R EJU VE N ATIO N

OF AN OLE A - P L E ORCHARD BY MEANS OF

F E R T IL IZ E R S ,

MULCHES AND COVER CROPS

By
Fr ank N, Hevretson

A THESIS
Su b m i t t e d to the School of Graduate
State College of Agricu lt ur e
in partial

fulfillment

Studies of M i c h i g a n

and A p p l i e d Science

of the r e q u i r e m e n t s

for the degree of

DOCTOR OF PH ILOSOPHY

Department of H o r ti cu lt ure

1953

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ACKNOWLEDGMENTS
The author w i s h e s
F. N. F a g a n and Dr.

to express his than ks

R. D.

to P r o f e s s o r

Antho ny of the H o r t i c u l t u r e

D e p a rt me nt at P e n n s y l v a n i a State U n i v e r s i t y for their
assistanc e

in h e l p i n g to plan the e xp er im ent r e p o r t e d herein,

and to Prof.
guidance

in r e v i s i n g the e a r l y draf t of the manus cri ot;

to Dr. H.
Dr.

Frank F e r g u s o n of the same i n s t i t u t i o n for his

P. T uk ey for his e n c o u r a g e m e n t and council

A. L. K e n w o r t h y for his

valuable sug ge sti ons

and to

t h r o ug ho ut

the w r i ti ng of the ma nus crip t*
Thanks

are also due

to the mem bers of the Penn s y l v a n i a

State U n i v e r s i t y Fruit R e s ea rc h L a b o r a t o r y 3taff at Ar e n d t s ville,

Pa.

for their assist anc e in o b t a in ing the great ma s s

of re cor ds in v o l v e d in this study,

and e s p e c i a l l y to Dr.

J e a n E. H a w k s H e w e t s o n for h e r u n t i r i n g a ss istan ce wi t h
the l a b o r a t o r y analyses.
To Mr.

Ra lph Tyson,

in this study,

p r es en t owner of the o r c h a r d us e d

is due a special note of a p p r e c i a t i o n f o r

hi3 c o o p e r a t i o n and inte res t in the experiment.
The au t h o r also wis he s to thank D r s • R. L. Cook,
the De partme nt of Soils,

G.

P. S t e i n b a u e r of the D ep artme nt

of Bo t a n y and Plant Pathology,
Representative

C. R. Megee,

Grad ua te Council

and H. B. T u k e y and A. L. K e n w o r t h y of the

D ep ar tment of H o r t i c u l t u r e for
committee*

of

serving on his guidance

R EJUVE NATIO N 0 ^

AC OLD A ^ L E

F E R T IL IZ E R S ,

MULCHES

ORCHARD BY MEANS OF

AND COVER CxROn S

By
Frank N. H e w e t s o n

AM ABSTRACT
S u b m i t t e d to the School of Gr ad ua te Studi es of M i c h i g a n
State College of Agri cul ture
in partial

and Ap pl ied Science

fulfillment of the re qu ire men ts
for the degree of

DOC TOR OF PHI LOSOPHY

Department

of liorti culture
1953

A p p r o v e d ___________ J£'<

P ra nk N. H e w e t s o n

T r e a t m e n t s w h i c h we re

d e s i g n e d to re ju ve n a t e

apple o r c h a r d i n c l u d e d the use of three
applica ti on s
and La d i n o

and b l u e g r a s s

co v e r crop plots.

I n the laboratory,

slots

Results we r e

of shoot growth,

and yield of the trees,

cover crops*

rates of f e r t i l i z e r

c o m b i n e d w i t h straw and pea vine m u l c h

re c o r d e d in the field by means
cumf er en ce

an old

trunk c i r ­

and by we i g h t s

dr y weight,

of the

chl orop hy ll

and

n i t r o g e n content, of the leaves wer e determined.
The h i g h e r f e r t i l i z e r ap pl ic atio ns wer e effec ti ve
In c r easing trunk area,

co ver crop weights,

n i t r o g e n and c h l o r o p h y l l
and f i n a l l y yield,

in

leaf weight,

content of the leaves,

shoot g ro wth

in that rel at iv e order.

The effects on gro wth wer e In p r o p o r t i o n to the amounts
of f e r t i l i z e r used.
The increase
phyll

in leaf weight,

leaf n i t r o g e n and ch l o r o ­

s t i m ul at ed tree growth which In turn i n c r ea se d yield.
A m o n g the m u l c h and cover crop treatments,

were o u t s t a n d i n g in their benef ici al
formance,

nea vines

effect on tree p e r ­

This effect was more apparent in the low

than in

the m ed iu m or h i g h f e r ti lity plots,
A p r o g r a m of r e j u v e n a t i o n as c o n d u c t e d under the c o n ­
ditions of this experiment,
benefits.
removal

wo ul d give

Ov e r a lo n g pe r i o d of time,

t e m p ora ry ec on om ic
however,

a tree

and re pl an t i n g p r og ram mi ght be more profitab le.

j. j. i

TALLE

0 ' ;‘ CONTENTS
Ti

-i

^

>jrpon .yrrtmx 'a jr

REEL

* • „ * * * * .

1

OF LI^ERATORE . .......

EXPERIMENTAL PROCEDURE .......

3
***■«•••#»«

PIo b Layout anu Anpiic 11!o;■ <:
Me tiio'ls of Detaining Data . .

#

c
n

» * J m m » p *

14*

-L^1.X+

«

■

«

*

-

•

*

19
Cover Crop heights * .......

av

Tree Growth .............. ♦ «

22

Shoot growth.

22
28

Loaf Growth and Conoc.Tltion .

32

Leaf weight, chlorophyll an , nitre ea e ' ,
in 1947 ....... * . . -

32

.’t-a /,ji, ,;lP:

Loaf weight, ehl oronhy11 an
in 1949 ..............

38

Leaf weight . . . . . . .

38

Chlorophyll . . ....... .

43

Nitrogen. . . . . . . . .

47

Correlations totn/een leaf wei,- .t, Ciilcr*.- .*yll
and nitrogen.
, .

54
56

Yield ....................
ECONOMIC A?PLICAT10K .........

V

DISCUSSION.................

««

4

«

•

*

«

•

•

*

«

«

+

• • * * • • * »

61
65

S U M M A R Y .............. .. ...........

73

LITERATURE CITED . . .

74

.......

LI S T OS FI GUR ES

figure
1
2
3

4
5

6

?af-e
Typical tree when experiment was started.

2

Weight of two cuttings of cover c rops :n e•ieI•
.
year in relation to fertility levels end
years of sampling . . . . . . ............ ..

21

Relative shoot growth as influenced by
fertility levels and groundcovers.

9

10

11

27

Percentage increase in trunk cross section
area in relation to fertility levels and
ground c o v e r s , . ............................

33

Leaf analyses in 191-17 as measured by dry
weight, chlorophyll and total nitrogen
respect to f er ti li ty levels and

ground c o v e r s ...................... ..

8

6

Diagram
tree nlanting end. experimental
plots used in the rejuvenation study. . . . .

with

7

. „ „

..

35

Leaf weights during; 1949 season in re} ation
to fertility levels and groundcovers . . . *

4l

Leaf chlorophyll values during the 194Q
season in relation, to fertility levels
and ground covers . ............ .

45

Total percentage nitrogen in dried leaves
during the 1949 season as Influenced by
fertility levels and groundcovers. . . . . .

1.9

Total nitrogen nor leaf during the 19t|9 season
as influenced by fertility levels and
ground c o v e r s ..............................

p2

Annual yield ner tree from 19^6 to 1949
according to fertility levels and ground
covers......................................

58

V

LIST Of TAfLES
Taole
I
II

III

IV

V

VT

VII

VIII

IX
X
XI

XII

XIII

P
Moan trunk clrc^riforence fop clots, a ^eas
and f ert111 f y tpeatnen ts ,
.♦ . •

10

Ccmposition of the special mixture fertilizer
and the amounts of the various ingredients
used per tree for the different fertility
levels

13

*

Weight of cover crop clippings as related to
fertilizer applications expressed ^s fresh
weight in tons pep a c r e , ....................

20

Annual linear shoot growth in relation to
fertility levels and ground covers, expressed
as centimeters per tree......................

23

Annual linear shoot growth in relation to
fertility levels and ground, covers, expressed
as percentage of the 1949- values

26

Annual trunk cros3 section area per tree,
according to the various fertilit;/ levels
and ground covers.................. ..

29

Trunk cross section area expressed as average
percentage increase per tree, according, to
the various fertilit;/ levelsand ground, covers
Leaf weight, chlorophyll and nitrogen values
for 1947 according to fertility levels and
ground covers • . • ,

31

,

34

Leaf weights in 199-9 as Influenced by fertility
levels, ground covers andtime of sampling
*• .

39

Chlorophyll values during the 1949 season as
related to fertility levels andground covers,

I4J4.

Percentage of total nitrogen in the aried leaves
during 1949 with respect to fertility levels
and ground covers........... .

4^

Milligrams of nitrogen per leaf during the 1949
season in relation to fertility levels and
ground covers.
..............

_9l

Correlation between leaf weight, chlorophyll
and nitrogen in 1949

$9

Table

XIV
XV
XVI

Annual yield per tree according to the
fertility levels and ground covers . . . . .
Annua], arices and crop value for York Imperial
apples . . . . . . . . . . . . ............
Leaf weight increase from 19‘
-j-7 to 19^-9
within the different fertility levels and
ground covers......... . . . . . . . . . .

.

INTRODUCTION
I n m a n y largo

fruit g r o w i n g sections of the co unt ry

there are old apple or ch ar ds w h i c h fail to p r od uc e
fa c t o r y yields,

satis­

altho ug h the m a j o r i t y of the m are s i t uated

in go o d lo cations and c o n t a i n m a r k et ab le varieties.

Their

low p r o d uc tive ca p a c i t y m a y have be en caused oy low soil
fertility,

p o o r physic al

condit io n of the soil,

or ne gl ec t

of the trees themselves.
The owners of these orchards are fa c e d wit h the p r o bl em
of de ci ding w h e t h e r to take out all of the old trees and
replant the whole l o c a t i o n or to give the old trees special
treatm ent s in or der to restore the ir vigor a nd thu3 increas e
their fruit

production.

The y mu st first decide w h e t h e r the

co n d i t i o n of the trees will respond to a r e j u v e n a t i o n p r o g r a m
and,

then,

they must c o n si de r the cost of this pr o c e d u r e in

r e l a t i o n to the cost of r e p l a n t i n g and the loss of income
until the trees come into bearing.
I n any attempt to im pro ve yields,
to produce h e a l t h y vigorous trees.
and there must be an adequate
Insects and diseases.

it is first n e c e s s a r y

The trees m u s t be p r u n e d

spray pro gram to control

The ph ysi cal co n d i t i o n and nu t ri en t

level of the soil mu st be suitable for o p t i m u m tree p e r ­
formance •

The pr ese nt

i n v e s t i g a t i o n was de si gn ed to re ju ven ate

an old apple o r c h a r d by im p r o v i n g the c o n d ition of the
w i t h the use of various mulches,
trea tm en ts and at the
of the

trees.

