bluegrass turf ..............................

Soil potassium levels (Ammonium acetate extactable) at the

7.5-15.0 cm level of an annual bluegrass turf ..........................

Soil potassium levels (Ammonium acetate extactable) at the

15.0-22.5 cm level of an annual bluegrass turf ........................

Surface Hardness Readings (Clegg). Forest Akers East Golf

Course practice green, 1992 ..............................................

Surface Hardness Readings (Clegg). Forest Akers East Golf

Course practice green, 1993 ..............................................

Surface Hardness Readings (Clegg). Sandy Loam Soil.

Beal Gardens. 1992 .......................................................

Surface Hardness Readings (Clegg). Sandy Loam Soil.

Beal Gardens. 1993 .......................................................

Surface Hardness Readings (Clegg). Loamy Sand Soil.

Beal Gardens. 1992 .......................................................

Surface Hardness Readings (Clegg). Loamy Sand Soil.

Beal Gardens. 1993 .......................................................

viii

l 1
12 _
13
22
23
24
58
59
69
70
74

75

CHAPTER ONE

Fertilization of Turf grass Using
High Pressure Water Injection

ABSTRACT

Traditionally,fertilization of turf grass has been performed using broadcast surface
application. However, the advent of high pressure water injection technology as a
turfgrass cultivation tool has made subsurface fertilization a possibility. Injection of
fertilizer nutrients phosphorus, potassium, and nitrogen was compared to surface
applications using soil nutrient tests and evaluation of turf responses. Deeper placement of
both P and K in the soil profile was found with injection compared to surface application.
Injection application of fertilizers resulted in no improvement or reduction in turf grass color
or quality. Increased clipping yields were seen from injection of urea nitrogen compared to
surface application. No difference in clipping yield or in plant tissue content of N or K was
observed from injection application of these nutrients. When applied at equal rates,
injection of phosphorus reduced phosphorus tissue content compared to surface
application, possibly due to reduced root weight densities in the 0 to 7.5 cm soil zone of
turf receiving injection application of phosphorus. Injection of nutrients is considered a
feasible means of placing nutrients deeper in the profile, especially when deeper roots have

reduced nutrient levels at the lower depths.

Fertilization of Turfgrass Using High Pressure Water Injection

Intmdnctlon

Fertilization of forages, food crops, and turf grasses has historically been performed
using broadcast applications. In an effort to combat the sometimes inefficient utilization of
fertilizer nutrients by crop plants after broadcast application, an alternative method of
fertilizer application, placement beneath the surface of the soil, has been studied
extensively. Most research in this area is concerned with food crops and forages, with
very little literature available on turf grass management.

Gyles et a1. (1985) lists as objectives of fertilizer placement to: 1) result in efficient
fertilizer use by the plant, 2) prevent fertilizer salt injury to plants, and 3) provide an
economical and convenient operation. Whether these objectives are ultimately achieved is
highly dependent on certain general conditions such as soil properties, physical and
chemical properties of the fertilizer material, and the extent and location of the plant root
system (Mengel et al., 1982).

Nitrogen is often applied to turf grass as urea because it is relatively inexpensive and
is rapidly used by plants. Plant analysis of creeping bentgrass (Agrostis palustris Huds.)
by Waddington et a1. (1972) indicated the highest plant N contents were obtained from
applications of urea compared to other N fertilizer sources. Banding urea fertilizer (placing
fertilizer in concentrated bands below the seed) has resulted in greater N efficiencies than
broadcast applications in corn (Zea mays L.) (Maddux et al., 1991), barley (Hodeum
vulgare L.) (Malhi and Nyborg, 1985), rice (Oryza sativa L.) (Wetselaar, 1984), and
bermudagrass (Cynodon dactylon L.) (Jackson and Burton, 1962). The literature
involving subsurfacenitrogen fertilizationin turf grass management is less extensive. King
and Skogley (1969), found no consistent differences between N placement treatments and

surface applications in terms of turf grass quality or clipping yield of a Kentucky bluegrass

3

(PoapratensisL) / red fescue (F estuca rubraL.) sod established from seed.

A common problem with broadcast applied phosphorus is the potential for a high
percentage of the phosphorus to be tied up or fixed into forms unavailable for immediate
plant utilization (Cook and Ellis, 1987). Band placement of P fertilizer for field crops
reduces soil-fertilizer contact, resulting in less fixation of the P by the soil (Gyles et al.,
1985; Sleight et al., 1984). Banding of phosphorus has been Shown to improve yields of
corn (Engelstad and Allen, 1971), potatoes (Solanum tuberosum L.) (Cook and Ellis,
1987), sugar beets (Beta vulgaris L.) (Cook and Ellis, 1987), and oats (Avena sativa L.)
(Sleight et al., 1984). Apparently, placement produces a concentration of soluble P needed
for early growth stimulation (Engelstad and Allen, 1971).

Very little published information is available concerning placement of P fertilizers in
turf grass management. Hipp and Graf f ( 1987) found that placement of P deeper than 3 cm
resulted in less than optimum growth on a bermudagrass turf grown on a clay soil,
however, depth of placement was found less critical on a sandy soil. The lack of research
in this area may be due to the fact that general turf grass quality has not been dramatically
affected by P applications (Christians et al., 1979).

In most finer textured soils, potassium is relatively immobile and does not react
with the soil to become unavailable to plants. Therefore, there is no consistent effect of
placement on efficient plant utilization of added potassium. Both agricultural crops and
turf grasses have been shown to exhibit no dramatic growth responses from potassium
fertilizationin soils containing adequate levels of available K+ (Gyles et al.; 1985, Beard,
1973). Waddington et a1. (1972) found K source or rate to have no effect on clipping
yields of creeping bentgrass, although K in clippings was increased with potassium
fertilization. Little benefit was shown from band placement of K compared to broadcast
application of K in corn (Heckrnan and Kamprath, 1992) or soybeans (Glycine max L.)
(Tisdale et al., 1985).

The increased efficiency in the use of fertilizers which can result from placing them

4

in selected zones of soil shows that the ability of crops to absorb nutrients varies
throughout the rooting zone (Newbould et al., 1971). Many plants, such as alfalfa
(Medicago sativa L.) (Peterson and Smith, 1973), clover (Trifolium pratense L.)
(Goodman and Collison, 1981), and perennial ryegrass (Lolium perenne L.) (Newbould et
al., 1971) absorb the majority of their nutrients from the upper areas of the soil profile.
According to Garcia et a1. (1988), nutrient placement is more important when positional
variability of a plant's root system exists, as in row crops such as corn, than when the soil
and root system is uniform. Rooting densities within the topsoil under well established
forage crops are so great that the distance a nutrient needs to travel to facilitate plant uptake
is small except for the most immobile nutrients (Barley, 1970). The dense nature of
turf grass stands suggests that similar rooting densities exist in these situations as well.

The advent of high pressure water injection cultivation technology (Murphy, 1990)
has made placement of fertilizers into shallow depths of soil under established turf
conditions a possibility. There is very little published information available concerning
fertilization using this process. Murphy and Rieke (1992) found late fall injection of N to
result in a more uniform green up response the next spring than broadcast applied N on a
fairway turf. Nitrogen injection also increased N recovery by 34% over broadcast
application in an early March clipping harvest. However, turf response to injection of
phosphorus and potassium fertilizers has not been recorded. The objectives of this
research were to determine effects of high pressure injection of N, P, and K on turf

response and soil tests compared to traditional surface applications.

Matedals_and_Methnds
Phosphorus
This study was initiated in August, 1990 at the Michigan State University Robert

Hancock Turf grass Research Center on a nine-year old 'Penncross' creeping bentgrass

5

(Agrostispalustris L.) green grown on a modified loamy sand soil containing 83.5% sand,
10.6% silt, and 5.9% clay. Initial soil tests for phosphorus were medium (35 kg/ha) and
low (59 kg/ha) for potassium. Soil pH was 7.3. Thatch thickness was approximately 20
millimeters.

A randomized complete block design was used with 4 replications of 5 treatments.
Injection treatments were applied using a prototype high pressure water injection machine
(Murphy, 1990) designed by the Tom Co., Minneapolis, MN. Liquid was injected to an
average depth of 14 cm at a pressure of 17.3 MPa through 10 injection nozzles (1.2 mm
orifice). Three passes with the injection unit were needed to cover a plot area. Nozzles
were spaced 76 mm apart and a forward speed of 3.2 km/hour placed the injection holes
approximately 75 mm apart. Surface treatments were applied using a C02 powered
sprayer. Annual treatments were: (i) control - no phosphorus fertilization; (ii) Water
injection cultivation only - no phosphorus fertilization; (iii) surface application of 5.3 g P /
m2; (iv) high pressure injection application of 5.3 g P / m2; and (v) high pressure injection
of 10.6 g P/ m2. Fertilization treatments were split into two separate applications with 1/2
rates applied in early August and late September of each year. Phosphoric acid (H3PO4)
was used as the phosphorus source.

Nitrogen was applied at 9.8, 14.6, 17.0, and 14.6 g N/m2 in 1990 - 1993,
respectively. Potassium was applied at 4.0 g / m2 in 1990 and 8.1 g N/m2 in 1991 - 1993.
The green was maintained at a 7.5 mm cutting height. Pesticides were applied as needed to
control insects, diseases, and weeds. Supplemental irrigation was provided daily to
prevent drought stress.

Soil samples for phosphorus analysis were collected on 2 Nov., 1990; 5 Aug. and
2 Nov., 1991; 8 Aug. and 2 Nov., 1992, and 11 Aug. and 4 Nov., 1993. Approximately
10 subsamples were taken from each plot and divided into sections representing thatch, O-
7.5 cm, 7.5-15.0 cm, and 15.0-22.5 cm depth zones. Subsamples for each depth zone

were combined into a representative sample. Each representative sample was then analyzed

6

for available phosphorus using the Olsen procedure (Olsen et al., 1954).

Five soil cores were taken from each plot on 10 Jun., 5 Aug., and 1 Nov., 1991; 6
Aug. and 4 Nov., 1992; and 12 Jun., 10 Aug., and 31 Oct., 1993 for root weight density
determinations. Each 5 cm2 by 22.5 cm deep core was divided into 3 sections each 7.5 cm
long. Roots were separated from soil with the hydropneumatic elutriation system
(Smucker et al., 1982).

Clippings were collected from an area approximately 1.5 m2, dried at 60C, and
weighed for yield measurements for the growth periods of 2 to 7 Aug., 7 to 19 Aug., 20
Aug. to 2 Sep., 3 to 20 Sep., and 21 Sep. to 10 Oct., 1991; 5 to 10 May, 2 to 7 Jul., 1 to 7
Aug., 9 to 16 Sep., and 2 to 10 Oct., 1992; and 1 to 6 May, 29 Jun. to 6 Jul., 9 to 12
Aug., 11 to 15 Sep., and 1 to 6 Oct., 1993. Turf was not mowed for extended periods of
time in order to magnify possible differences in yield measurements that may have been
occurring.