The

co ver crops and f e r t i l i z e r

same time to m a i n t a i n the o t h e r needs

first pu rpo se was to find out to wh a t

extent c ov er croos and fe rti lizers wo uld increa se tree
vigor and crop produc tio n*

The

second purpo se wa s to

d et ermine if these tre atments w e r e
advi s a b l e ,

soil

f i n a n c i a l l y soun d or

REV IE W OF L I T E R A T U R E
W i t h the d e v e l o p m e n t of the fruit

gr owi ng in d u s t r y

in the U n i t e d States and in other countries,

many older

orchards of this e arly pe r i o d began to decline
and production*

Thus m a n y farmers and i n v es ti ga to rs

i n t e r e s t e d in r e j u v e n a t i o n programs*

Ballo u

d e s c r i b e d the p o o r conditions of or cha rds
ea rly 1900* s,

in vigor

and re p o r t e d on the benefits

(3,

were
5)

in Ohio in the
that he o b t a i n e d

from u s i n g correct sprays and va riou s co mbin at io ns of
fertili z e r s ,
I n reality,

re n o v a t i o n and good o r c h a r d m a n a g e m e n t

p r a c ti ce s do not diff er greatly.

A c c o r d i n g to G ould

these p r a ct ic es si m p l y repre sen t diffe rences

(16)

in the objects

to be o b t a i n e d and the m a n n e r in wh i c h the de ta il s are
c a rri ed out;

r e n o v a t i o n is a more

trated procedure,

strenuous and mo r e c o n c e n ­

b u t it involves the same or ch ar d m a n a g e ­

ment op er atio ns su ch as tillage or some substitute,
lizing,

ferti­

p r uni ng an d insect and disease control.

M a n y ’’p o p u l a r ” or n semi - p o p u l a r ” articles and bul l et in s

(1, 6, 7, 8, 10, 11, 12, 13, 11+, 15, 18, 19, 20, 21, 22, 23,
2I|., 25) have be e n w r i t t e n on the
rejuvenation.
observations

subject of apple o r c h a r d

Some of these p u b li ca ti ons r e p o r t e d g r o w e r
and gave d e t a i l e d programs to

co n d i t i o n of the trees,

improve the

others r e p o r t e d ex p e r i m e n t a l projects,

but non e of the art icles gave adequate ev id ence

to s u b s t a n ­

tiate the r e c o m m e n d a t i o n s .

authors

agreed,

however,

The ma jo ri ty of the

that the trees did not r e s p o n d to trea tm ent

if they w e r e very old or If t hei r v i t a l i t y ha d been r e d u c e d
by neglect,

pest s or diseases.

T h e y also b e l i e v e d that no

p r o g r a m wa s f i n a n c i a l l y a dvi sable unl ess the trees were
l o c a t e d in a good sit ua tion as to air drainage,
climate and unless the v a r i e t y was marketab le*

soil and

EXPERIMENTAL
Plot L a yo ut

PRO CE DU RE

and A p p l i c a t i o n of M a t e r i a l s

The o r c h a r d se le ct ed for the current s tu dy was l o c a t e d
on the Cu mb e r l a n d - A d a m s

coun ty line,

in south central Penns;;-!vanla.
1908,

just n or th of Id a v i l l e

The o r char d was p l a n t e d in

and ha d not b e e n c u l t i v a t e d for a num ber of years

pr i o r to 191+6,

the date w h e n this ex pe rime nt was started.

The c o n d i t i o n of the trees was very poor,
of m a n y in the area.
cu t t i n g out.

Terminal

al t h o u g h typical

N u m e ro us limbs w e r e dead and n e e d e d
growth was in m a n y cases negligible.

F o lia ge wa s light and the leaves w e r e small and po o r In
color.

The trees shown in Figure 1 are ch ar acte ri st ic of

this con dition.
The or c h a r d site was excellent

for air drainage.

It

wa3 situate d at an e l e v a t i o n of 1100 feet and o v e r l o o k e d
m o s t of the su rro un din g country.

Th ere was a gradual

slope

in the la n d from n o r t h to south and east to west.
The

soil in this o r c h a r d was typical of thst found in
1
this s e ct io n of the Blue Ridge Mountains,
It was an ashe
silt l o a m d e rive d from m e t a m o r p h o s e d vol can ic rock.
residual

soil was

from the m etab as al t or g r e e nsto ne

1. Soil de s c r i p t i o n m ad e by R. C. Long,
tion Service, Gettysburg, Pa.

The
and

Soil C o n s e r v a ­

Typical tree vr'aen expo ri merit was started.

epidote rock.

This geo logical

stratum of basic rook h a d been

b roke n into small fr ag me nts w h i c h for med a m o d e r a t e l y deep
soil of good structure.
loam, wa s

The texture,

that of a m e d i u m silt

such that it er o d e d at on l y a m o d e r a t e level.

The available m o i s t u r e h o l d i n g ca p a c i t y was high.
well drained.
stratum,

The p e r m e a b i l i t y of the subsoil

or par en t material,

s li ght ly acid,

was mod erate.

pH be tw een 5 and 6,

was m e d i u m to low.

It was

and the

The

sub­

soil was

and the inherent fe rt ility

Such a soil was c o n s i d e r e d to be p a r ­

ti c u l a r l y a d apte d to the culture of fruit trees.
Since there w a s a gradual
was not uniform.
h i g h e r area,

The mo re

and the less

lower corner,

slope in the orchard,

fertile
fertile

soil was in the north,
soil In the

southwest,

w he re some er osi on h a d occurred.

d i t i o n of the trees wa 3

the soil

The c o n ­

relat ed to the soil dif feren ce s to

a co nsi dera bl e extent w h i c h was taken into c o n s i d e r a t i o n
w h e n the plots were la yed out.
O r i g i n a l l y the orchard,

w h i c h covered about 13 acres,

c o n t ai ne d 570 York I m pe ri al apple trees.
31 x 31 feet apart In 21 rows,
ta inin g 28 trees.
there we r e

At

Th ey were

set

the m a j o r i t y of the rows c o n ­

the time this study was

started,

some trees m i s s i n g and a few others ha d to be

re mov ed du r i n g

the

course of the

The plots

for

this e x p e rimen t we r e laid out a c c o r d i n g

to the d i a g r a m in Figure 2.
12 trees, wit h

the

study.

Ea c h plot c o n t a i n e d

e x c e pt ion of one,

from 9 to

wh i c h c o n t a i n e d o n l y 8*

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Diagram of tree planting
the rejuvenation study,
(See pages
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All plots
vines

were en t i r e l y s ur ro unde d by buffer trees.

and straw were u s e d as m u l c h i n g mat erials,

Ladino

clo ver

p r a t e n s i s , L,)

(T r l f o l i u m r e p e n s , L.)

these treatments,

(Poa

V/ithln ea c h of

there were three lev els of fertility.

Ea c h sub -t re a t m e n t was r e p l i c a t e d once,
2i_|_ plots,

while

and bluegras s

were u s e d as cover crops,

Pea

m a k i n g a total of

w h i c h c o n t a i n e d a lt oget he r 2I4.? trees.

There

w e r e fro m 19 to 2l± trees for each of the treatments,
II4. and 15 were u s e d for ot her purposes and were not

plots
inc lu de d

in this study.
The plot layout w a s

based,

as far as possible,

on the

size of the trees at the be gi nn in g of the experiments.
T runk c ir cu mfe ren ce me a s u r e m e n t s wer e taken ea r l y in 191+6,
be fo re
plot,

any gro wth occurred.

The average values for each

to ge th er w i t h the probab le er ro r are shown in Table I,

The data indicate that the smallest trees were lo c a t e d in
the southwest corner,

area 1,

plots 1, Jf, 7 and 10.

Trees

i n the no r t h ha lf of the orc ha rd were r e l a t i v e l y u n i f o r m in
size.

On the basis of these m e a s u r e m e n t s the o r ch ar d was

d i vid ed fr om east to west,

using the south po r t i o n as

repli cat e 1 and the no r t h as replicate 2,
Th is p l a n p e r m i t t e d r e p l i c a t i n g the t re at me nt s in such
a w a y as to counter act soil vari at io ns

as m u c h as possible.

E a c h hal f of the or c h a r d was d i vided into
for each fer t i l i z e r treatment.

three areas,

one

Plot 13 was u s e d instea d of

plot 1$ to complete area 6 so as to keep plots II4. and 15 for

TALLE I

M E A N TRHNK C I R C U M F E R E N C E EOR PLOTS,
A N D FER TI LI TY T R E A T M E N T S

Plot

AREA S

Number
of trees

average
ci reumfsrence
(cm.)

^rcuable
error

12
11
11
8
42

89*6
99.7
86.6
101 .9
92.8

8-17
2.17
3.03
1.77

1*46

12
11
10
10

111,6
106 .1
9°. 6
106.0
10A.9

2.68
2.18
2.25
2 .04
1 020

1
li
7
10
Area 1
2
5
8
11
Are a 2

43

11^.6
111.9
116.1

1.54

100.2

::.49

Area 3

10
10
o
9
38

118.0

1.11

97.1
101.9
100.1

2.33
1 .92
2.24
09-3

Area 4

10
9
10
11
40

100,6

1.20

98.6
9f’.2

1.99
2.62

Area 5

11
12
11
11
45

loo. 5
100.6
100,2

1.62
0.98

102*7

1.72

3
6
9
12

16
19
22

25

17
20
23

26

9
10
9
9

13
18
21
24
Area 6
Fertility
High
Medium
Low

area
1 and 5
3 and
2 and 6

37
87
80

103 .6

109,0

2.43

-.43

1.45

1.37

97.7

108 .1
104.4

8 •96
1.68
1.62

96 ♦6
106.6
105.2

0.90
0.94

O.87

o th er

studies.

Ta b l e 1 also

the trees In e a c h area.
the larges t values.

'rea 1 had the smallest

The

r e l a t i v e l y constant.

shows the c i r cumf er en oe of

figures

and area 3

for the ot her areas were

The hi g h f e r t i l i t y tre atm ents we re

p l a c e d in areas 1 and 5 * the average trunk cir cu mfere nc e
b e i n g 96.6 cm.,
in areas

the m e d i u m ferti lit y tre atme nt s were p l ace d

3 and 4-> the average trunk c i r cu mf er ence of w h i c h

was 106.6 cm,,

and the low f e r t il it y tr ea tmen ts we re p l a c e d

in areas 2 and 6 , h a v i n g an average trunk ci rc um fe renc e of

105.2 cm.

O n th is basis,

the pr ob ab le error was p r a c t i c a l l y

the same for e a c h f er t i l i t y level.

Nevertheless,

f e r t i l i t y tre atm ents were on the poorest plots,
advantage

to the lo we r f e r t i l i t y treatments.

cover crop tr eatments
ap pl ic a t i o n s

the hi g h

givi ng an

The m u l c h and

crossed the va ri ous fertil ize r

at right angles,

Figure 2.

The p e a vine and straw mu l c h e s were
the entire tree square,
three feet away from the

spread e ve nl y over

except that they were kept about
trunks.

Pea vines were o b t a i n e d

from a vinery and w e r e u s e d at the rate of 10 tons pe r acre*
Baled

straw wa s us e d at the rate of five tons per acre.

These rates p r o v i d e d appro xi m a t e l y the same amount of dry
m a t e r i a l per acre.

Th ese two m u l c h i n g m at e r i a l s were

ap pl ie d in 194-6* 194-7 and 194-9.
o bt ai nable in 194-8#

Pea vines were not

30 n e ithe r m u l c h wa s a d d e d in that year.

The La d i n o c l o v e r plots w e r e given p r e l i m i n a r y tre atments
p r i o r to planting,

in or der to insure sa t i s f a c t o r y growth of

this cover*

I n 194-6* these clots r e c e i v e d m a n u r e

at the

rate of five tons per acre and were s u b s e q u e n t l y seeded to
sweet clover*
and the pl ots

I n 194-7* the sweet cl o v e r was d iske d aown
se ede d to L a d i n o

pounds p e r acre.
we re

Oats,

s eed ed along with

clover at the rate of 1.5

at the rate of 32 pounds per acre,
the La d i n o

to act as a nurse crop.

The entire or c h a r d was in b l u eg ra ss w h e n the e xp er imen t
was

started.

Therefore,

this cover was

The f e r t i l i z e r treatments,
and c o v e r crop treatments,
m e d i u m and h i g h level.

already establis hed .

wh i c h c r os se d over the m u l c h

co ntained n i t r o g e n on a low,

The growe r made

an overall a p p l i ­

ca ti on of five pounds of C y a n a m i d pe r tree in the late fall
of 194-5*

The low fer t i l i t y plots had no other f e r t i l i z e r

the first year.

I n a d d i t i o n to the Cyanamid,

the m e d i u m

and hi gh f e r t i l i t y plots r e c e i v e d 18.75 and 37*5 pounds,
respectively,

of a special f e r t i l i z e r mixture,

the spring of 194-6.

ap p l i e d in

I n 194-7 and subsequent years,

was re p l a c e d b y an overall

Cyanamid

ap p l i c a t i o n of five pounds of

nitrate of soda and the special

fert il izer was I n c r e a s e d to

25 and 50 pounds p e r tree for the m e d i u m and h i g h fe r t i l i t y
plots,

respectlvely.

Lime at the rate of 1.5 tons p e r acre

was a p pl ie d to the entire or c h a r d in M a r c h 194-6*
The
Ic wa s
lizer

special f e r t i l i z e r mi xt ur e

f or m u l a t e d to give

is shown in Table II.

appr ox i m a t e l y a 10 - 10-10 f e r t i ­

for the hi gh fer t i l i t y plots,

c on s i d e r i n g the a d d i ­

tional n i t r o g e n fe r t i l i z e r applied by the grower-.

It was

i- F IA

II

c o 'iP O S iT io :: o f Tin*: s p : c i ; , l ttix t'h ip : i b i o ' T L i z i : a tjd t h e a m oun ts o f t h e
V/v RIO US 11101 ED I OUT 3 USED P E i TUFF FOP IKE D IFFE h FPT F E R T ILIT Y LiF/LLS

M a te r ia l

1936
>1

To ta l
(.lb s )

(lb s )

3 .0
24.0
3 .0

1 .2 6
0 .6 3
0 .6 0

2 0 .0

^ ro

(lb s )

K20
(lb s )

T o ta l
(lb s )

1937-39
H
P20^
(lb s )
( lo s t

k 2°
( .lb s )

S p e c ia l F i x t u r e
TJr amon
NaNOo
( N H ^ S G i^
Arnmoniated
su p e r-p h o s p h a t e
(2 .6 -2 0 -0 )
Su p•e r - p h o s p 1r i t e
KOI
Porax
xo t a 1

6 .3
6.7
3 .8
ii .0 0

v-. e
1 .0
f

j

3 7 .3

3 .0 2

> *x

0 .3 3

2 .6 3
0 .9 0
0 .7 9

U.oo

3 .9 0

26.7
p r

3 .9 0

5 o.o

5 .13
6.13

*- * y

5.13

5.13

5.13
2.9o
' */; o

5.13
2 .66

5 - 13
2, 3b

O «v'/1
C

10.27

lo .? 7

3 .3 3

O v e ra ll M a te r ia l
Cyana.nid
rlaNO^

A* -1
C

o .e

T o t a l p e r T re e
H ig h f e r t i l i t y
Fed ? u r f e r t i l i t y
Low f e r t i l i t y

P e rce nta ge
xij
c^ial
fe r tiliz e r
I n s p e c ia l p lu s
o v e ra ll
H ig h f e r t i l i t y
Medium Per t i 11 l y

i4<-. ,
2 3 .7 3
.0

3 .0 0
2 .33
,A

e .o 6

3.1 a
10.31

3 .0 0
2.00

3 .9 0
1 .9 6

!'T'

3

C

'3
m C

5.0

10.7

6 .3 1
O 1o
• »■'! e~

1 0 .3

6.13
8.21

f
<

i-\

9.33
9. 38

v . 33
3 «L1^

14

also d e s i g n e d to give
throughou t

a con ti nuo us

the g r o w i n g season by the use of d if ferent

forms of nitrogen.
kinds of ni tro gen :

Tne first year,
so diu m nitrate,

its nit rog en ;

a m m o n i u m sulfate,

at a somewhat

slower rate ; Uramon;

phosphate,
rate.

supply of n i t r o g e n

which

release

it co n t a i n e d

four

w h i c h r e ad il y rel ease s

which
and

release s

its n i t r o g e n

ammo ni ated super

their ni tr ogen at an e v e n slower

I n the sec ond and su bsequent years,

the

am mo nia ted

super p h o s p h a t e was d i s c o n t i n u e d and regular 20 per cen t
super p h o s p h a t e used,
ch emi cals

be ing ch a n g e d

ap p r o x i m a t e l y the
was added

the amount cf the ether ni tr og en ous
so that the fo r m u l a w o u l d co nta in

same total per centa ge of nitrogen.

the first year,

f o l l o w i n g years.

but wa s d i s c o n t i n u e d In the

I n the first year,

the high fer tility

plots r e c e i v e d iq.CO pounds each of n i t r o g e n and
3.90 pounds of

K o0,

anc^

and In the later years they re c e i v e d

5.13 p o un ds of each ingredient.
received. 2.1q9,

Borax

The m e d i u m fe r t i l i t y plots

2.00 and 1, 95 pounds of nitrogen,

respectively,

the first year,

and 2.96,

P o0c and

2.56 and 2.56

pounds of the

same In g r e d i e n t s in the fo ll owin g years.

low fert il it y

plots r e c e i v e d on ly n i tr og en at the rate

0.98 po u n d s the first y e a r and 0.80 pounds the

The
of

su bs equ ent

ye a r s •
M e t h o d s of O b t a i n i n g Data

The effects of the vario us f e r t il iz er app lications,

mulches

and c o v e r crop tr ea tme nts were r e c ord ed by m e a s u r i n g

the y i e l d of the cover crops and the p e rf orman ce of the
trees*

Tree p e r f o r m a n c e was m e a s u r e d in terms of lin ear

shoot growth,
Th e l a t t e r

tr unk circumference,

in cl uded leaf weight,

d e t e r mina ti on s.
to s t atist ic al

yi eld and leaf response*

n i t r o g e n and

As far as po ssi ble

chlorophyll

all data were

s ub jected

analyses.

The growth of b l u e g r a s s and L a d i n o

clover crops was

d e t e r m i n e d twice in each of the years 191+7, 191^8 and 191+9•
I n the first two years,
m e a n s of a three

a on e - y a r d square was m a r k e d off by

sided " f o r k ” ,

All grass

inside this square

was cut off at gro und level wi th a sickle and w e i g h e d in
pounds.

I n 191+9, the pr oc ed ure wa s modified.

strip on© y a r d wide wa s cut w i t h a sickle
a G r a v e l y g a r d e n tractor.

bar att ach ed to

The cut cover w a s w e i g h e d and

the results a d j u s t e d so as to be co mp arable
pr e v i o u s years.

A 31-foot

to those in

The r es ults were exp re ss ed as fresh w e i g h t

in tons pe r acre.
Shoot

growth m e a s u r e m e n t s we r e t a k e n in the late

after all terminal gro wth h a d bee n completed.
it was

possible to me as ur e

years*

Th u s the treatment

summer

I n 191+6,

this growth for the two pr e c e d i n g
responses co u l d be co m p a r e d to

the pr e v i o u s p e r f o r m a n c e of the trees.

Shoots w e r e

on the basis of their p o s i t i o n on the tree,

sel ec te d

w h i c h was

d i v i d e d into four quarters ac cor ding to the four points of
the compass.

W i t h i n each quarter,

terminals were used that

were

gr o w i n g at an angle of 45°

w h i c h h a d ma de

shown by W i l c o x

were

(27)

and side shoots and has

Thi3
oeen

to be the most rel iab le pro ce du re

type of growth.

take n on each tree,

in the

and

three years of n o n - b r a n c h i n g growth.

p r o c e d u r e e l i m i n a t e d suckers

m e a s u r i n g this

from the hor izo nt al

for

T w e n t y- fi ve m e a s u r e m e n t s

d i s t r i b u t e d as eve nly as pos si ble

four qu a r t e r s of the tree*

The av erage of these

m e a s u r e m e n t s r e p r e s e n t e d the vigo r of the tree and gave the
annual

shoot growth.

T r u n k c i r c u m f e r e n c e m e a s u r e m e n t s were ta ke n at the end
of the g r o w i n g season after the leaves had fallen and the
trees h a d complete d
ma de

trunk growth for the year.

T he y were

at a ma rk one foot above g ro und level b y mean s of a

steel tape.

Tr u n k area was c a l c ulat ed from trunk ci r c u m ­

fe re nc e m e a s u r e m e n t s .

A co mpari so n of the actual growt h

i n c r ea se s p e r y e a r d i d not give va lid results because of
in itial v a r i a t i o n in tree size.
this ori gi nal

I n orde r to compensate for

di ff ere nce in size,

the annual

increase each

y e a r was e x p r e s s e d as the pe rc enta ge of the 1945 value.
During 1 9 4 %

an intensive

du rin g the entire gr ow ing
ch lorop hyl l

study was made on the leaves

season.