Plant tissue analysis of clippings was performed for phosphorus on samples
collected 20 Aug. and 10 Oct., 1991; 7 Jul., 7 Aug., and 10 Oct., 1992; and 6 May, 6 Jul.,
12 Aug. and 14 Oct., 1993. Clippings were ground through a 40 mesh screen and ashed at
500 C for 5 hours. Ash was then digested for 1 hour in 3N nitric acid and analyzed for
phosphorus content.

Turf was rated for color on a scale from 1 to 9 with 1 being brown, 5 acceptable,
and 9 dark green. Color ratings began 20 Apr., 1992 and were taken at 3 to 4 week
intervals until 27 Oct., 1992. In 1993 ratings were taken from 16 Apr. to 26 Oct.

Turf quality was rated on a scale from 1 to 9 with 1 being dead, 5 acceptable, and 9
excellent. Quality ratings were taken at3 to4week intervals from 8 Jul. to 24 Oct., 1991;

18 May to 27 Oct., 1992, and 16 Apr. to 26 Oct ., 1993.

Potassium

This study was initiated in August, 1990 at the Robert Hancock Turf grass Research

7

Center, Michigan State University, on an 11-year old annual bluegrass (Poa annua L. var.
reptans) turf growing on a sandy loam soil (fine - loamy, mixed, mesic, Typic Hapludalf).
Initial soil tests were high for phosphorus (131 kg / ha) and medium for potassium (131 kg
I ha). Soil pH was 7.3.

A randomized complete block design was used with 4 replications of 6 treatments.
Injection and surface applications were made as described for the phosphorus study.
Liquid was injected to an average depth of 12 cm at the same pressure and hole spacing as
the phosphorus study. Thirteen nozzles were used to inject the fertilizer solution and three
passes with the unit were required to cover a plot area. Annual treatments were: (i) control
- no potassium fertilization; (ii) water injection cultivation only - no potassium fertilization;
(iii) surface application of 12.2 g K/ m2; (iv) high pressure injection of 12.2 g K / m7- ; (v)
surface application of 24.4 g K / m2 ; and (vi) high pressure injection of 24.4 g K / m2.
Fertilization treatments were splitinto 2 separate applications with 1/2 rates applied in mid-
July and early September of each year. Potassium chloride (KCl) was used as the
potassium source.

Nitrogen was applied at 9.8, 14.6, 19.4, and 19.4 g N/m2 in 1990-1993,
respectively. Based on soil tests no supplemental phosphorus was applied throughout the
study. The turf was maintained at a 12.5 mm cutting height. Pesticides were applied as
needed to control insects, diseases, and weeds. Supplemental irrigation was applied daily
to prevent drought stress.

Soil samples for potassium analysis were collected 2 Nov., 1990; 23 Oct., 1991,
10 Jul. and 4 Nov., 1992; and 21 Jul. and 12 Oct., 1993. Approximately 10 subsamples
were taken from each plot and divided into sections representing 0-7.5 cm, 7.5-15.0 cm,
and 15.0-22.5 cm depth zones. Subsamples from each depth zone were combined into a
representative sample and analyzed for available potassium using the neutral normal
ammonium acetate extraction procedure (Knudsen et al. , 1982).

Clippings were collected from an area approximately 1.3 m2, dried at 60C, and

8

weighed for yield measurements for the growth periods of 20 Aug. to 5 Sep., 13 to 27
Sep., and 12 to 22 Oct., 1991; 9 to 15 May, 3 to 8 Jul., 1 to 7 Sep., and 2 to 7 Oct., 1992;
and 28 May to 3 Jun., 3 to 8 Jul., 27 Aug. to 4 Sep., and 24 to 29 Sep., 1993.

Plant tissue analysis of clippings was performed for potassium on samples collected
4 Sep. and 22 Oct., 1991; 16 Jul., 7 Sep., and 7 Oct., 1992; and 28 May, 7 Jun., 4 Sep.,
and 14 Oct., 1993. Clippings were ground through a 40 mesh screen and ashed at 500 C
for 5 hours. Ash was then digested for 1 hour in 3N nitric acid and analyzed for potassium
content.

Turf was rated for both color and quality as described for the phosphorus study.
Ratings were taken at 2 to 4 week intervals from 15 May to 22 Oct., 1992 and from 16
Apr. to 24 Oct., 1992. Turf quality ratings were taken from 31 Jul. to 24 Oct, 1991; 15
May to 22 Oct., 1992; and 16 Apr. to 24 Oct., 1993.

Nitrogen

The study was initiated in 1992 on an 11-year old 'Penncross' creeping bentgrass
green grown on a modified loamy sand containing 83.5% sand, 10.6% Silt, and 5.9% clay.

A randomized complete block design was used with 4 replications of 8 treatments.
Injection treatments were applied using the Hydroject 3000 manufactured by the Toro Co.,
Minneapolis, MN. Liquid was injected to an average depth of 12 cm at 21 MPa through
1.2 mm orifices. Nozzles on the unit were 76 mm apart and injection holes were spaced 25
mm apart. Surface treatments were applied as described for phosphorus and potassium
studies. Treatments were: (i) control - no nitrogen fertilization; (ii) water injection
cultivation only - no nitrogen fertilization; (iii) surface application of 2.4 g N/m2 for each
application date; (iv) surface application of 4.8 g N/mz; (v) injection application of 2.4 g
N/m2 ; (vi) injection application of 4.8 g N/m2 ; (vii) injection application of 4.8 g N/m2
with a late fall treatment; and (viii) surface application of 4.8 g N/m2 with a late fall

treatment. Treatments (ii) - (vi) were applied 27 Jun., 29 Jul., and 2 Sep., 1992 and 26

9

May, 2 Jul., 12 Aug., and 16 Sep., 1993. Treatments (vii) and (viii) were applied 27
Jun., 29 Jul., 2 Sep., and 24 Oct., 1992, and 2 Jul., 12 Aug., and 16 Sep., 1993. No
supplemental fertilization was applied. The green was maintained at 7.5 mm cutting height.
Pesticides were applied as needed to control weeds, insects, and diseases. Supplemental
irrigation was provided daily to prevent drought stress.

Clippings were collected from an area approximately 1.3 m2, dried at 60C, and
weighed for yield measurements for the growth periods of 24 to 31 Jul., 24 to 31 Aug.,
and 10 to 24 Oct., 1992; and 28 Apr. to 3 May, 29 Jun. to 1 Jul., 2 to 6 Jul., 24 to 29 Jul.,
10 to 16 Sep., and 1 to 10 Oct., 1993. On all dates except 6 Jul., 1993, clipping yields
were taken one month after treatment. The clipping yields on 6 Jul., 1993 were taken one
week after treatment. Plant tissue analysis was performed for total nitrogen on 1 Aug. and
31 Oct., 1992; and 30 Apr., 30 Jun., and 6 Jul. 1993 using the Kheldahl procedure
(Schuman et al., 1973).

Turf was rated for both color and quality as described for the phosphorus study. In
1992 both color and quality ratings were taken from 10 Jul. to 20 Oct. at 2 to 4 week
intervals. In 1993 ratings for both color and quality were taken from 15 Apr. to 7 Oct.

Analysis of variance was performed on all data and means were separated using

Fisher's protected LSD procedure at the 0.05 level of probability.

WWW
Phosphorus

Phosphorus soil test data is summarized in Figures 1.1-1.4 and data given in Table
A in the Appendix. Plots receiving no phosphorus fertilization had the lowest available
phosphorus levels in the thatch layer (approximately 20 mm thick) and upper 7.5 cm of soil

on all dates. The thatch layer revealed dramatic differences among P fertilization treatments

10

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(Figure 1.1). Significantly higher phosphorus levels were found in the thatch layer of the
plots receiving surface fertilization (5.3 g P / m2) compared to both rates of injection
fertilization. There was an annual cyclical fluctuation in available phosphorus levels in the
thatch layer of plots receiving surface fertilization. Soil P tests in the thatch layer in these
plots for the August dates (taken prior to the first fertilization treatment each year) showed
an average decrease of 109 kg available P / ha'l from November soil tests of the previous
year (taken after the second fertilization treatment each year). One explanation is that a high
amount of phosphorus is being mined from the thatch layer due to clipping removal from
these plots between fertilization treatments. Fluctuations of available phosphorus levels in
the thatch layer of plots receiving injection fertilization were evident, but not as dramatic.

In the O-7.S cm depth zone, plots receiving the high rate of injection fertilization
(10.6 g P / m2) had significantly higher available phosphorus levels than other treatments
on all dates except early in the study, Nov., 1990 and Aug., 1991. Comparison between
surfaceandinjection fertilization treatments at the low rate of P fertilization (5.3 g P / m2)
revealed equal availableP levels on each date except Aug. 1992 and Aug. 1993. Both of
these dates were prior to the first semi-annual fertilization treatment. At the end of each
season, after fertilization treatments, these differences were no longer present. Reasons for
these differences are speculative. Perhaps movement of phosphorus from the thatch layer
to this depth zone of the surface fertilized plots may be an explanation. Due to the fact that
the phosphorus was injected to an average depth of 14 cm, less phosphorus was present in
the thatch layer of plots receiving the low rate of injected phosphorus. Therefore, less, if
any, downward movement of phosphorus may have occurred between fertilization
treatments in these plots, resulting in lower available P levels. In the surface treated plots,
however, available P levels increased with each soil test in plots receiving surface
fertilization, with the exception of the Aug. 1993 tests. This suggests in these plots,
phosphorus is moving downward out of the thatch layer to the 0-7 .5 cm soil depth.

Injection of phosphorus at both rates increased the level of available phosphorus in

15

the 7.5-15 cm depth zone with each annual application. Comparison of plots receiving
surface fertilizationwith the control and WIC plots consistently revealed equal available P
levels. This was true even after the fourth year of treatment. Phosphorus applied to the
surface is staying in the thatch layer and the upper 7.5 cm of the soil profile. Clearly,
injection fertilization is effective at placing phosphorus past this zone in this loamy sand
soil.

In the 1522.5 cm depth zone, it was seen that after the first year of fertilization
treatments, available P levels in plots receiving the high rate of injection were significantly
higher than those found in both the check and WIC only plots. After the third year of
fertilization treatments, the low rate of injection increased available P levels compared to
both the check and WIC only plots. Surface application of phosphorus did not affect
available P levels at this soil depth as compared to the control and WIC only plots. It is
evident that there was downward movement of phosphorus past the depth of injection at
both the high and the low rate of fertilization.