Total leaf weight,

and n i t r o g e n m ea s u r e m e n t s we r e made four times

du rin g the season,

on June 7, August 1,

Se pt ember l£ and

O c t o b e r 13»
The

samples fo r ch emic al analyses we re

two r e p r e s e n t a t i v e tr ees in each plot.

co llect ed from

Se ve nty-f iv e leaves

p e r tree w e r e

s e l e c t e d from the m i d - s e c t i o n of the c u r re nt

s e a s o n 1s term ina l
mor nin g,
brought

growth.

They wer e col l e c t e d in the

pl a c e d out of the light in b r o w n paper bags and
into

the laboratory.

L e a f w e i g h t m e a s u r e m e n t s we re d e t e r m i n e d on a dry
w ei gh t

basis.

ation,

plus

The

50 leaves u s e d for c hl orophyll

an ad di tio nal 25 leaves were dried in pa p e r

bag s in a co nsta nt tempe ra tu re oven at 65° C*
were

co o l e d in a dessicator,

possible,

determin­

and weighed,

on a Tr ipp balance.

as r a p i d l y as

S p e e d was ne c e s s a r y in or der

to eli mina te w a t e r a b s o r p t i o n b y the leaves.
of the 200 disks,

The samples

taken for chlor op hyl l

The dry weight

samples was 0 o433 mg*

This c o r r e c t i o n wa s ad de d to the total w eigh t bef ore d e t e r ­
m i n i n g the avera ge leaf wei ght .

The values we re e x p r e s s e d

as mg. p e r leaf.
Chloro ph yl l was

dete rm in ed acc ord in g to the m e t h o d

d e s c r i b e d by C o m p t o n and B o yn ton
diameter,

(9).

Two

disks,

we r e t ak en from one side of 50 leaves

and t r a n s ­

ferr ed to an a mbe r glass bo ttle co n t a i n i n g 30 ml.
percent ethyl alcohol.

\ inch in

of 95

A duplicate sample was taken from

the ot her side of the same 50 leaves.

The follo wi ng m o r n i n g

the amount of c h lo ro phyll was d e t e r m i n e d in a K l e t t - S u m m e r s o n
p h o t o e l e c t r i c colorimeter,
a pp ro ximate

spectral range of 640 - 700 mi lli mi cr ons.

c o l o r in the original
alcohol

us ing a red f il te r h a v i n g an

In the

Any

alcohol was co mp en s a t e d by pl acing

s o l u ti on cell and ad ju st ing the c o l o r i m e t e r

to the

zero p o s i t i o n before each rea ding of the unknown.

The c o l o r i m e t e r wa 3

cal i b r a t e d w i t h a sta nd ar d solu tio n

c o n t a i n i n g a k n o w n amount of chlorophyll *
was o b t a i n e d b y d e t e r m i n i n g the
In a C o l e m a n U n i v e r s a l
method

(2).^

This

so lu ti on

total chlorophyll

Spe ctr ophoto met er,

content

us ing the A.O.A.C.

The values wer e e x p r e s s e d as mil l i g r a m s of

total chlorophyll

p e r 100 square ce nt ime ters of leaf area.

Total n i t r o g e n was d e t e r m i n e d on the dried leaves.
The

samples were g ro un d in a W i l e y cutting mill u si ng a

l|0-mesh sieve and s t o r e d in am ber glass bottles.

Ni t r o g e n

wa s d e t e r m i n e d b y the offici al K j e l d a h l - G u n n i n g m e t h o d
and the

values we r e e x p r e s s e d as pe rc entage

the dry leaf w e i g h t

of ni tr ogen In

and as m i l l i g r a m s of n i t ro ge n pe r leaf.

Y i e l d records w e r e
as total

(2)

taken each year,

and we r e e x p r e s s e d

oushels per tree, w h i c h include d the drops as well

as the p i c k e d fruit.

T h e d r o p p e d fruit wa s pi ck ed up and

m e a s u r e d af t e r the p i c k e d fruit ha d be en r e m o v e d from the
orchard.

1.
The sta nd ar d solution was analyze d in the Plant
N u t r i t i o n L a b o r a t o r y at the P e nns yl va ni a State College, by
J o s e p h Wet zler .

RE SULTS
C o v e r Crop W e i g h t s

The w e i g h t s

of the L a d i n o

and b l u e grass co ver crops

e x p r e s s e d as fresh we i g h t in tons per acre are

shown in

Table I I I .
There wa s

a def inite rela t i o n s h i p be tween the amo un t

of f e r t i l i z e r applie d and the w e i g h t of the co ve r crop
p r o d u c e d in b o t h covers and in all three years.
be n o t e d that there was

It will

a m u c h la r g e r dif fe re nc e b e t w e e n

the low and the m e d i u m fe r t i l i t y plot

values than be tw een

those for the m e d i u m and hi gh f e r t i l i t y plots,

Figure

3*

T hi s m a y be e x p l a i n e d by the fact that the low fertili ty
plots r e c e i v e d no o ho so ho rus and p o t a s s i u m in their f e r t i ­
l i z e r tr eat ments.

Since cover crops n e e d these n u t r ients

for the b es t u t i l i z a t i o n of availabl e nitrogen,

the covers

i n the low f e r t il ity plots wer e h i n d e r e d In their d e velo p­
ment.

The a d d i t i o n of ph os ph o r u s and p o t a s s i u m with ade qua te

amounts of n i t r o g e n in the m e d i u m f e r t il it y plots,
s t i m ul at ed the gr o w t h of both the Ladino
plots.

g r eatly

and the blu eg rass

Doubli ng the amount of fer til iz er a p p l i c a t i o n as

in the hi g h f e r t il it y plots had only a slight effect in
i n c r e a s i n g the p r o d u c t i o n of the cover crops.
pr o d u c e d

The L a d i n o

c o n s i d e r a b l y m o r e v e g e t a t i o n as m e a s u r e d by w ei gh t

TA BLE I I I
W E I G H T OP COVER OROD C L I P P I N G S AS RE LA T E D
A P P L I C A T I O N S EXPRESSED AS FRESH ^ E I G H T I N

Cover
crop

Ladino

Bluegrass

Fertili ty
le vel

FE R TILIZE R
TONS PER ACRE

1 947

191+3

1949

T 01 al

Average

IIigh

ie.79

23 .07

11.43

59.32

19.77

Medium

18.19

23.73

11.20

53.17

17.72

Low

18.97

10.39

3*29

25.75

80 92

High

14,78

12.32

9.42

36.02

12.00

Medium

11.52

11.92

3.33

31.77

10.79

5.03

9.37

2.99

17.39

5.79

Low

30

191+7 -----1 9 1 + 8 -----\

20*

15

'

\

Weight

of

cuttings

- Tons

per

acre

1 9 1 + 9 ......

10

Hi g h
Medium
Fertil it y
Ladino
Fi g u r e 3*

Low

Hi gh

Medium

Low

Fertil it y
Bluegrass

W e i g h t of two cuttings of cover crop? in each
y e a r in re la ti on to f e r t i l i t y levels and
y e a r s of sampling.

of cli pp in gs tha n the b l u e g r a s s u n d e r si mi la r conditions.
However,

this m a y have b e e n due to tne fact that the high

fe r t i l i t y h a d s t i m u l a t e d tho gr o w t h of grasse s more than
the m e d i u m level of fertility.
grasses,

in a large measure,

This add itional

growth of

ac c o u n t e d for the g r ea ter pro

d u c t i o n of c l i p p in gs from the L a d i n o plots r e c ei ving the
h i g h level of fertilizers.
Th ese dat a b r i n g out the

fact

that an

the f e r t i l i z e r a p p l i c a t i o n m a y be n oted in
response,

early effect of

the cove r crop

w h i c h wi l l e ve n t u a l l y improve the co n d i t i o n of

the soil.

I n turn,

this

should provide

c o n d it io ns

for the trees.

better gr o w i n g

Tree G r o w t h

Shoot Gro wth
Ta ble I V shows
1 9J|J| to 191+9,

shoot g ro wth li ne ar me as u r e m e n t s

e x p r e s s e d as average values p e r tree,

t a b u l a t e d a c c o rdi ng to fertilizer,
a pp l i c a t i o n s each year.
for the var io us

from
an d

m u l c h and co ver crop

It also gives the average values

treatments

and the least

signific ant

differences•
The

average shoot growth

before the

study started,

the

data for all

trees show that

trees were r a pidl y decli nin g

in vi g o r and that the ex pe rim enta l treatmen ts che ck ed the
decline,

f i n a l l y p r o d u c i n g an increase

The average

in the fourth year*

growth for all treatments in 1 9 4 4 was 7* 3 ? cm.

TABLE 17

H igh

Medium.

Low

T o ta l

A ll

198?

3.87
8. 70

7.86

3- UJ
3 .6 2
3 .87
6.03

3.22
9.00

3 .2 9
? d >6
3 .2 6
3 -8 8

7 .8 7

o .l3

3 .9 2

3-80

3 .2 8

6 .0 5

8. oo

Pea v in e
S tra w
L a d in o
B lu e g r a s s

5.3 2
e.31

6 .6 3
6.13

0.68
. 10
I

6.00
0. 1?

?. 77
3 .87
3 .28

Average

6,60

Pea v i n e
S tra w
Lad in o
B lu e g r a s s

^ gp

Ground c o v e r

17.V,

1986

Pec. v in e
S tra w
Ladin o
B lu e g ra s s

7.12
7. 21
,*.
.->2
7 .9 6

6.21
6,oo

A verage

)9 8 p

198?

Averag'

,6.20
6 .9 9
8.77
6 .7 8

3 <78
3 .7 2
3 .7 8
6.91

1
1

F e r tility
le v e l

u>
4--

ALT!UAL LI ILLAH SHOOT GAD ATE IT RKLAT ION TO BERTILITY LEVELS AIL)
GROUND COVERS, EXPRESSED AS CELTTVETTAG PEE TREE

6 .7 6

2.29

2 .2 3

2.88

o
o rr
^. o

2.26

8.18

3 .7 1
2.92
3 - 68

2.61

3 .27
2 .9 5
3 .7 0

?. 68
3 .1 7
2 .9 1
3 .51

6.18

3*82

3.12

2.81

3*20

3 .0 8

8 .7 6
3 .8 8

8.18

6.21

8.72

2.72
1,66

3 .3 2
2. 32
2 .3 6
1.63

3 ,^ 5

0.68

4 * 01
2/4
3 .0 9
2 .82

2 .7 6
2.09

7 . 6h

6.33
6. 0?
6.37

Average

7 .6 3

6.26

8-11

3 .2 3

2.30

? -83

Pea v i n e
S tra w
L a d in o
B lu e g r a s s

6. 8U

3.66

3 .78

3 .39

2 .3 6

0*o 0

6.72

2.86
2. .s7

3*39
3-6 9

3.28
* 2d

6.21

3 .6 1
7 .7 8
8 .3 2

3 .3 6
3 .6 6
3.08
3.62

2.80

7 . 90
7.73

6 .3 6
6 .7 6
6.72

A verage

7 .3 6

6.87

3.83

3 .8 0

2.67

3.60

8

. 0 7

8.08

■' f ; ;~jt LE. i t y

">

■Ban

-v '■ i i'

?