Frequent color differences were seen among control plots and plots receiving
phosphorus fertilization (Table 1.1). Purpling of leaf tissue, a common symptom of
phosphorus deficiency, often resulted in lower color ratings in control plots. These color
differences were more dramatic in late spring and early summer when soil temperatures are
traditionally lower. An explanation may be lowered phosphorus availability due to a
decrease in microbial breakdown of organic phosphorus sources. As soil temperatures
rose, microbial activity increased, making more organic phosphorus available for plant
uptake. Therefore, color rating increased, although deficiency symptoms persisted. On
several dates, WI C only plots had significantly higher color ratings than control plots. Soil
P levels deeper in the soil profile for the check and WIC only plots (see Table A,
Appendix) were higher than those found in the surface soil. Treatment of the soil with
water injection cultivation may have caused enough movement of soil from deeper in the

profile to make more phosphorus available for plant uptake, eliminating the symptoms of

16

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17

phosphorus deficiency seen in control plots. These differences did not show up in soil test
results, however. No consistent differences in color were found among phosphorus
fertilization treatments.

Injection of phosphorus at either rate did not affect clipping yields as compared to
other treatments (Table 1.2). Control plots tended to have slightly lower clipping yields
thanother treatments, although on only one date, 7 Aug., 1992, was the clipping yield in
these plots significantly lower than all other treatments. It can be concluded that injection
of phosphorus, even at a high rate (10.6 g P/ m2) did not cause a reduction in top growth
of a creeping bentgrass stand on this soil.

Root weight densities (RWD) were significantly reduced compared to the control in
the 0-7.5 cm depth zone from injection of phosphorus at both rates of phosphorus
fertilization in Nov. 1991, Nov. 1992, and Nov. 1993 (Table 1.3). The WIC only
treatment did not reduce RWD in this depth zone on any date. This suggests possible root
injury from injection of the phosphorus source used (phosphoric acid). Significantly
lower RWD's were found in plots receiving injection P fertilization at both the high and
low rate compared to plots receiving surface P fertilization in Nov. 1992, Jun. 1993, Aug.
1993, and Nov. 1993. On no dates did surface application of phosphorus significantly
decrease RWD compared to control plots.

Percent of total roots in the O—7.5 cm depth zone of injection fertilized plots
decreased in Aug. 1993 and Nov. 1993 compared to surface fertilized plots. However,
percent of total roots in the 7.5-15 cm zone increased with injection fertilization compared
to surface fertilization in Nov. 1992, Aug. 1993, and Nov. 1993. The water injection
cultivation only treatment increased the percent of total roots compared to plots receiving
surface fertilization in the 7.5-15 cm zone in Aug. 1993 and Nov. 1993. This may suggest
that rootsare proliferating in the thatch and upper 7.5 cm of soil in plots receiving surface
fertilization, while water injection cultivation, both with and without phosphorus, may be

causing a redistribution of a portion of the total root system to deeper in the soil profile.

18

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20

A high concentration of roots, typically 80 to 90 percent of the total root weight,
was found in the O to 7.5 cm depth zone. Root weight densities decreased with
progression down through the soil profile. Ultimately, a very small percentage of the total
root weight, 1.5 to 9 percent, was found in the 15.0 to 22.5 cm depth zone. This may
explain the higher available soil phosphorus levels deeper in the soil profile in the control
and WIC only plots. Without supplemental phosphorus applications, the dense root
system in the surface layer of these plots has extracted a major portion of the available
phosphorus. With less roots deeper in the soil, however, less of the available phosphorus
has been extracted and higher available phosphorus contents were found.

Plant tissue analysis showed lower phosphorus content in clippings taken from
plots receiving no phosphorus fertilization on every date except 6 Jul. and 12 Aug. 1993
(Table 1.4). A consistent difference was found between clippings taken from injection
fertilized plots and clippings taken from surface fertilized plots at the low rate of P
fertilization (5.3 g P/m2). On every date except 6 Jul. and 12 Aug. 1993, significantly
higher phosphorus contents were found in clippings taken from surface fertilized plots.
This may be due to the lower root weight densities found in the upper 7.5 cm of soil in the
plots receivinginjection fertilization. On all dates however, P contents in clippings taken
from injected and surface fertilized plots at the low rate are well within the tissue content
sufficiency range described by Jones (1980). On every date except 20 Aug. 1991 and 7
Aug. 1992, clippings taken from plots receiving the high rate of injection fertilization had

equal phosphorus contents compared to clippings taken from surface fertilized plots.

Potassium

Soil test levels for ammonium acetate extraction of potassium are summarized in
Figures 1.5-1.7 and in Table B in the Appendix. In the O-7.S cm depth zone, plots
receiving no potassium (control and WIC only plots) had significantly lower available

potassium levels than plots receiving potassium on all dates. The values found in the

21

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25

control and W1C only plots were still well above those considered low in potassium (50-
60-70 kg available K / ha) (Turner, 1980). At both the low and high rates of potassium
fertilization, plots receiving surface applications showed a trend of having higher available
K levels than plots receiving injection fertilization. This could be expected, as potassium
applied by injection reached as deep as 12 cm. As with the phosphorus study, there was an
annual cycle in the available potassium tests. Since clippings were not removed from these
plots, it is assumed the lower potassium tests in summer just before the first application
each year was the result of either leaching or minor fixation of potassium by the soil.

In the 7.5-15 cm depth zone (Figure 1.6), there were lower available K levels in the
control and WIC only plots. These levels stayed highly similar throughout the study. At
the low rate of K fertilization (12.2 g K/mz), injection increased K levels over surface
fertilized plots on only one date (Oct. 1991). At the high rate of K fertilization (24.4' g
K/mz), however, injection significantly increased K levels compared to surface fertilization
in Oct. 1990, Oct. 1991, Oct. 1992, and Oct. 1993. These four soil test dates were all after
annual fertilization treatments. Soil tests taken before fertilization treatments in Jul. 1992
and Jul. 1993 do not show these differences. Apparently, potassium applied to the surface
has moved downward in the soil profile, especially at the high rate of application.

No consistent differences among treatments were found in the lS-22.5 cm depth
zone, except at the high rate of potassium fertilization. Higher K levels were found in plots
receiving injection fertilization compared to surface fertilization in Oct. 1990, Oct. 1991, -
Jul. 1992, and Oct. 1993. Despite these differences, it is still apparent that at both rates,
potassium applied using surface and injection methods has moved through the soil profile.
In plots which received the low rate of K fertilization, available soil K levels in the 1.5-22.5
cm depth zone increased an average of 43% after 4 years of treatments. At the high rate,
this average increase was 102%.

No differences in color, quality, or clipping yield (data not shown) were found

among treatments on any date, regardless of whether the plot received no K, surface K, or

26

injection K fertilization. Rate of potassium fertilization also had no effect on color, quality,
or clipping yield. Sufficient potassium was available for turf grass growth in this sandy
loam soil such that application of additional potassium, regardless of rate or method of
application, produced no significant color or growth response.

Plant tissue analysis on 22 Oct. 1991, 7 Oct. 1992, and 4 Sep. 1993 revealed lower
potassium contents in clippings taken from plots receiving no potassium fertilization (Table
1.5). Despite having lower potassium contents, the potassium levels in these clippings are
within the tissue content sufficiency range described by Jones (1980). No differences in
potassium content of clippings were found among treatments which received potassium on

any date regardless of method or rate of fertilization.

Nitrogen

The creeping bentgrass green on which this study was performed received no
nitrogen fertilization in the year prior to the initiation of the study (1991). Response to
nitrogen fertilization in July, 1992 was extremely rapid and dramatic. In 1992, at the high
rate of nitrogen fertilization (4.8 g N/mz), plots receiving injection fertilization exhibited a
localized response in the turf immediately surrounding injection holes. This localized
response, which gives evidence the nitrogen is not spreading laterally in the soil
immediately after application, led to a striped appearance of the turf, which lasted 2 to 3
weeks after application. Response to surface nitrogen applications was a uniform green
up. The stn'ped appearance of the turf in the injected plots led to significantly lower color
ratings on several dates compared to plots receiving surface application (Table 1.6). At the
low rate of nitrogen fertilization however, striping effects from injection of nitrogen were
not as dramatic and did not result in lowered color ratings compared to surface application.
On all dates in 1992 and 1993, plots receiving no nitrogen fertilization had lower color
ratings than all other treatments.

Plots which had received late fall N fertilization in 1992 exhibited early spring green

27

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29

up in 1993 and showed significantly higher color ratings than all other treatments on 15
Apr. and 14 May. No differences in color were seen between late fall injection and surface
fertilization treatments on these two dates, however. In 1993, localized response to
injection of nitrogen was less apparent compared to 1992, and striping of turf was minimal.
No consistent differences in color were seen between injection and surface fertilized plots at
either rate of N fertilization. Perhaps there was enough residual nitrogen in the soil from
the 1992 applications to mask the localized response seen after injection.

Si gnificantly lower clipping yields were found in plots receiving no nitrogen
fertilization on all dates (Table 1.7). At both the low and high rates of N fertilization,
higher clipping yields were found on several dates in plots receiving nitrogen injection
compared to plots receiving surface fertilization. Although nitrogen applied to the surface
was watered in immediately following application, a small degree of volatilization may still
have occurred. Injection of nitrogen may decrease these volatilization losses, resulting in
increased clipping yields. Plots which received late fall N fertilization treatments in 1992
had significantly higher clipping yields than other treatments in an early spring harvest 3
May 1993. On this date a comparison of the two late fall treatments showed significantly
higher clipping yields in plots which had received nitrogen injection fertilization compared
to surface application.

Total nitrogen content in clippings for both 1992 and 1993 is summarized in Table
1.8. Inconsistent results were seen among the 5 dates. On 2 dates (1 Aug., 1992 and 30
Jun., 1993), no differences in nitrogen were seen among treatments. Three dates (31 Oct.,
1992, 30 Apr. and 6 Jul., 1993) revealed differences among treatments, however. Lower
nitrogen content was generally found in clippings from the control and WIC only plots. On
no dates did method of application affect N content in the clippings. This was true at both

the high and low rates of nitrogen fertilization.

In summary, high pressure water injection is an effective method of applying

30

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32

fertilizers to turfgrass, especially P and K. When compared to surface application of
fertilizers, water injection fertilization was equally sufficient in maintaining turf quality,
growth, and plant tissue nutrient content. Water injection placed nutn’ents deeper in the soil
profile, especially phosphorus, which is less susceptible to leaching than nitrogen or
potassium in most soils. Surface applications of phosphorus tended to be held in the thatch
and the upper 7 cm of the soil profile even at the relatively high rates applied in this study.