J

X1

3• 06
2 .3 1

3*02

j

3.57

3 .3 7

and by 191+8 h a d d e c l i n e d to 2 .67 cm*
du c t i o n in shoot

The gre at est r e ­

gr o w t h oc c u r r e d before

the experi men tal

treatme nt s h a d h a d time to influence the results,
v a lue s b e i n g 5*87 in 191+5 and 3*83 in 198-8*

the

Ana lysis

of v a r i a n c e on the data from 191+6 to 191+9 showed that there
was no
values,

s ig ni ficant d i f f er en ce betwe en
but

the 191+6 and 191+7

that the r e d u c t i o n in 191+8 and the increase In

191+9 w e r e b o t h s ig ni fica nt at the one perce nt level*
average figures,

however,

show only the general trends

m a s k the ef fects of the various

fertilizers,

The
and

mu lc h and

cover crop treatmen ts *
Shoot growth res pon se

after 191+6, v a r i e d In relation

to the amount of fert il iz er applied.

The average values

for the 191+6-191+9 p e r i o d were 1+.00, 3*01+ and 3*02 cm.
the high,
The

m e d i u m a n d low f e r t i l i t y levels,

for

respectively*

value for the h i g h f e r t il it y was s i g n if ic an tly great er

th an those on the m e d i u m and low ferti li ty levels even at
the one p e r c e n t level.
di ff ere nc e b e t w e e n the

There was,
figures

however,

no significant

for the m e d i u m and low levels

M u l c h and cover crop tre atments p r o d u c e d some slight
di ff e r e n c e s in shoot
than th os e

growth,

but they were less p r o n o u n c e d

caused by the f e r t i l i z e r applications.

avera ge values
cally the same,

for the four cover tre atments were p r a c t i ­
3.39,

3.28,

3.26 and 3.57 for the pea vine

and straw m u l c h and for the Ladi no
crops,

The

res pe ctiv el y.

and bl ue grass

These differ en ce s we re not

cover
significant

In order to minimise original differences in tree
size,

shoot growth was expressed In percentage of the 1988

values,

see Table V and Figure 8*

Although the percentages

showed the same trends as the figures for actual growth,
they made several facts more evident.

In the first place,

they showed clearly that the trees in the three fertility
plots were losing vigor at the same rate when the study
started*

The 191+6 shoot growth measurements were quite

similar,

representing 1+9*8, 5l ♦9 and 58-*7 percent of the

191+1+ values for the high, medium and low fertility,

respect­

ively (Figure l+A ) •
In the second place,

the percentage figures

clearly the effect of the three fer t il it y levels.

showed more
By 1987*

the h i g h fe rtility treatment had checked the per centage
red u c t i o n in shoot growth,
it to

some extent,

the do wnward trend.

but

the m e d i u m fertility ha d reduced

the low fe rt ility h a d not altered

A l t h o u g h shoot growth was

all trees in 1988 , the per centage

smaller on

values showed the definite

r e lat io ns hi p b e t w e e n the three fert ility levels.
in 1989 * shoot

Finally

growth in the high fertility plots represen ted

68.1 percent of the 1985- values, those on the med i um fertility
plots r e p r e s e n t e d 88*6 percent,

while those in the low

fer t i l i t y plots re p r e s e n t e d only 32.3 percent of the 1988
shcot growtl *
A l t h o u g h there were no significant differences between
the ce nt im eter s of actual

growth for the ground cover treatments

: / "];
A M : UAL

Ai.ii>
F e r tility

■:?{()w

L IN E A U
j

SI^CX>T

G / . C . / ; ';

cgveus,

Ground c o v e r

V

J:

d

••JT /.T IG G

19V

Medium

Low

T o ta l

A ll

. ’’ T ’T I M T V

■->- fo

l/A 'ii- L G

1933 v a lu e s

19U6

1/37

1736

3 7• 9
tP
d♦
5i . o

3C..
31.5
57. 3
y1-' * P
-

9 '. ]
7- • •
53. 1
36.5

l e v e l

H ig h

TO

as PAHCidrrAGd U-* t h e

1939

A--

1‘

•

Pea v in e
S tr n v,
L a d in o
B lu e g ra s s

... . .
76. 'A
7 f .?

Average

77.9

3?. 6

3 7 .;

3 1.2

6)1. 1

30 *°

Pea v in e
S tra y .
1
L a d in o
B lu e [^rasa:

03-7
6 1,3
7 o ♦'i‘
7 rJ a
1. • -

37.1
3 3.o
3?. 3
3 1 .3

9 3 .0
5 6.7
3 3 .3
3 3 .5

3 1 .9
3 5 .7
3 6.7
3 2.?

5 3 -J
5-i • ’
3 3.6
5 5 .7

1. 71 * rU
36. "<
33. 3

Average

76-5

51-9

3 7 .?

35.5

3P6

36. !

Pea v i n e
Straw
la d in o
B lu e g ra s s

6<u3
71 -?
Od»5
9 5 .5

6 0.3
1—
U
53 .J
g/ /

5 3 .1
30.?
).'■
^ 0
,
or ®c7

3 5 .0
25.3
3 5 .0
2o «7

)|2.1
2 6.7
31-3
25.6

3t . ■
36. 1

A verage

1 3 .0

^'-4 *

' •' * O
U
s

3 0 .6

32-3

3‘ .

Pea v in e
Straw

7o *
73 .6
"’1 O
V
. . V

B lu e g ra a s

61 -

53.6
5c. 0
1.
55 • w
3 5.?

U,:*
\ r

L a d in o

3 3 .2
32.3
37- 5
3/a- . 1

30.9

So. l

A verage

7 ? .^

n
ij
C

?.

?

i

,

53-5

52 * a

r'

I'

7

j

32.0
39.5
3 2 .5
/

9

J

S

• 'B
56 . 2
64- /

UA «

1

00

-

97. '

3 ->a -■

1

3 l: . 3
s i

^

•V. - '

CL
c.
o

o

-p

o
r-1
o
r»

1
—i

o

*3
0
>
0

fH
f0>
P

•rtf
<— I

<D
3
i
—I
ctf

<»O'

•H

P

U
0

Ch

>

4)
aC
ctf
C.

JO
~ri

o

CJ

>

o

<

C
<P
c-

O'

o

ctf

0)
H

C 0)
O >
<P 0
f—I
u
ctf
VO

0
O

P
O

o

t

J>H rtf P
Ctf *rtf

> r— !
♦H

0 P

OC Cl
C. C..I

ctf O
0

>

<

o

o
CO

o
cO

O

ggrjBA ^?6l J° o^'i} uoocroc ~

o
CO

O

\A
q.ooiJS

Otf

b y 19l|9> the perce nt ag e
.growth in the
shows that

increase indicated somewhat

elcts liavin^ the r>ea vine mulch,.

suoericr

Figure q_B

the shoot gro wth for all trees receiving oea vine

mu lch r e p r e s e n t e d a sligh tl y h i gher percentage of the 191^4.
values,

each year,

covers*

than did the average

F i gu re L^C shows that

values for the other

this superior shoot growth of

trees in the pea vine clots was partic u l a r l y evident in the
low f e r t i l i t y level,
of the 19iili figures.

the values

representing 1|2.1 percent

O n this same level,

the trees in the

L a d i n o plo ts r e p r e s e n t e d 31*3 percent while those for straw
and b lu eg ra ss r e p r e se nt ed only 28*7 and 2l|.8 percent,
respectivel y.

Thus the effect of the ma ter ials

supplying

n i t r o g e n was mo re evident on the low than on the other
fertility levels.
T ru nk Cross Se c t i o n Area
The

annual

average trun k cross sectio n area per tree

for each treatment is shown in Table VT .
sho wi ng the actual values,
in tree size
the trees

Those data, while

do not consider the differences

at the be ginnin g of the experiment.

For example,

in the hi gh fertilit y plots had an average area

of 755*'i sq . cm*

at the beginnin g of the study, while those

in the m e d i u m and low fe rti li ty plots ha d average areas of
917.1

and 891.7

sq . cm.,

respectively.

Alt ho ug h the trees

in the h i g h fertilit y plots made good growth,

they were still

smaller than the others at the end of the study.

Thus,

it

T-OiLE VI

ANHUAL TV 11Hli GKOSS SHOT 10 [,1 A Si cl Pi A. TALK,
0TBG TO
THE V'vlUO US F 1
W TL1TY L -VAIS al. .1 In0671 GOV. -7,’f'
F e r tility
le v e l

Ground c o v e r

191(5

1986

190

3968

1969

(sc;. caw)
H igh

Medium

Low

Pea. v in e
o i l ' aw
L a d in o
31 u e g r a. s s
A verage

76'-

726.8
i* ,
769«3
611. a

766.7
76 1.8
777 - 0
863.1

78': . 8
i J *■ u
8Or , V
80:. . 3

817.2
809.8
866.6

83 A «
826,?
861. 1

9 1 7 .3

936.8

.6

776 . 1

coo. #

866.2

0o 2. e

Fee v in e
S traw
L a d in o
B lu e g ra s s

9 6 6,0
9 6 1 .A
8e:,.e
8? : . i

962.8

998

986.3
903.6

102'J

1066.8
108: . o

896.0

966 .
936 - '
0

1126.9
I j o 7.?
9o6.7

Average

917.3

930.?

970

1007.6

1026.3

Pea v in e
Straw
L a d in o
B lu e g ra s s

909-2
8 63.6

9 30.2
8 7 0 .6
9 6 3.8
800.1

969 g
906 . 3
983 .
i
906

999 .3
932.9
103 9 -8
930.6

ICG L ,0
969.?
1036.1
963.6

A ve r cage

891 ♦ 7

0 7.'; p
>■ •- ^ • *-

961 . 6

972,

(

<-

92^.8
M i .

8

•^
n
’

^

n ,•

-1

92a .a
992.6

9c , »6

was n e c e s s a r y to exp re ss
mental

the effect of she various ex p e r i ­

t r e a t m e n t s by some other measure.

several me th od s

of ex pr essin g trunk size increase,

found that the per ce nt age
reduced the eff ect

increase in trunk area each year

relationsh ips to the treatments.

gives the average percentage Increase per

tree in the trunk cross
mulch,

it was

of the original trunk area and showed

the m o s t c ons is te nt
Table VII

A/"ter testing

section area tabu la ted according to

c o v e r crop and fer til izer a p p l i c a t i o n s .

gives the le ast

It also

significant differences between the values.

A l t h o u g h there were considerable differences in annual
gro wt h d ur in g the four years,
amount of f er ti li zer used.
the trees

the growth was related to the

Even In the first growing season,

in the low fertility plots

showed inferior growth

and those in the h i g h fer tility p l o t 3 grew at the most rapid
rate.

The average percent ag e increases over the four year

pe r i o d we r e

3»5>5 for the high,

for the lo w fe rtil ity plots.

2,98 for

the m e d i u m and 2,68

Statistical eva luation showed

that there was a significant difference at the one percent
level b e t w e e n the per cen ta ge
m e d i u m fe rt ility levels,

Increases for the high and

but only at the five percent level

b e t w e e n the m e d i u m and low fertility

treatments.

The average per centage Increase in trunk area for all
trees

sho wed that there was an annual var i at io n in growth.

Du rin g the first
fruit production,

three years, w h e n there was ve ry little
the per centage

increase was larger each

31
TA B L E V I I

TRUNK CROSS SECTION a r e a EXPRESSED AS AVERAGE PEY
INCREASE PER TREE, ACCORDING TC THE VARIOUS
FERTILITY LEVELS AND GROUND CC-/ER3
Fe r t i l i t y
level
Hi g h

Medium

Ground

cover

Total

All

1947

■> ' I.Cl
± 74‘-j

Pea vine
3 braw
L adino
Bl ue gr as s

2.60
2 c26

9 . 97
k . c4

i. •^4
°- •C
'Ji
<
74

3. ‘39
5 -49

U .37
0 .52
r'.01
3.55

Average

2.63

u n

Pea

1.77
I ,90

3.32

vine

S traw
L adino

Loitf

1396

2,10

A.io

191+5
- //
«O O
;r*
•-•J?
2 .13

Average

2.67

3.77
3* 92
3.90
3 .61+

3.71+

2 .99

3 066

3.31
I
1-1*9°
4/
3*72
9. 63

2 .03

1 . ^6
2.03
2.30

2 ,91
3.7)0

2,47
2*39

Bluegras 3

o .67

3.35
3 •95

Average

2,03

3-75

9.02

2.06

2 . -3

Pea vine
Straw
Ladino
Bluegras s

2*31
1.79
1.96
1.31

3.83
3.'+5
3 .03
0 m>"<oJ
1

3.71
3.09
9*09
2 .99

1.73
1.39
1 .63
1.46

2,71
->* e-4
,
£
2.93
0 97

Average

1.96

3.61

3.60

1*66

0 AC

Pea vine
Straw
Ladino
Bluegrass

2.23
1.97
<_•13
2 *9*9

9 o06

3.96

4 •D3
3.67
3.72

9 *09
9 .23

3.01

2,14
2,03
1 .Q3
2.11

d.io
3.03
3-d?
3.03

A verage

2.21

3.93

9 .09

2 o09

3. 07

L.S.d .

it

Per tili ty
0 .306
0 .9-03

Ye ar s

Cove rs

0.363
•9o0

0,363
0 .400

year,

bu t i n the four th year

the pe rcentage

growth decreased.

The d i f f e r e n c e b e t w e e n the values for the first and second
years was

s i g n i f i c a n t l y hi ghe r at the one percent level and

the decrease b e t w e e n the third and fourth years was si gni fi­
ca n t l y lo w e r at the same levelFigu re

5>A show

The cumulative data in

how the diffe rences

between the three fertility

le vels i n c r eas ed as the fert il izer effect built up,
range b e t w e e n the high,

the

m e d i u m and low becomi ng greater

each year.
The m u l c h and cover crop treatments ha d little effect
on the p er centag e of trunk area increase except in the low
f e r t il it y plots,

Figure

growth measurements,
Lsdino

These values were high er than tho

2. 6 9 p e r c e n t for the straw

the

as also noted for shoot

pr od uce d percentage increases of 2.93

resp ectively.

bluegrass.

Here,

the two covers suoplying nitrogen,

and p e a vines,

and 2.91,

5>B •

and the 2.27 percent

for the

Thus the data indicate that the two legume and

two no n - l e g u m e materi als were ass ociated rather than

the two m u l c h and the two cover crops.

The average values

for each of the g round co ver treatments mask the variations
and thus

they w e r e not

significan tly different*

Le a f Growth and Composition

L o a f Heigh t,

Chlorophyll

and N i t r o g e n Data in 1997

The data for leaf weight,
p r e s e n t e d in Ta ble VTII

chlorophyll and nitrogen are

and Figure 6.

The table gives the

12'

11

io

section

area

- percent

increase

13'

Trunk

cross

Pea vines
S traw
Ladino
Bluegras s

191+5

191+6

I9k7

191+8

191+9

Increase for each fertility
level oer year

Figure

High

Medium

Low

Average increase for
mulches and cover crops
according to fertility
levels

Percentage increase in trunk cross section area
in relation to fertility levels and ground covers.

T A / 'L E V I I I
L E A F ’•’EIGHT,

CJ!LCROnHYL L AMi) MITROGETJ VALLES FOR lvl+7
A C O O R o I F O TO FLRTILTTV LEVELS ATI0 GRe UTIL COVERS

Fertility
1-3 vel

High

Medium

Low

Ground cover

B e irh t
per leaf
('ng. )

Cdloro od/ll
(rng/100 sq . cr .)

Tc tol
ritrog.
(perc^i

Pea vino
3 traw
Ladiiic
Bluegras s

125.0
153.7
lpl.d
127,2

1 ,36
1.63
1.32
1.10

1.5k;
j-.■>a
1 •ol
1 .52

Average

139.3

1 •j»0

1 «’y'j

Pea vine
Straw
Ladino
Bluegras s

125.9
135.3
129.9
li+P.O

1.13
1.12
0 .96
:. 99

1 *43
i .64
1 .n9
^t
• F1

Average

133-4

1 .06

1 F :4

Pea vino
31raw
Ladino

113.9
113.3
139 . 5

1.07
9.95

I •+7
1.33
1 •q-1

Bluegras s
A yerage

0r

n

115 ,9

0.37
c. ro
0
0
^ 0 <-

1.29

1 . -F-

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Figure

©or junk1

-p

CO
CO
c
t
f
I
m
to
©

in 19lj.7
respect

co

Leaf analyses
nitrogen with

o

>>

p
•iH
r—J

and

m
S
f»H
TO
©
IS

as measured by dry weight, chlorophyll
to fertility levels and ground covers.

o
X

V ■

figures

tabulated

ac cord ing to mulch,

ti li ze r tre atme nt s and the figure

cover crop and fe r­

shows

the average values

for each g r o u n d cover treatment on the three fer tility
levels•
E v e n as ea rl y as 19i|7, the various treatments influen ce d
the values for leaf weight*
fe r t i l i t y level
li zer applied,

figure for each

varied directl y with the amount of ferti­
the values

p e r le a f for the high,
respe cti vely.

The average

These

being 139*3#

133 «0f and Ilf..9 mg.

m e d i u m and low fertility plots,

figures indicate that there was little

d if fer en ce b e tw ee n the trees in the m e d i u m and high fertility
plots,

but that the trees in the low fer ti lit y plots were

in mu c h p o o r e r condition.

There was a considerable v a r i ­

ation in le af w e i g h t b e tw ee n tho various mu lch and cover
crops w h i c h was not al to gethe r consistent w i t h the different
fe r ti li ty levels.

Straw and Ladi no in the high,

in the m e d i u m and Lad in o
to produ ce

bluegrass

in the low fe rtility plots

seemed

somewhat larger leaves than did the other treat­

ments •
Ave ra ge

chlorophyll values also varie d in relation to

fe r t i l i z e r applications,

being 1 .30 , 1.06 and 0.92 mg.

per

100 sq. cm, from the high, m e d i u m and low fertility plots,
respectivel y*
me n t s

showed

The data for the mulch and cover crop trea t­
some slight differences,

each t r e a tm en t were proporti ona l
cations.

but the values for

to the fe rt ili zer appli­

The leaves fr om the pea vine and straw plots had

sli ghtl y h i g h e r c hl orophyll
bl u e g r a s s

figures than those from the

and La d i n o plots.

At ea c h f e r t i l i t y level,
were a g a i n p r op or ti on al
The figures,

the average values

to the amount of fer til izer applied.

e x p r e s s e d in percentage

for the high,

for nitrogen

of dry weight,

were 1.58

1 « pJq for the m e di um and 1 J4I for the low.

The

as shown in Figure 6 , was almost

drop in the low level,

e n t i r e l y due to the low straw and bluegrass values.

The

perce nt n i t r o g e n in leaves from the Lad in o and pea vine
plots r e m a i n e d p r a c t i c a l l y the

same on the medium and low

fe r ti li ty levels, w h i c h in dicate d that these two materials
mu s t have

supplied some

These three
the differ ent
take effect,

additional nitrogen to the soil.

determination s on leaves all ind icated that

amounts of fer tilize r applied had started to
althoug h the variations were

small.

At this

time, the m u l c h and co ver crop3 h a d had little influence
up o n the results.
Since the values
n i t r og en

for leaf weight,

all f lu ct ua ted in r e l at io n to

chlorophyll and
fertilizer appli ­

cations and since chloroph yll contains nit rog en in its
molecule,

corre la t i o n s we r e made bet ween these three

of data.

There was no relati onship

chlor oph yll

sets

between the figures

and eith er leaf wei ght or total nitrogen,

for

the

c o eff ic ie nt of cor relation s be in g + 0.17 and + 0.3d-# r e s p e c t ­
ively.

There was,

however,

some relationsh ip between the

w e i g h t of the leaves and the total ni tro gen content,

since

the c o r r e l a t i o n was
that th e
g r eat er

total

f 0,71,

From this it could oe assumed

amount of nitroge n in the larger leaves was

than the p er c e n t a g e figures indicated.

Leaf height,

Chloro ph yll

Two years later,

and Nitrogen data in I.9I4.9

in 19ll9, the study of leaf weight,

c h lor op hy ll and n i t r o g e n content of the leaves was made on
a more

ex tensive

scale.

Samples were

d ur in g the g r o w i n g season,

taken four times

on June 7, August 1,

September 15

and O c t o b e r 15*

T h e s e data not only show the effect of the

various mulches,

cover crops and fertil izer applications,

but also

show the leaf weight,

fluctu a t i o n s

during the growing

trees h a d r e c eived. th e

chlorophyll and nitrogen
season.

At this time the

treatments for four years,

so the

original val uat ions in tree size were less obvious

and the

relati on sh ip s b e t w e e n these me as ure ment s were mors accurately
p o r t r a y e d than in 191+7 •
permit

There was also sufficient data to

analyses of variance,

wh ich furth er substantiated the

results obtained.

Leaf weight.

The dry weight of the leaves,

as milligrams per leaf,

are recorded in Table XX,

calculated
The data

are tabulated according to the cover crop, mulch and ferti­
lizer applications.
Leaf weight and thus the original size of the leaf
showed a definite relation to fertilizer application..
sidering all data together,

Con­

the values were 21+1*7, 221.6

>/

TAILS IX

Lot:

:i I IT 3 IF
9'iOTiML

F e r tility

___

1 ''V •:1

High

Medium

Low

T o ta l

A ll

.FLT
ABO
^ ^ da.-

I ::v- 7
(• •'. )

Aug. I
(•• . ;

Pea -fin e
l i t raw
L a d in o
illu e g ra s s

22 / . :
2 2? . ?