Injection of potassium initially increased levels of K deeper in the soil profile.
However, potassium applied on the surface moved downward in the profile past the
surface 7.5 cm. Injection of nitrogen increased clipping yields, which gave evidence that
greater nitrogen efficiency may result when applied using water injection. In addition to
receiving fertilization from water injection, the turf stand may be benefiting from
improvement in soil physical properties such as decreased bulk density, and increased
porosity and water conductivity (Murphy, 1990). This observation needs further
investigation.

In the creeping bentgrass green in the phosphorus study, 80-90% of the creeping
bentgrass root mass resided in the surface 7.5 cm of the soil profile. This brings up the
important aspect of the ideal depth of fertilizer placement in similar situations. Injection of
nutrients past this zone of concentrated roots may be an inefficient use of fertilizer.
Although roots are present below this zone that are capable of nutrient uptake, they exist in
limited concentration. Therefore, much of the fertilizer placed in this zone may not be taken
up by the plant, and in the case of nitrogen and potassium, could be lost through leaching.

This is an important issue which deserves attention in the future.

 

33

When

Barley, KR 1970. The configuration of the root system in relation to root uptake. Adv. in
Agron. 22: 159—201.

Beard, J.B. 1973. Turf grass: Science and culture. Prentice-Hall, Englewood Cliffs, NJ.
658 pp.

Christians, N.E., D.P. Martin, and J.F. Wilkinson. 1979. Nitrogen, phosphorus, and
potassium effects on quality and growth of Kentucky bluegrass and creeping
bentgrass. Agron. J. 71: 564-567.

Cook, R.L., and B.G. Ellis. 1987. Soil management. A world view of conservation and
production. John Wiley & Sons, New York. 413 pp.

Engelstad, OR, and SE. Allen. 1971. Ammonium pyrophosphate and ammonium
orthophosphate as phosphorus sources: effects of soil temperature, placement, and
incubation. Soil Sci. Soc. Am. Proc. 35: 1002-1004.

Garcia, F., R.M. Cruse, and A.M. Blackmer. 1988. Compaction and N placement effect

on root growth, water depletion, and nitrogen uptake. Soil Sci. Soc. Am. J. 52:
792-798.

Goodman, P.J., and M. Collison. 1981. Uptake of P32 labelled phosphate by clover and
ryegrass growing in mixed swards with different N treatments. Annals of Appl.
Biol. 98: 499-506.

Gyles, W.R., K.I... Wells, and JJ. Hanway. 1985. Modern techniques in fertilizer
application. p. 521-560. In O.P. Engelstad (ed.) Fertilizer technology and use.
Soil Sci. Soc. Am. Madison, WI.

Heckman, J.R., and E.J. Kamprath. 1992. Potassium accumulation and corn yield related
to potassium fertilizer rate and placement. Soil Sci. Soc. Am. J. 56: 141- 148.

Hipp, B.W. and PS. Graff. 1987. Phosphorus fertilizer requirements of turf grass
seeded on disturbed urban soils. In Agronomy Abstracts. p. 135. ASA. Madison,
WI.

Jackson, J.A., and G.W. Burton. 1962. Influence of sod treatment and N placement on the
utilization of urea N by coastal bermudagrass. A gron. J. 54: 47-49.

Jones, J.R. Jr. 1980. Turf analysis. Golf Course Management. 48:(1):29-32.

King, J.W., and CR. Skogley. 1969. Effect of nitrogen and phosphorus placements and
rates on turf grass establishment. A gron. J. 61: 4-6.

Knudsen, D., G.A. Peterson, and PF. Pratt. 1982. Lithium, sodium, and potassium.
p. 225-246. In A.L.Page, R.I-I. Miller, and DR. Keeney (eds.) Methods of Soil
Analysis, Part 2. Chemical and Microbiological Properites. ASA and SSSA,
Madison, WI.

34

Maddux, L.D., C.W. Raczkowski, D.E. Kissel, and D.L. Barnes. 1991. Broadcast and
subsurface-banded urea N in urea ammonium nitrate applied to corn. Soil Sci. Soc.
Am. Proc. 55: 264-267.

Malhi, SS, and M. Nyborg. 1985. Methods of placement for increasing the efficiency of
N fertilizers applied in the fall. A gron. J. 77: 27-32.

Mengel, D.B., D.W. Nelson, and D.M. Huber. 1982. Placement of nitrogen fertilizers for
no-till and conventional till corn. Agron. J. 74: 515-518.

Murphy, J.A. and RE. Rieke. 1992. Evaluating additional management uses for high
pressure water injection. In A gron. abstr. ASA, Madison, WI. p. 174.

Murphy, J.A. 1990. The influence of cultivation on soil properties and turf grass growth.
Ph.D. diss. Michigan State Univ., East Lansing. 77 pp.

Newbould, P., R. Taylor, and KR. I-Iowse. 1971. Absorption of phosphate and calcium
from different depths in soil by swards of perennial ryegrass. J. British Grass.
Soc. 26: 201-208. .

Olsen, S.R., C.V. Cole, ES. Watanabe, and LA. Dean. 1954. Estimation of available
phosphorus in soils by extraction with sodium bicarbonate. U.S. Dep. of A gric.
Circ. 939.

Peterson, L.A., and D. Smith. 1973. Recovery of K2804 by alfalfaafter placement at
different depths in a low fertility soil. A gron. J. 65: 769-772.

Schuman, G.E., M.A. Stanley, and D. Knudsen. 1973. Automated total nitrogen analysis
of soil and plant samples. Soil Sci. Soc. Am. Proc. 37:480-481.

Sleight, D.M., D.H. Sander, and G.A. Peterson. 1984. Effect of fertilizer phosphorus
placement on the availability of phosphorus. Soil Sci. Soc. Am. Proc. 48: 336-
340.

Smucker, A.J., S.L. McBumey, and AK. Srivastava. 1982. Quantitative separation of
roots from compacted soil profiles by the hydropneumatic elutriation system.
Agron. J. 74: 500-503.

Tisdale S.L., W.L. Nelson, and JD. Beaton. 1985. Soil fertility and fertilizers. MacMillan
Publishing Corp.

Waddington, D.V., E.L. Moberg, and J.M. Duich. 1972. Effect of N source, K source
and K rate on soil nutrient levels and the growth and elemental composition of
Penncross creeping bentgrass, Agrostispalustris Huds. A gron. J. 64: 562-566.

Wetselaar, R. 1984. Deep point placed urea in a flooded soil. A mechanistic view. In
Proceedings of the workshop on urea deep placement technique.

 

3S

CHAPTERTWO

High Pressure Injection of Wetting Agents in Sand-Based Greens

ABSTRACT

The phenomenon of localized dry spot (LDS) is a problem frequently found on'
sand-based greens. The application of wetting agents in these situations is a common
practice used toaid in the control of LDS. Applications of wetting agents using traditional
surface treatment were compared to those using high pressure water injection based on soil
moisture tests and evaluation of turf response. I-IydroWet was effective in preventing
formation of localized dry spot, especially when applied at a high rate (5.1 ml/m2). Both
injection and surface applications of HydroWet were equally effective in terms of
maintaining turf quality and gravimetric soil moisture contents. When a less effective
wetting agent was applied, lower water drop infiltration times in soil 1.25 cm below the
thatch layer were found in soil cores receiving injection application of wetting agents. The
longest water dropinflltration times were found in the thatch layer and were on average 10

times greater than those found in soil 1.25 cm below the thatch layer.

36

High Pressure Injection of Wetting Agents In Sand-Based Greens

Introduction

The phenomenon of localized dry spot (LDS), sometimes referred to as dry patch,
has been well documented. Cases have been reported in pasture soils in Australia (Bond,
1969), bushlands in California (Holzhey, 1969), burned over areas of forest soils (Osborn
et a], 1964), and citrus orchards in Florida (Wander, 1949). However, the most frequent
occurrences have been in turf grass areas (York and Baldwin, 1992). Localized dry Spots
are almost always found on areas with coarse-textured sandy soils, although not exclusively
(Bond,l969).

Localized dry spot is a term which is commonly used to describe the occurrence of
an irregular area of turfgrass which shows signs typical of drought stress (Kamok and
Tucker, 1989). With the increased use of sand-based putting greens and sand topdressing
programs, LDS has become a major problem for golf course managers. Circumstantial
evidence points to soil fungi as causal agents of localized dry spots (York and Baldwin,
1992). Another suggested source of LDS is the production of a water repellent coating by
microorganisms during organic matter decay (Wilkinson and Miller, 1978). This material
was thought to be an organic acid (fulvic acid), which when dry, becomes extremely
hydrophobic . Use of an electron microscope has shown sand from LDS or hydrophobic
areas to have a covering or coating over much of the particle. Inspection of sand taken
from healthy or non-hydrophobic areas revealed clean, relatively smooth surfaces (Bond
and Harris, 1964). No firm link, however, has been provided which can unquestionably
connect the presence of microbes with the production of water repellent molecules (York
and Baldwin, 1992).

Using a water drop infiltration time test on soil samples taken from LDS-afflicted

areas, Letey (1969) indicated that the area of maximum hydrophobicity (non-wettability)

37

occurs just below the thatch-soil interface. Deeper in the soil there is less effect (Henry and
Paul, 1978). Soil found in the root zone beneath localized dry spot afflicted areas is often
extremely dry (Baldwin, 1990). Once the turf begins to exhibit symptoms of LDS the
problem is usually difficult to correct (York and Baldwin, 1992). Therefore, prevention,
by keeping the soil profile moist, is viewed as the most effective defense against formation
of LDS (Wilkinson and Miller, 1978).

This is not always possible, however, and dry spots do still develop. In the
1950’s, soap and detergent solutions were sometimes used to aid the percolation of water
into LDS affected areas. These chemicals were not designed for this purpose, however,
and had many undesirable side effects such as severe phytotoxicity and adverse effects on
soil structure (Baldwin, 1989). Since then, commercial products specifically designed for
use on turf grass have been developed. These products, commonly called surfactants
(surface active agents) or wetting agents are now commonly used to assist in alleviating the
severity of the symptoms expressed in areas of turf affected by LDS (York and Baldwin,
1992).