2 2 7 .7
2 1 3 .3

O ' I1. * 'ii
t_
^OJ' i * ^0
27; .0
p n ' ->

2 3 7 ,o
239.
263, 3
261.2

21, .0
22 .

O
«-'4i”• *•
2 -3 .
<L *
261 .

A v e ra g e

22,3.9

2 3 9 .0

262 . ?

2 9 9 ,6

231 *

Pea v in e
S tra w
L adin o
B lu e g r a s s

2u p .3
21,1,6

256.7

1 9 3.3
1 9 3 .7

236 • 6
212.2
261.?

259.3
23333
213*7
233 * 7

227 . 9
217.0
.1P7I . 2
191.5

2,36. ?
230, 7
200, I
217. 5

A ^ e ra ge

202T?

232.2

237 <

203.3

221-n

Pea vine
S tra w
L a d in o
B lu e g r a s s

221 ,3
1 75.5
1 9 6 .0
153*7

261.5

199*5

13 .5
203 . 6

4.63 . )

A verage

185.3

Pea v in o
S tra w
L a din o
B lu e g ra s s

A verage

(a-.)
(r-

/"‘
. 'if -■>
C-j ± . ‘

183.2

1 67.3
1 70.5

23,o
l- o .'j
20 I . 3
160.9

220.0

207.3

136.3

200.3

219-9
2u* *, ■+
203* I
169. i

257.3
2 3 6.3
2 33.3
23 7.2

26g . I
227.3
226,3
22-L3

219.3
203*9
193.9
199,9

239.9
213 >y
2 .2
213- 1

2 03.3

231*1

236.2

203*5

221.3

253

-7

1 9 3 .2

223*0
216.2

F e r tility

l.s.d, 3;
1%

Say: , 2
('■'.)

P-7o
11.79

L a te

Govre r

13.11
13*39

10 ,.11
13*39

)

i

j

and 200*3- we*

oez"* leaf for the high,

tility levels,
variance
different

res pectively,

sho w ed that

me d i u m and low fer­

A statistical

these averages were

analysis of

significantly

even at the one percent level*

The general

averages,

however,

did not show the

differe nce s in the d e v e l op me nt of the leaves during the
g r owi ng season.
period

The average

values for each collection

.bowed that the leaves ma inta i n e d their ma xim um

weight l o n g e r in the hi g h e r f er tility level*

O n July 7,

w h e n the first

of the leaves

samples were

taken,

the weight

was d e f i n i t e l y r e l a t e d to the fertil izer application,
from the hi gh f e r ti li ty plots being the heavier,
On all three f e r t i l i t y levels,

differe nc e

same rate,

in total weight.

the t h ir d sampling in September,

keeping a

At the time of

the leaves in the high

f e r t i l i t y plots ha d in cr ease d and
low plots ha d d e c r e a s e d in weight,
lowest in the low fert ility

Figure 7 A *

the leaves p;rew until the

first of August at a p p r oxim at el y the
pr op or tional

those

plots,

those in the me d i u m and
the reduc tion oeing
3y iotober ly,

all

leaves ha d lost w e i g h t and ha d r e ac he d the approximate
weight of the Immature leaves co llected in June,
differences

in leaf weight

of fertility,

These

Indicate that with hig her levels

the leaf ma intains its ability to produce

plant n u t r i e n t s longer and thus

best iulfills its function

in the gro wth of the tree*

average increase in weight

from Ju ne

to August

The

and the decrea.se from September to

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O c t o b e r were

si gni ficant

levels of fertility.

at the one percent level,

at all

There was no significant difference

b e t w e e n the August and September values in the high and
m e d i u m f e r t i l i t y levels,

tho difference between these

but

c o l l e c t i o n date3 in the low fertility level was significant
at the five percent level.
During the entire g r owin g season,

average values

that the pea vine m ulch pr od uc ed he av ie r leaves
of the oth er covers,

Figure 7 F.

others decreased*

This

at the third sampling

the values for all cf the

su per iority of

the pea vines was

s u b s t a n t i a t e d by the analysis of variance,

'which showed

that there was no difference between the values
straw or bluegrass,

but that

than did any

I n addition the leaves from

the pea vine plots increa se d in weight
p er io d on Se ptemb er 15, while

showed

for Ladino,

the figures for pea vine were

si g n i f i c a n t l y h i g h e r at the one percent level,

than those

for any of the other c o v e r s ,
The effect of pea vine m ul ch on leaf weight became
more p r o n o u n c e d as the fer tility level
In the hi gh f e r t i l i t y plots

Figure ?C#

the pea vine had little effect

on the size of the leaves which wore
in the last two

decreased,

sampling periods,

p r o n o u n c e d in the m e d i u m fertility
f e r t i l i t y plots,

the values

g r o w i n g season.

It is pr ob ab le

slightly hig he r only

The effect was more
plots,

were highest

but,

In the low

during the entire

that the pea vines

additional n i t r o g e n wh i c h pr od uce d the most

supplied

striking effect

w h e n the f e r t i l i t y was low,

chlorop hyll.
as mg, per 100 sg,
for leaf weight.

Averag e
cm,,

chlorophyll values,

shewed. V3.ri aticns similar to those

Tablo X gives the

l a t e d a c c o r d i n g to fertilizer,
me n t s

e x p p 6;s3sA.

and date of collection,

chlorophyll

values tabu­

mu lch ana cover crow t re at ­
tog et he r with the least

significant differen ces *
The c h l o r o p h y l l data varied ac co rdin g to fe rtilizer
applications,
high,

1.22 mg,

the average values being 1,36 mg.
for the m e d i u m and 0.97 mg.
statistical analysis

for the

for the low

f er tility levels.

The

showed that

these figures were

si gn if icantly different at the one percent

level .
O n ea ch c o l l e c t i o n date,

as shewn in Figure 8 a , the

average values for each fert il ity level were high at the
b e g i n n i n g of the
lea ves were

season and decreased gradually until the

almost

ready to fall from the trees.

on the high fertility level wer e
and Se p t e m b e r but

The values

almost the same in August

fell ra p i d l y In October.

Those on the

m e d i u m fe rt il it y plots h a d a more gradual decline,
all times were l o w e r than those on the high

but at

fertility plots*

The average chlorop hyl l content of the leaves

in the low

f e r t il it y plots was lo we r at their highest level

in the early

su mme r than were the values for the hig h fertility plots
at their l o we st level at the end of the growing season.
The decline was e x c e e d i n g l y fast

so that by the end of the

TABLE X
-JBIOitOPHYLL VALUES 'D’ r i i : r i : :Ig 195? SS-.SOt AS u EIATED TO

f ERT I LIT I LEVELS All.) GRGU’A IGVkAS

F e r tility
le v e l

Ground c o v e r

___
.
June 7

An-

i

D a te ____
S e p t.

(nr./lOO

1 *35
1. 56
l . 31

l . /o
i 3o
i .35
a1* d '?
i

-j1• o
<*
3 * 38
1,39
1.37

1.10
1. :,3
1.16
1.20

Average

2 .58

i .-4o

1,39

1* 1/

1.36

Pea v i n e
Straw
L a d in o
B lu e g ra s s

1 .3 0
i -37

1*28

1./2?
1• 35
1.22

1.26
.1. ?0
1.IB

1*3/

1 .2 9

1-33

~
•ii , n a
J . Do
v>< .-3
1. ! 53

1.23
1- 2d
1. i 6
.1. ?5

A ve r a re

1 .3 /

1 .2 9

1.23

1.03

Pea v i n e
S tra w
Lad i n o
Bu le g ra s s

1- 75
1.12
1. 10

1. ’
,9
1.10
1.02

1.12

i . o5

0.97

0 .93
0.87
0.33

0. 8?
0 .77
0»o5
0.73

2.77
0.91
0 .9 0

Average

1 .1 3

1 .0 7

0.93

0.76

0 .9 7

Pea v i n e
S tra w
Lad 1 no
S lu e g ra s e

1.50
1.38
1.29
1,3 0

1 - 29
1* 28
1.23

I

.93

1, 'i x

1. L5

0 .99

1.21

1.21

0,99

1.23
l . 18
i.i5
1.13

A verage

1. 32

1,25

•19

u. 18

1.13

-y*

Medium

Low-

T o ta l

A ll

J~i. r(V
JP
L «O *t
r*

V/o

1.. 59

l

1
j

'.22

:.1 3

Fertility

Date

Co ve r

0 .0 3 5

O.OLl
c * o 55

0 .0/1
o.o55

0.056

J . 3/

1. 32

:'7

i , 39

1
j
1 ,n
nj

Pea vin e
C +■ o
-'
'I
jc*r
.1r
Lad i no
131 i e g r ass

1
_1

H igh

1.11

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summer there

was o nl y 0*76 mg.

of chlorophyll

per ICO sq*

cn. of l e a f surface In the low fertility plots as compared
to 1.15 mg.

for the high.

Because the leaves In the low

fe r t i l i t y pl ots w e i g h e d less than those in the other plots,
the actual

amount of chlorophyll

Therefore,

the leaves

was undoubtedly lowest.

coulc. not produce as much food material

for growth of the tr e e or for the pro duction of fruit in
the low f e r t i l i t y plots as did those in the high and medium
fe r t i l i t y plots,

Cn the same basis,

had less chloroph yll

the trees in the medium

than those in the hi gh fertility plots.

C h l o r ophy ll values arra ng ed according to mulches and
cover crops,

Figure 0B,

showed that leaves on trees receiving

pea vine m u l c h h a d the highest
the ent ir e

gro wi ng

season.

in the L a d l n o plots,
in August,
the season.

amount of chlorophyll during

On the other hand,

trees growing

except for the one collection period

h a d the lowest leaf chlorophyll values throughout
Chlor oph yll

values

for straw and bluegrass were

be tw ee n these two extremes-*
The

relation shi p bet w e e n fe rti lit y levels and mulch and

cover crop treatm ents as mea s u r e d by leaf chlorophyll
i l lus tr at ed in Fig ure 8 C .

is

In the hig h fertility plots,

the

b l u e gr as s plots p r o d u c e d significantly higher chlorophyll
va lues

than the straw plots,

but there was no significant

di fferenc e in the other mulch and cover treatments.
m e d i u m f e r t i l i t y level,
lev els

At the

the Lad ino plots had somewhat lower

than those for the other three cover treatments,

which were practically the same.

At the low fertility

1evel, the chlorophyll values with pea vines were much
higher than the other cover treatments.

This effect of

pea vines on chlorophyll values at the lower fertility
level accentuated the value of this legume mulch which in
itself supplied considerable nitrogen to the tree.
Nitrogen.

Table XI presents the total nitrogen content

of the leaves, In percentage of dry weight, at the four
sampling periods in 19if9.