High pressure water injection was developed to give turf managers a cultivation tool
that could be used frequently, while imparting minimal disturbance to the turf surface
(Murphy, 1990). This technology, referred to as water injection cultivation (WIC), also
offers the potential to place materials such as wetting agents deeper in the soil profile.
Wetting agents have been reported to improve soil percolation, infiltration, and drainage,
help wetting of LDS affected areas, reduce evapotranspiration rates, minimize dew
formation, decrease disease incidence, and reduce thatch buildup (Petrovic, 1985). Very
little publishedinformationis available concerning application of wetting agents using high
pressure water injection. In work done by Murphy and Rieke (1992), injection of wetting
agent following a rainfall event resulted in an increase in gravimetric soil moisture content
of 132% compared to plots receiving no wetting agent. The majority of research on the

application of wetting agents, however, has been done with their application to the surface

38

of turf areas. The objective of this research was to compare high pressure injection of

wetting agents to conventional surface application by observing turf and soil responses.

W

A study was initiated in Aug. 1992 at the Michigan State University Robert
Hancock Turf grass Research Center on an 11-year old Penncross creeping bentgrass
(Agrastispalustris Huds.) green grown on a modified loamy sand soil containing 83.5%
sand, 10.6% silt, and 5.9% clay.

A completely randomized design was used with 4 replications of 10 treatments.
Water injection treatments were applied using the Hydroject 3000‘“, manufactured by the
Toro Co., Minneapolis, MN. Liquid was injected to an average depth of 120 mm at 21
MPa through 1.2 mm orifices. Nozzles on the unit were 76 mm apart and injection holes
were spaced 75 mm apart Surface treatments were applied using a C02 powered sprayer.
Two wetting agents were applied in this study: HydroWet from the Kalo Co., and
Hydrozone from WMC Products Inc. Treatments were (i) control; (ii) water injection
cultivation only - no wetting agent application; (iii) Hydrozone, injected at a rate of 1.3
ml/m2 ;(iv) Hydrozone, injected ata rate of 5.1 ml/m2 ; (v) Hydrozone, surface applied at
a rate of 1.3 ml/m2 ; (vi) Hydrozone, surface applied at a rate of 5.1 ml/m2 ; (vii)
HydroWet, injected at a rate of 1.3 mI/m2 ;(viii) HydroWet, injected at a rate of 5.1 ml/m2
;(ix) HydroWet, surface applied at a rate of 1.3 ml/m2 ; and (x) HydroWet, surface applied
at a rate of 5.1 ml/mz. Application dates were 18 Aug., 1992; and 16 Jun. and 27 Jul.,
1993. The plot area was irrigated following treatment application to assist wetting agents
into the soil profile.

Nitrogen was applied at 9.8 and 14.6 g N/m2 in 1992 and 1993, respectively.
Potassium was applied at 8.1 g K/m2 in both 1992 and 1993. Phosphorus was applied at
5.3 g P/m2 in both 1992 and 1993. Pesticides were applied as needed to control insects,

39

diseases, and weeds. Supplemental irrigation was not applied in order to augment
development of LDS.

Soil samples were collected for gravimetric moisture analysis on 26 Aug., 16 Sep.,
and 28 Oct., 1992, and 23 Jun., 21 Jul., 26 Jul., 12 Aug., 24 Aug., 4 Sep., and 24 Sep.,
1993. Five subsamples were taken from the top 7.5 cm of each plot and combined into a
representative sample. Samples were taken from random locations within a plot. Each
representative sample was weighed, dried at 105 C for 24 hours, and weighed again for
gravimetric moisture analysis.

Turf was rated for quality on a scale of 1 to 9 with 1 = brown, 5 = minimum
acceptable, and 9 = excellent. Turf quality ratings were taken on 26 Aug., 15 Sep., 8 Oct.,
1992, and 16 Jun., 30 Jun., 10 Jul., 21 Jul., 7 Aug., 28 Aug., 10 Sep., 24 Sep., and 7
Oct., 1993. Five soil cores were selected from the driest area in each plot based on
visual observations on 24 Aug., 1993. These cores were then air dried, and analyzed for
water drop infiltration time (Letey, 1969) at thatch, 1 cm, and 7 cm depths.

All tests were subjected to analysis of variance and means were separated using

Fisher's protected LSD procedure at the 0.05 level of probability.

Winn

Turf quality ratings are summarized in Table 2.1. Analysis of 1992 data revealed
high quality ratings and no consistent differences among treatments. A small amount of
phytotoxicity was seen in plots receiving the high rate of HydroWet on 26 Aug., resulting
in lower quality ratings than other treatments. These differences disappeared by the next
ratings taken, 15 Sep. No formation of localized dry spots occurred, most likely due to
frequent rainfall received in the months of August, September, and October.

Initial quality ratings in 1993 showed no differences among treatments, with
extremely high quality found in all plots. As warmer weather progressed, a decrease in

rainfall may have precipitated localized dry spot formation. By 21 Jul., differences among

40

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41

treatments were evident. Extreme variability, however, resulted in limited statistical
significance. The most severe dry spot formation was found in control plots, or those
receiving water injection cultivation (WIC) only, and surface or injection application of the
low rate of Hydrozone (1.3 ml/mz). Moderate development of LDS occurred on several
dates in plots receiving the injected or surface application of the high rate of Hydrozone
(5.1 ml/mz) as well as in plots receiving the injected or surface application of the low rate
of HydroWet (1.3 ml/mz). Little or no LDS formation occurred in plots receiving surface
orinjected applications of the high rate of HydroWet. There was no difference in quality
ratings between surface and injection treatments. Frequent rainfall in September and
Octobercaused a reduction in the severity and amount of LDS. Consistent differences in
quality among treatments during these two months were not evident.

Gravimetric soil moisture data are given in Table 2.2. As with quality ratings,
analysis of 1992 data revealed no differences among treatments.

Initial soil moisture data in 1993 on 23 Jun. showed no differences among
treatments. Based on visual observations of the plot area, localized dry spot formation did
develop but extreme variability made detection of a definitive trend in soil moisture results
difficult. The highest soil moisture contents in 1993 were found in plots receiving the high
rate of HydroWet. No consistent differences between methods of application of HydroWet
were apparent, however. The success of these treatments at maintaining a steady level of
soil moisture explains the lack of localized dry spot formation in these plots. Plots injected
with the high rate of Hydrozone had higher soil moisture contents than plots receiving the
high rate surface application on only two dates (21 and 26 Jul.). Injection of the high rate
of Hydrozone improved soil moisture over the check on 3 dates. On no dates was this seen
with the high rate of surface application of Hydrozone. This suggests injection of certain
wetting agents is more effective at maintaining soil moisture than surface applications.

Water drop infiltration times from soil cores taken 24 Aug. 1993 are given in Table

2.3. As with quality and soil moisture data, variability was high. Uniformity in plots

42

 

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44

treated with effective wetting agent treatments was good, therefore, there was no apparent
localized dry spot in some plots. Soil taken from plots treated with HydroWet tended to
have the lowest water drop infiltration times in both the thatch layer and 1.25 cm below the
thatch layer. Infiltration times in soil taken from plots receiving injection of Hydrozone at
the high rate had significantly lower infiltration times than soil taken from plots receiving
surface application of the high rate of Hydrozone in both the thatch layer and 1.25 cm
below the thatch layer. The same results were found for the low rate of Hydrozone,
however only in the zone 1.25 cm below the thatch layer. Surface applications of low rates
of wetting agents may not be penetrating past the thatch layer, limiting water infiltration into
the soil. Injection of wetting agents can be an effective method of distributing the wetting
agents through the surface hydrophobic layer, improving the wettability of soil and
reducing susceptibility to localized dry spot.

Results of this study are difficult to interpret due to the variability and nature of
localized dry spot formation. It can be stated that the application of wetting agents,
especially HydroWet applied at a high rate, is an effective means of preventing localized
dry spot formation on sand based putting greens. Both injection and surface applications
of wetting agents were equally effective in terms of maintaining turf quality by preventing
LDS. Injection and surface applications of a high rate of HydroWet were equally effective
at maintaining ahigher level of soil moisture than the control. Injection of the high rate of
Hydrozone, however, was more effective than surface application at maintaining a higher
level of soil moisture than the control on several dates. Injection of high rates of certain
wetting agents may be more effective at maintaining soil moisture than their surface
application. Higher water drop infiltration times in soil immediately below the thatch layer
in soil taken from plots receiving the low rate of surface applied Hydrozone suggest that
low rates of wetting agents may not penetrate past the thatch layer, limiting water

infiltration into the soil.

45

Injection of wetting agents is an effective method of distributing the wetting agents
through the surface hydrophobic layer, improving the wettability of soil and reducing
susceptibility to localized dry spot. It is important to note, however, that deep placement of
wetting agents may be an inefficient use of these materials. With the 'water injection unit
used in this study, wetting agents were injected to an average depth of 12 cm. This could
be placing much of the wetting agent past the zone where it is most needed, which is just
below the thatch-soil interface (Letey, 1969). The study of injection of wetting agents to

shallower depths deserves further attention.

46

Wind

Baldwin, NA. 1990. Wetting agent programmes for alleviation of dry patch of f i ne turf.
J. of the Sports Turf Res. Inst. 66: 180-181.

Baldwin, NA. 1989. Dry patch and wetting agents. The Groundsman. 42(5): 16.

Bond, RD. 1969. The occurrence of water repellant soils in Australia. p. 1-6. In
Proc. Symp. on Water Repellant Soils. Univ. Calif. Riverside.

Bond, RD, and JR. Harris. 1964. The influence of the microflora on physical properties
of soils. Austr. J. of Soil Res. 2: 111-112.

Henry, M.J., and J.L. Paul. 1978. Hydrophobic soils on putting greens. California
Turf grass Culture. 28(2): 9-11.

Holzhey, CS. 1969. Water repellant soils in southern California. p 30-41. In Proc.
of the Symp.on Water Repellant Soils. Univ. Calif. Riverside.

Kamok, K.J., and K.A. Tucker. 1989. The cause and control of localized dry spots on
bentgrass greens. Golf Course Management. 57(8): 28-34.

Letey, J. 1969. Measurement of contact angle, water drop penetration time and critical
surface tension. p. 43-47. In Procedings of the Symposium on Water Repellant
Soils. Univ. Calif. Riverside.

Murphy, J.A., and RE. Rieke. 1992. Evaluating additional management uses for high
pressure water injection. In Agron Abstr. Amer. Soc. A gron., Madison, WI.
p.174.

Murphy, J .A. 1990. The influence of cultivation on soil properties and turf grass growth.
PhD. diss. Michigan State Univ., East Lansing.

Osborn, J.F., R.E. Pelishek, J.S. Krammes, and J. Letey. 1964. Soil wettability as a
factor in erodibility. Soil Sci. Soc. Am. Proc. 28: 294—295.

Petrovic, M.A. 1985. Wetting agents. Weeds, Trees, & Turf. 24(7): 40-4284.

Wander, I.W. 1949. An interpretation of the case of water repellant sandy soils found in
citrus groves in central Florida. Science 110: 299-300.

Wilkinson, J.F., and RH. Miller. 1978. Investigation and treatment of localized dry spots
on sand golf greens. A gron. J. 70: 299-304.

York, C.A., and NA. Baldwin. 1992. Dry patch on golf greens: a review. J. Sportsturf
Res. Inst. 68: 7-19.

47

CHAPTER THREE

Water Injection Cultivation Effects on Surface
Hardness and Turf grass Quality

ABSTRACT

Wear and compaction caused by concentrated traffic and equipment ultimately affect
turf grass growth, quality, and vigor. Water injection cultivation can help alleviate adverse
effects of traffic stress by lowering bulk density and improving porosity and hydraulic .
conductivity of the soil. A cultivation program using frequent applications of water
injection cultivation was employed on two high traffic sites to determine effects on
turf grass quality and surface hardness. Water injection cultivation applied as frequently as
every 2 weeks had no effect on turf quality. Ball roll on a putting green increased an
average of 22% after application of water injection cultivation. Surface hardness readings,
as given by the Clegg soil impact tester, decreased immediately following application of
water injection cultivation. Duration of this effect on most occasions lasted less than two

weeks due to recompaction of soil from constant traffic.

48

Water Injection Cultivation Effects On Surface Hardness and Turf Quality

Introduction

As the use of areas such as athletic fields and golf courses increases, so does the
need to address the detrimental effects of wear and compaction caused by concentrated foot
traffic and equipment. Ultimately, compaction affects turf grass growth, quality, and vigor.
Shoot densities of perennial ryegrass (Lolium perenne L.) and Kentucky bluegrass (Poa
pratensis L.) decrease under compaction stress (O’Neil and Carrow, 1982; O’Neil and
Carrow, 1983). Clipping yields and root growth also suffer under compaction stress (Sills
and Carrow, 1982; Carrow, 1980). Physical resistance to root penetration in compacted
soils restricts most rooting patterns to the surface soil where they are more exposed to
environmental stresses. Eventually, the compromised root system leads to reduced quality .
or a limited ability to recover from stress (Sills and Carrow, 1982).

Impact absorption affects both playability and safety of an athletic field (Rogers and
Waddingon, 1986). A wide range of surface conditions in recreational turfs are caused by
factors such as soil texture and structure, construction methods, grass conditions,
maintenance practices, and use levels. Variation in surface characteristics can lead to
differenteffects on player performance in all sports and on the behavior of balls in sports
such as golf, soccer, and baseball (Rogers and Waddington 1990a).

The Clegg soil impact tester (CIT) has been developed as a quick measure of impact
absorption, or hardness, of a turf grass surface (Clegg, 1976). Developed in western
Australia for testing dirt road surfaces by Baden Clegg, the CIT consists of a weight (4.5
kg missile) attached to a piezoelectric accelerometer, a device which measures how fast an
object speeds up or slows down (Rogers and Waddington, 1990a). Upon impact with a
surface, the accelerometer sends a signal (voltages or charges generated in disks or crystals
in the accelerometer) corresponding to negative acceleration or g (acceleration due to

gravity). The energy created during the fall is partly absorbed by the surface or is returned

49

to the missile. A higher amount of energy returned to the missile corresponds to a faster
deceleration and a higher voltage signal from the accelerometer.

Soil and plant conditions can be rated. However, the importance of these
agronomic factors is more clearly recognized when they are related to a quantitative
measurementof impact characteristics (Rogers and Waddington, 1990a). When the soil is
compacted, the surface absorbs less impact energy and peak deceleration values increase
(Rogers and Waddington, 1990b; Holmes and Bell, 1987).

Aeration of compacted turf sites using hollow tine cultivation (HT C) has been
shown to have a positive effect on lowering peak deceleration values (Rogers et al., 1989).
Athletic fields which had received aeration treatments in the past were reported to have
lower bulk densities and lower impact values.

In an effort to alleviate soil compaction on high use turf sites, cultivation is often .
employed by turf managers. One frequently used method of cultivation is core cultivation,
or hollow tine cultivation, which involves the removal of soil cores from established turf to
alleviate problems caused by soil surface compaction, layering, and thatch accumulation.
This can be very stressful on turf, is a time-consuming process, and is traditionally
performed on golf courses in the spring or fall when weather stress and traffic are lower
(Bishop, 1990).

High pressure water injection cultivation was introduced by the Toro Company,
Minneapolis, MN, as a method to cultivate turf while minimizing playing surface
disturbance (Murphy, 1990). This cultivation tool is called the Hydroject 3000‘“. In
contrast to hollow tine cultivation, water injection offers the potential for routine cultivation
during periods of high site usage and environmental stresses (Vavrek, 1992).

Water injection, shown to have many beneficial effects on soil physical properties,
is a cultivation technique employed by some golf course superintendents. Water injection
cultivationincreases large macrOpores compared to untreated turf, and is equal or superior

to hollow tine cultivation in improving bulk density, porosity, and saturated hydraulic

50

conductivity (Murphy, 1990). There is no effect of WIC on clipping yield, rooting, and
stand density, while turf treated with hollow tine cultivation exhibits lower clipping yields,
in addition to a rooting and stand density decrease .

The effects of both WIC and HTC dissipate over time, especially on high traffic
sites. Following cultivation, the soil gradually settles back into place and continued traffic
recompacts the soil (Murphy and Rieke, 1990). This demonstrates the need for a regular
cultivation program on turf in these situations. Little research has been performed in regard
to a regular cultivation program using WIC on high traffic sites. Murphy and Rieke (1992)
showed WIC to lower peak deceleration values (gmax) with the Clegg soil impact tester by
up to 23% on a practice putting green immediately following treatment. They pointed out
however, that the response lasted less than 2 weeks in duration. The objectives of this
research were to conduct a frequent, regular water injection cultivation program on high-
traffic sites and determine the effect this program has on turf quality and impact absorption

values (gmax).

W

The study was conducted at two different sites on the campus of Michigan State
University. The first site was a practice putting green at the Forest Akers East golf course.
The site consisted of a mixed stand of several creeping bentgrasses (Agrostis palustris
Huds.) and annual bluegrass (Poa annua L. var. reptans) grown on a loamy sand soil
containing 79.3% sand, 13.0% silt, and 7.7% clay with 4.5% organic matter. The green
was maintained at a height of 4 mm. Topdressing was applied 2 times in 1992 and 3 times
in 1993. Nitrogen was applied at 24.5 g N/m2 in both 1992 and 1993. The study was
initiated Jun., 1992.

Cultivation treatments at the Forest Akers site consisted of : (i) control; (ii) monthly
application of high pressure water injection; and (iii) water injection cultivation applied

every two weeks. Treatments were arranged in a randomized complete block design with

51

four replications. Treatments in 1992 were applied from 29 Jun. to 24 Aug. and in 1993,
from 10 Jun. to 24 Sep. Treatment (ii) was applied 3 times in 1992 and 4 times in 1993.
Treatment (iii) was applied 5 times in 1992 and 8 times in 1993. Water injection treatments
were applied using the Hydroject 3000‘“. Plot size was approximately 4.5 by 1.5 meters.
Water was injected to an average depth of 110 mm at 21 MPa through 1.2 mm orifices.
Nozzles on the unit were 76 mm apart and injection holes were spaced 75 mm apart.
Average spacing of the injection holes was approximately 75 by 75 mm on all dates
treatments were performed.

Turfgrass quality was evaluated on a scale from 1 to 9 with 1 being brown, 5
minimum acceptable, and9excellent. Monthly ratings were taken in both 1992 and 1993
from mid- May to mid-September.

Surface hardness was evaluated using the Clegg soil impact tester (Clegg, 1976).
A 2.25 kg hammer, or missile, was dropped from a height of 60 cm (Rogers and
Waddington, 1990a). Five measurements at different locations within the plot were taken
on each plot on each date. Readings were recorded as peak deceleration (gmax) of the
missile. At the time of taking the surface hardness measurements, 3 soil plugs
approximately 12 cm3 each were taken from each plot and combined into a representative
sample for each replication to determine gravimetric moisture content of the soil. On dates
cultivation treatments were applied, soil moisture samples were taken both before and after
treatment. In 1992 surface hardness readings taken on 14 separate dates which began 8
Jul. were taken at three to four day intervals until 24 Aug. In 1993 surface hardness
readings taken on 26 different dates were taken at three to eight day intervals from 10 Jun.
to 24 Sep.

Stimpmeter readings were taken using a USGA stimpmeter (Radko, 1980), and
were evaluated before and after each cultivation treatment in 1993. On each plot, 3
readings in both lengthwise directions were taken for a total of 6 readings per plot.

Stimpmeter readings were taken on five separate dates in 1993.

52

The second site was Beal Horticultural Gardens, a public garden which receives
intensive foot traffic and is located near the library. This site was divided into two
sections, the first being a native sandy loam soil containing 60.6% sand, 21.3% silt, and
18.1% clay with 4.0% organic matter. The second was a modified soil consisting of
approximately 10cm of a loamy sand soil overlying approximately 30 cm of coarse sand.
This surface soil was originally the native soil described above, but in the process of soil
modification the texture was changed to a loamy sand containing 79.9% sand, 11.0% silt,
and 9.1% clay with 3.2% organic matter. Both sections consisted of a mix of Kentucky
bluegrass, perennial ryegrass, and annual bluegrass, with small amounts of bermudagrass
(Cynodon dactylon L.) and creeping bentgrass. The turf was maintained at a height of 62
mm. Adequate fertilization and irrigation were applied to prevent stress. The study was
initiated 29 Jun., 1992.

Cultivation treatments at the Beal Horticultural gardens site consisted of: (i) control ;
(ii) one pass of the water injection unit over a plot area; (iii) two passes of the water
injection unit over a plot area. Treatments (i)-(iii) were performed on the same plots in both
1992 and 1993. A fourth treatment initiated in 1993 was hollow tine cultivation.
Treatments (ii) and (iii) were applied using the Hydroject 3000‘“. Water injection
treatments in 1992 were applied3 times at 2 to 3 week intervals from 29 Jun. to 23 Aug.,
and 7 times in 1993 at 2 to 4 week intervals from 10 Jun. to 15 Sep. Plot size was
approximately3 by 1.5 meters. Hole spacing was approximately 75 by 75 mm. Hollow
tine treatments were performed 2 times in 1993 using a Jacobsen (Jacobsen division of
Textron, Inc., Racine, WI) greens aerator with 9.4 mm diameter tines on 10 Jun. and 15
Sep., 1993. Tines aerated to an average depth of 50 mm. Hole spacing was approximately
50 by 70 mm and soil cores were left on the surface of plot areas on both dates.
Treatments on both sections at Beal Gardens were arranged in a completely randomized

design with 2 replications per treatment.

53

Turfgrass quality was evaluated on a scale from 1 to 9 with 1 being brown, 5
acceptable, and9excellent. Ratings in 1992 were taken on 15 Jul., 6 Aug., and 23 Aug.
Monthly ratings in 1993 began in mid-May and were taken until mid-September.

Surface hardness was evaluated using the Clegg soil impact tester and soil moisture
was determined as described above. In 1992, surface hardness readings were taken on 12
different dates beginning 15 Jul. and were taken at 3 to 5 day intervals until 23 Aug. In
1993, surface hardness readings were taken on 27 different dates at 3 to 11 day intervals
from 10 Jun. to 24 Sep.

Hole depths were measured following water injection cultivation treatments on 29
Jun., 15 Jul., 6 Aug., and 23 Aug., 1992, and 10 Jun., 24 Jun., 23 Jul., 31 Aug., and 15
Sep., 1993. Depth was measured by placing a 2 mm diameter steel rod to the bottom of
each injection hole. Six measurements were taken from each plot on each date.
measurements were taken.

All data were subjected to analysis of variance and means were separated using

Fisher's protected LSD procedure at the 0.05 level of probability.

W
Forest Akers Site

Turf quality ratings for 1992 and 1993 are summarized in Tables 3.1 and 3.2,
respectively. Quality of turf at this site was generally acceptable, despite high traffic. No
effects were seen from water injection cultivation in terms of quality improvement or
degradation, as on only one date were there significant differences among treatments.
Ratings from 12 May, 1993 revealed slightly higher quality ratings in plots receiving the
WIC 2x monthly treatment. It should be noted that traffic patterns were inconsistent at this
site due to frequent changings of golf cup sites within the plot area. These alternating
traffic patterns may have produced variability within a treatment block, making statistical

differences among treatments less apparent.

54

Table 3.1 : Turf grass quality ratings of a creeping bentgrass / annual bluegrass putting
green. Forest Akers East Golf Course. 1992. 9 = Excellent, 5 = acceptable, 1 = brown.

 

 

 

Date
Treatment 241m 8.1m 6Aug 23_Aug 8_Sep
check 6.1 a" 6.2 a 6.5 a 6.6 a 6.6 a
HJ 1x monthly 6.0 a 6.5 a 7.0 a 6.7 a 6.2 a
HJ 2x monthly 6.2 a 6.5 a 6.5 a 7.2 a 6.9 a

 

ANumbers followed by the same letter are not significantly different at the 0.05 level of
probability using Fisher’s PLSD test.

Table 3.2 : Turf grass quality ratings of a creeping bentgrass / annual bluegrass putting
green. Forest Akers East Golf Course. 1993. 9 = Excellent, 5 = acceptable, 1 = brown.

 

 

 

Date
Treatment 12May 10.1un 8.1111 12Aug liSep
check 5.3 b" 6.5 a 6.3 a 5.5 a 5.5 a
HJ 1x monthly 5.8 ab 6.8 a 6.0 a 5.8 a 5.8 a
HJ 2x monthly 6.0 a 6.8 a 6.5 a 6.0 a 5.5 a

 

ANumbers followed by the same letter are not significantly different at the 0.05 level of
probability using Fisher’s PLSD test.

55

Clegg surface hardness readings are given in Tables 3.3 and 3.4 for 1992 and
1993, respectively. A consistent pattern was seen in both years. Surface hardness tended
to increase with decreasing soil moisture. This is consistent with data from Rogers and
Waddington (1990b). Surface hardness readings taken immediately following treatment,
on 9 of 10 dates in 1992 and 1993, revealed significantly lower gmax values in plots which
had received water injection cultivation as compared to control plots. Surface hardness
readings taken immediately following treatment with water injection cultivation were an
average of 14.5% lower than those taken immediately preceding treatment. This shows
water injection lowered surface hardness values.

It may be argued that this could have been a result of increased soil moisture from
water injection. Field calibration of the Hydroject at the particular hole spacing used
showed an average injection of 17.5 liters per square meter. The addition of this water to
the water already present in the soil may have affected soil moisture. As a result, soil
hardness values may have been affected. Soil moisture for each individual plot was not
measured directly in this study, as only an average soil moisture content for each replication
was taken (three 12 cm3 soil plugs from each plot combined into a representative sample).
Average soil moisture values did in fact increase after WIC treatments on 8 of 9 dates in
1992 and 1993. These increases ranged from 0.2 to 0.8%, averaging 0.4%. Therefore,
soil moisture content is likely increased by water injection and the lowered surface hardness
values seen are possibly a combination of this and loosening of soil from the penetrating
action of the water injection jets. However, since lowered surface hardness values from
water injection frequently lasted several days, the majority of the effect is most likely due to
loosening of soil. Differences in soil moisture would most likely not last and would reach
equilibrium in a short period of time. The trend of lowered surface hardness after treatment
can be easily seen in Figures 3.1 (1992) and 3.2 (1993). On only one date (22 Jul., 1992)

were significant differences in surface hardness found among treatments immediately

56

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preceding treatment, showing lowered surface hardness due to water injection cultivation
dissipated after several days.

Stimpmeter readings taken prior to and following water injection cultivation
treatments in 1993 are given in Table 3.5. As with surface hardness, treatment with water
injection cultivation produced a significant effect on stimpmeter readings. On all dates,
stimpmeter readings taken immediately following treatment revealed significantly higher
values in plots which had received water injection cultivation as compared to control plots.
On no dates were differences among treatments evident prior to treatment. This increase in
stimpmeter readings is likely caused by a rolling or smoothing effect from the Hydroject
machine passing over the plot area. Duration of this effect was not tested in this study, but

it did not last the 2 to 3 week interval between treatments.

Beal Gardens Site

Turf quality ratings for both native and modified soils are summarized in Tables 3.6
(1992) and 3.7 (1993). As at the Forest Akers site, the turf received a high amount of
traffic. Quality ratings taken on turf grown on the native soil were generally 1 to 2 rating
points higher than those taken on turf grown on the modified soil. On no dates on either
soil, however, were differences in quality among treatments apparent.

Data for depth of water injection channels following treatment is given in Tables 3.8
and 3.9 for 1992 and 1993, respectively. Injection channels in the native soil were an
average of 4.5 cm longer than those seen in the modified soil. On all dates in both soils,
injection channels in plots receiving 2 passes of water injection cultivation were
significantly longer than those in plots receiving only one pass of water injection
cultivation. Apparently, theinitial pass provided enough of a loosening effect on the soil,
such that water injection jets in the second pass over the plot area penetrated the soil to a
deeper depth. Two passes of water injection produced an average channel length increase

of 5.0 centimeters in the native soil and 5.1 centimeters in the modified soil. This increased

Table 3.5. Stimpmeter readings before and after water injection treatment.
Forest Akers East Golf Course practice green. 1993.

61

 

11413—8

Check
HJ 1x monthly"
HJ 2x monthly"

.lulyli

Check
[-11 1x monthly
I-U 2x monthly"

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Check
I-IJ 1x monthly"
HJ 2x monthly"

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Check
HJ 1x monthly
HJ 2x monthly'

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Check
I-IJ 1x monthly'
I-U 2x monthly“

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before after
2.13 aA 2.16 b
2.07 a 2.53 a
2.04 a 2.55 a
2.30 a 2.25 b
2.28 a 2.29 b
2.31 a 2.77 a
2.50 a 2.60 b
2.54 a 2.93 a
2.60 a 2.90 a
2.22 a 2.22 b
2.25 a 2.25 b
2.20 a 2.74 a
2.07 a 2.07 b
2.05 a 2.59 a
2.04 a 2.68 a

1.4
22.2
25.0

19.9

4.0
15.3
11.5

24.5

26.3
31.3

 

* Water injection cultivation treatment performed

A Numbers followed by the same letter are not significantly different at the 0.05 level of

probability using Fisher’s PLSD test.

Table 3.6 Turf grass Quality Ratings Beal Gardens. 1992. 9=Excellent, 5=acceptable,

62

 

l=brown turf.

M Date

Treatment 15.1111 6Aug 23_Aug
Check 6.2 a" 6.2 a 6.0 a
HJ 1x pass 6.7 a 6.2 a 6.2 a
H] 2x pass 6.5 a 6.0 a 6.2 a
W

Treatment

Check 4.0 a 4.5 a 4.0 a
H] 1x pass 4.0 a 4.5a 4.0 a
H] 2x pass 4.0 a 4.5 a 4.0 a

 

 

 

" Numbers followed by the same letter are not significantly different at the 0.05 level of

probability using Fisher’s PLSD test.

63

Table 3.7. Turf grass Quality Ratings Beal Gardens. 1993. 9=excellent, 5=acceptable,

 

 

1=brown turf.

M Date

Treatment liMay 10_.Iun 12Llul 12Aug 9_Sep
Check 5.5 a" 6.0 a 6.5 a 6.5 a 6.0 a
HJ 1x pass 5.5 a 6.0 a 6.5 a 7.0 a 6.5 a
H] 2x pass 5.0 a 6.0 a 6.5 a 6.5 a 6.5 a
HTC * 6.0 a 6.0 a 6.5 a 6.0 a
W

Treatment

Check 4.0 a 5.0 a 5.5 a 4.5 a 4.5 a
HJ 1x pass 4.5 a 5.0 a 6.0 a 5.5 a 4.5 a
HJ 2x pass 5.0 a 5.0 a 6.0 a 5.5 a 5.0 a
HTC * 5.0 a 5.5 a 5.0 a 4.5 a

 

 

* Hollow tine treatment initiated 10 Jun., 1993

" Numbers followed by the same letter are not significantly different at the 0.05 level of

probability using Fisher’s PLSD test.

64

Table 3.8 Depth of injection holes following Hydroject treatment. Beal Gardens. 1992.

 

 

 

mm Hole depth, centimeters

Treatment 29_.1un 15.1111 6Aug 23_Aug
I-U 1x pass 105" 14.3 13.0 12.0
HJ 2x pass 14.5 20.3 17.3 18.0
Significance * * * *
Modified.“

Treatment

[-11 1x pass 7.8 9.5 7.5 7.5
H] 2x pass 11.5 16.8 12.0 12.5
Significance * * * *

 

A Significance was tested at the 0.05 level of probability using Fisher's PLSD test.

65

Table 3.9. Depth of injection holes following Hydroject treatment. Beal Gardens. 1993.

 

Hole depth, centimeters

 

 

NatlIeLSnil

Treatment 1.0_.1un
HJ lx pass 10.3A
I-IJ 2x pass 14.0
Significance *
Mndlfledjnil

Treatment

[-11 1x pass 8.5
11.1 2x pass 12.5
Significance "

Zilnn 23.11.11 3_LAng
12.0 12.5 11.0
17.0 16.5 15.5
3 * *
8.5 8.8 8.0

13.5 12.0 13.0
* * *

10.3
17.5
8

8.8
17.5

 

A Significance was tested at the 0.05 level of probability using Fisher's PLSD test.

66

channel depth with two passes of water injection cultivation is important, as on some
highly compacted sites, one pass of water injection cultivation may not be providing
adequate compaction relief due to lack of sufficient penetration of water injection jets into
the soil. Several passes of water injection on these sites may ultimately be necessary to
reach a desired depth. The effect this practice may have on soil structure is not known,
however, and was not investigated in this study. There was, however, no apparent loss in
turf quality after 18 passes in two years for the 2x pass treatment.

Clegg surface hardness readings for the native soil are given in Tables 3.10 (1992)
and 3.11 (1993). Data is summarized in Figures 3.3 and 3.4 for 1992 and 1993,
respectively. Unlike data obtained at the Forest Akers site, results were inconsistent.
Surface hardness readings taken on plots immediately following treatment with 1 pass of
water injection cultivation were an average of only 7.1% lower than those taken-
immediately preceding treatment. On three dates, out of a total of eight measurements (24
Jun., 8 Jul., and 5 Aug., 1993), little or no difference was seen between readings taken
prior to and readings taken following treatment with one pass of water injection. Soil
moisture was increased following WIC cultivation on S of 8 dates in 1992 and 1993, with
increases ranging from 0.1 to 0.6% averaging 0.35% . On dates where differences in soil
hardness were seen between readings taken before and readings taken after treatment, this
increased soil moisture may be playing a role in the lowering of surface hardness values.
However, soil moisture in this soil was fairly high, with an average of 31.7% soil moisture
in 1992 and 1993. Due to this high soil moisture, surface hardness readings may have
been lowered to the point where treatment with water injection cultivation produced little
effect on surface hardness.

Overall, Clegg readings were fairly consistent with the exception of the period from
30 Jul. to 12 Aug. A power outage caused damage to the irrigation system and no
supplemental irrigation was applied. Soil moisture values decreased, and surface hardness

values rose to higher than normal levels. Except for this two week period, surface

67

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71

hardness readings were generally lower and soil moisture values were generally higher than
those found at the Forest Akers site, perhaps due to more frequent irrigation. This also
may have been due to differences in soil texture, as the Forest Akers soil contained more
sand and may have been more subject to compaction.

Surface hardness readings taken following hollow tine cultivation were an average
of 19.5% lower than those taken immediately preceding treatment. Lowered surface
hardness due to both forms of cultivation dissipated over time, however, as was seen at the
Forest Akers site. Analysis of surface hardness immediately preceding treatment showed
that on only one date (6 Aug., 1992) were significantly lower surface hardness readings
found in plots receiving water injection cultivation compared to control plots. Immediately
following treatment with hollow tine cultivation on 10 Jun., 1993, lower surface hardness
readings were seen compared to control plots. By 24 Jun., 1993, differences in surface-
hardness between these two treatments were no longer evident.

Clegg surface hardness readings for the modified soil are given in Tables 3.12
(1992) and 3.13 (1993). Data is summarized in Figures 3.5 and 3.6 for 1992 and 1993,
respectively. Surface hardness readings takenimmediately following treatment with 1 pass
of water injection cultivation were an average of 20% lower than surface hardness readings
taken immediately preceding treatment and those taken immediately following treatment
with 2 passes of water injection cultivation were an average of 19.1% lower. These were
averages of 1992 and 1993 data combined. Surface hardness readings were generally
higher and soil moisture values were generally lower (22.8% average in modified vs.
31.7% average in native) than those found in the native soil. In the process of soil
modification, some of the underlying sand was apparently mixed with the native soil and
soil texture was changed to a loamy sand. This explains the lower soil moisture readings
seen, as well as the higher average surface hardness readings. As with both the Forest
Akers and Beal Gardens native soil site, soil moisture was frequently increased following

treatment with water injection cultivation (7 of 8 dates in 1992 and 1993). These increases

72

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76

ranged from 0.1 to 0.8%, averaging 0.4%. Again, it can be stated that this increase in soil
moisture may be from WIC treatment, and may be partly responsible for the lowered
surface hardness values following treatment. However, since lowered surface hardness
values from water injection frequently lasted several days, the majority of the effect is most
likely due to loosening of soil from the penetrating action of the water jets.

Surface hardness readings taken following hollow tine cultivation were an average
of 32.5% lower than those taken immediately preceding treatment. Lowered surface
hardness due to both forms of cultivation did dissipate over time, as was seen at the Forest
Akers site and on the native soil. On this modified soil, however, the dissipation time was
generally longer, especially with hollow tine cultivation. Immediately following treatment
with hollow tine cultivation on 10 Jun., 1993 (Table 3.13), lower surface hardness values
were seen compared to control plots. This difference between these two treatments
persisted until 3 Aug., a period of almost 2 months.

Analysis of surface hardness readings immediately preceding treatment showed that
on several dates, significantly lower surface hardness readings were found in plots
receiving water injection cultivation compared to control plots. These differences were
more frequently found between the control and the 2 pass water injection cultivation
treatment, and were seen on 4 dates (6 Aug.,‘1992, 8 Jul., 23 Jul., 31 Aug., 1993).
Between the control and water injection cultivation 1 pass treatments, these differences
were seen on only one date (31 Aug., 1993). This gives evidence that 2 passes of water
injection over a surface prolongs the effect this cultivation technique has on lowering

surface hardness for this soil.

In summary, results of these studies show a frequent cultivation program on high
traffic sites using high pressure water injection has no detrimental effects on turf quality.
Quality ratings of control turf were equal to those of turf receiving water injection

cultivation throughout the study. Water injection cultivation consistently lowered Clegg

77

surface hardness readings. Among the three sites, soil moisture was seen to increase
following treatment with WIC on 80% of treatment dates. This may be evidence that the
lowered surface hardness values seen following treatment are due to a combination of
increased soil moisture and loosening of soil from the penetration action of the water
injection jets. Soil moisture readings in this study were averages taken across all plots for
each replication. However, based on the rate of water application (17 liters/m2) at the hole
spacing used in this study, the calculated increase in soil moisture for each plot area was
small. These increases ranged from 0.5% on the Forest Akers soil to 1.0% with 2 passes
over the plot area on the Beal Gardens modified soil. It is difficult to say how much of the
phenomenon of lowered surface hardness from water injection cultivation is due to
increased soil moisture and how much is due to loosening of the soil.

Hollow tine cultivation also lowered surface hardness readings. The effect that”
these cultivation techniques had on lowering surface hardness, however, dissipated over
time, although the duration of this effect was variable among the three soils. Relief of
compaction resulted in lowered surface hardness, but this relief was limited in duration due
to rapid recompacting of the soil. Differences in surface hardness between control plots
and plots receiving water injection cultivation which were seen immediately following
treatment on most occasions did not last the 2 week time period between water injection
treatments. Surface hardness is only one parameter, however, and other meaningful tests
such as bulk density, porosity, and hydraulic conductivity were not measured in this study.
Regular cultivation is needed on high traffic sites. Water injection is a method of
cultivation thatcan be frequently applied on high traffic sites, especially highly compacted
portions of an athletic field or golf green. Water injection cultivation provides short term
relief of compaction, while imparting minimal stress to the turf plant and playing surface.
The ability to lower surface hardness with WIC could be an important tool for athletic turf
managers in need of a way to decrease surface hardness without adding water to a field or

core cultivating.

78

Referencesjllted

Bishop, D.M. 1990. Water injection: The agronomic impact. Golf Course Management.
58(3): 42-44.

Carrow, RN. 1980. Influence of soil compaction on three turf grass species. A gron. J. 72:
1038-1042.

Clegg, B. 1976. An impact testing device for in situ base course evaluation. Aus. Rd. Res.
Bur. Proc. 8: 1-5.

Holmes, G., and M.J. Bell. 1987. Standards of playing quality for natural turf. The Sports
Turf Research Institute. Bingley, West Yorkshire, England.

Murphy, J .A. 1990. The influence of cultivation on soil properties and turf grass growth.
Ph.D. Diss. Michigan State Univ., East Lansing.

Murphy, J.A., and RE. Rieke. 1990. Comparing aerification techniques. Grounds
Maintenence. 25(7): 10- 12, 76-79.

Murphy, J.A., and PE. Rieke. 1992. Evaluating additional management uses for high
pressure water injection. In Agronomy abstracts. ASA, Madison, WI. p. 174.

O’Neil, K.J., and RN. Carrow. 1982. Kentucky bluegrass growth and water use under
different soil compaction and irrigation regimes. A gron. J. 74: 933-936.

O’Neil, K.J., and RN. Carrow. 1983. Perennial ryegrass growth, water use, and soil
aeration status under soil compaction. A gron J. 75: 177- 180.

Radko, A.M. The U.S.G.A. Stimpmeter for measuring the speed of putting greens. p.
473-476. In J.B. Beard (ed.) Proc. 3rd Int. Turf grass Res. Conf., Munich,
Germany. 11-13 July 1977. Int. Turf grass Soc., and ASA, CSSA, and SSSA,
Madison, WI.

Rogers, J.N. III, and D.V. Waddington. 1986. Impact absorption measurements with
portable equipment. In Agronomy abstracts. ASA, Madison, WI. p. 138.

Rogers, J.N. III, and D.V. Waddington. 1990a. Portable apparatus for assessing impact
characteristics of athletic field surfaces. p. 96-110. In R.C. Schmidt, E.F. Hoemer,
E.M.Milner, and CA. Morehouse (eds). Natural and artificial playing fields:
Characteistics and safety features. American Society for Testing and Materials.
Philadelphia, PA.

Rogers, J. N. 111, and D. V. Waddington. 1990b. Effects of management practices on
impact absorption and sheer resistance in natural turf. p. 136-146. In R. C.
Schmidt, E. F. Hoemer, E. M. Milner, and C. A. Morehouse (eds. ). Natural and
artificial playing fields: Characteistics and safety features. American Society for
Testing and Materials. Philadelphia, PA.

 

Rogers, J.N. III, D.V. Waddington, and JG Harper. 1989. Athletic field hardness and
traction. North Carolina Turf grass. 7(2): 27-31.

79

Sills M.J., and RN. Carrow. 1982. Soil compaction effects on nitrogen use in tall fescue.
J. Am. Soc. Hort. Sci. 107(5): 934-937.

Vavrek, RC. 1992. Aeration: needed more today than ever before. USGA Green Section
Record. 30(2): 1-5.

80

APPENDIX

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