The data are tabulated according

to mulch, cover crop and fertilizer applications*
The nitrogen content of the leaves was again closely
associated with fertilizer applications.

The average

figures were 1*95 for the high, 1*58 for the medium and
1.63 for the low fertility levels.

The difference between

these values was significant at the one percent level.
The percentage of nitrogen in the leaves w a s highest
in June and fell continuously until October.

The differences

between the average values in June and August and between
those in September and October were significant at the one
percent level but the difference between the August and
September values was barely significant at the five percent
levelo

Throughout the growing season, the average values

for the high and medium fertility plots followed the same
general trend, Figure 9A •
summer,

They were high in the early

dropped rapidly to the August and September levels,

which were practically the same, and again went down in the

TABLE XI

PERCENTAGE 01v TOTAL NITROGEN IN THE DRIED LEAVES DURING 1.96? WITH
RESPECT TO F E t f f lL r r y LEVELS AMJ GROUND COVERS
"*
F e r tilit y
le v e l

June 7

m

—- -

l.
._l.

O c t. Ig

Average

2 .2 6
2.07
2 .2 2
2 .2 2

1 .9 5
1.67
1 ..22
.1.89

1.9 0
1.8 8
1 .8 9
.1.91

1 .7 9
l.tO
1. 82
1 ,8 0

J ,77
1.91
1..96
3-95

A verage

2 .1 9

.1.91

1.89

1 .8 2

1.95

Pea v in e
S tra w
L a d in o
B lu e g ra s s

2 .1 2
2 .1 0
2 .0 0
2.

1 .8 6
1.8 9
1 .7 9
1 .9 0

1 .8 6
1 .8 8
1 .7 8
1.8?

1 .7 2
1 .7 6
1.70
1.78

2.88
1.91
1.82
] . 90

A vera ge

2 .0 7

.1.85

1 .8 6

1 .7 6

1J38

Pea v in e
S tra w
L a d in o
S lu e g ra s s

1.92
1.79
1.83
1.68

1.62
1.59
.1.66
I . j2

1.5 6
1.69
1.51
I «4 0

1.70

1.67
1 .61
7- 67

1,60
1. 56

A v e r a ge

1.51

1 .6 6

1 .5 5

1 .51

1 * 63

T o ta l

Pea v in e
S tra w
Lad: no
B lu e g ra s s

2 .1 0
1.99
2.02
1 .9 8

1.83
1.6-1
1.77
1 , 79

1.79
1.78
1.71
1.77

1.69
1.69'
1.68
1.68

1-85
2. 82
1 . 79
1.80

A ll

Average

2,02

1.80

1,76

1.08

1 .8 2

Medium

Low

O k

1—

Pea v in e
S tra w
L a d in o
B lu e g ra s s

-0
0

H igh

Ground c o v e r

Date
An g . 1
S e p t. 15

F e r tilit y

L *o •0 .

/o
1%

0.036
0.0 6 7

Date
0 . 06-1
0. 05)4

1.66

Cover
U.Ga'l
0.056

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Figure 9«

P

Total percentage nitrogen in dried leaves during the 19^Q sspscn
influenced by fertility levels and ground covers.

o

October* analyses.
we re

The values

for the low fertility

clots

co nsiderab ly lower than those for the other clots and

they dr o p p e d co nt i n u o u s l y at each sampling period.
The ave rag e values for each of the covers are shown in
Figure 9B«

The p er ce ntag e of nitrogen in the leaves from

the pea vine plots was h ighe r than that for the Ladino at
the one perce nt level,

hi g h e r than that

at the five perc ent level,

for the bluegrass

but not significantly hig he r than

that for the straw,,

The hi gh values from the pea vine plots,

Figure

pro nou nced in the low than in the

9C,

were mo re

other f e r t i l i t y levels,
highest

the perce nt age s in that level being

at all times during the growing season.

I n or der to obtain a better unde rs ta nd ing of the tree
performance,

the n i t r o g e n data was also ex pre ss ed as m i l l i ­

grams p e r leaf,
a mor e

Table XII *

On this basis,

the values gave

accurate estimate of the total quanti ty of nitrogen

available to the trees on the variou s dates and at the
differen t fer ti lity levels.
The results were
n i t r o g e n In the leaf,

similar to those for percentage of
but the differences were accentuated*

The fall f r o m the high to the m e d i u m to the low fertility
was almost a straight line,
3.35 mg,

the values being ^*70,

of n i t r o g e n per leaf.

li,12 and

The average values for each

c ol le ction date m a i n t a i n e d the same relationships between
the three f e r t i l i t y levels as did the percentage figures,
but p r o d u c e d quite a different type of curve,

Figure 10A.

TARLii XI [

-

MILLI SRAMS OF NIT.100EN PER LEA, ' DURIM 1 THE 1939 SEASON IF RELATION
TO FERTILITY LTV1FIS AID CKO UNI) COVERS
- , ,— m — , ,t _ r ■
.
_,r___ _ _ _ _____

Fertility
level

_

Around cover

--- -----Aug. 1
June 7

Late
Sept. 15

Oct. 15

Averagt

Pea vine
Straw
Ladino
Bluegr'jss

3-i6
1,.a ;J
5-0?
a. Be

3.07
i . 7a
7.10
3 .p2

5*07
3.75
3.o3
3.98

3.13
3.76
-j p r>
-v►-5j
3-U

3.06
3.38
3.76
3.69

Average

3.93

A. 93

3 •96

3.97

3.70

Pea vine
Straw
Ladino
Bluegras 5

3.33
7.37
7*89
'3* '7

3.72
7-37
3.61
3. 35

3.77
3.32
3.62
3. 73

3.90
3 .76
-j^no
2.92

3.36
3.38
3. o5
3.99

Average

3.19

3.39

3.38

3-32

3 .12

Pea vine
Straw
Ladino
Blaegrass

3*26
3*15
3-37
2.33

3.33
3-27
3.57
3.38

3.26
2 •80
3 .01
2.01

3.11
2.02
2 .oh
2.38

3.99
9.03
o .22
2, 77

Average

3*33

3-63

3.23

2.82

3.25

Total

Pea vine
Straw
Ladino
Bluegrass

3«o2
3.09
a - lh
3*75

7.71
3.19
3.16
3.?5

3.70
3.0 1
3.96
3.11

3.72
i ■i
1*.1
v
3.2?
3.17

3.03
9 -96
3 .68
9-92

All

Average

A * Li

3.35

3.19

3.30

3.03

Hi gh

Medium

Low

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Total nitrogen per leaf during the 191+9
fertility levels and ground covers.

X?
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Blue grass

Ladino

Straw

?>
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High

Pea

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4->
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-p

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The val ues

In the h i g h

fertility level were

practically

the sane th r o u g h the S e p t em be r 19 analyses but
rapidly in October.
plots,

the

declined,

I n both

the me d i u m

then drooped

and low fertility

values rose rapid ly from June to August and then
those for the me d i u m ferti lity slightly,

for the low quite rapidly.
n i t r o g e n pe r leaf

but those

This ma int enan ce of the

total

during the summer as comp are d to the c o n ­

tinuous decline of the percentage nit ro ge n was exp lained by
the fact

that

the leaf wei ght in creased from June to August,

stayed at about

the same

figure until September and then

de c li ne d rapidly*
Since the leaves in the pea vine plots were much heavier
than those

from the ot her ground cover treatments,

iority of the pe a vine mu lch was accentuated*

All

the super­
values

w i t h this .ground cover were highest both in relation to date
of c o l l e c t i o n and to fertility level,

Figures 10B and 100.

The average value

for the pea vine plots was Ig.Mt

c o mpa re d to 3*96,

3,88 and 3.32 mg.

and b l u e g r a s s

plots,

respectively.

pe r leaf In the La d i n o

Ladino

The greatest difference

o c c ur red in the low fertility plots,
the d iffere nc e was less striking,

for the straw,

as

Figure 10C.

Although

the weight of nitrogen

plots in the low fertility level

wa s gre a t e r tha n that for the straw or bluegrass plots,
A-gain,

the legum es se e m e d to give

additional nit rogen to

the tree in the low fert ili ty plots.

C .■■rrelat1 ■:no

nitro;;on .

m t/Zew. 1 mm wei/. 1hi, ;w,

The percent age o f

,■-...\u.L

w. a

v-2

fro on in 1t\u

close],7 associ ■■i :;d M. tf the ohloro piyll v - _ ...

.

Toe

v ••-•. -

1 at *on bo fcween th e se tw o sabs o p urnt a waa 7e~ yt11>a■ fo r - :<c.•
collecti on ncriod, Table XIII, rang! ng from -1- ' *ny at the
beginning of the season to * C .92 at the one,

:.'hen all of

the data were considered together, the correlnt1rw jas + r#9‘
Thi s ref a tion ship was higher than that found in 19j_7 » which
may bo explained by the fact that the study had continued
for two additional years and ‘he differences in tree vigor
had been somewhat stabilized.
There was soma corral be!on between leaf wo I h t ana

nitrogen when the data were considered for e-’oh collection
period, tho .dues vary in., from + C ..4.7 to +• 1.11.

TL

small

leaves which contained a large amount of nitrogen at the
beginning of the summer, however, reduced the correlations
to

4-

0.31 when ail o ^ she

data

ware considered together.

There was higher correlation between leaf weight and
chlorophyll than between leaf weight and nitrogen.

Trie

values for each collection period ranged from + he 1 to
+ 0 .79, and when all the data were considered together the
value was a 0.9°,
In the lt.,ht cd those correla t ions the chlorophyll
content of the leaf, which can be a relatively siriule uete.riiiin°t ion, would appear to be a fairly accurate Iran. 0 at ton
of the nltroren content of tho led,

The use of chlorophyll

TABLE X I I I

CBEXTTXTIOX
L

SF/F.-JEiiX Lild vrEIOHT, CIILOEO'XIYLL ~?ID
XI THO OE'T IN 1999

Nitrogen and
chlorophyll

!TItno gen and
leaf weight

Chlorophyll and
loaf weight

June 7

0,99

0.6J+

0.99

August 1

0.99

0.97

O.yl

September if

0,92

0.66

0*79

October 1?

0.92

0,60

0.66

0.90

0. 31

0.99

All dat a

de terminations Cor os lima ting luif -Umoies would in oarticulariy accurate for data collected, at any one time.
Loaf weigat would 6ivs some in i Icat icon of tu.j condl 15 on of
the tree, but could not be considered as a substitute for
the nitrogen or chlorophyll determinations,.
Yiel d
Yields, in bushels, from individual trees ware recorded
throughout the duration cf the experiment.

Table XIV gives

the annual, average and total four year yield per free,
tabulated according to fertiliser, mulch and cover crop
tren. tment s, together with a statistical evaluation of the
data.
Since the trees were in very poor condition at the
beginning of the experiment, the yields were exceedingly
low, many trees having little or no fruit on them at all.
This condition existed for three years, the total values
becoming slightly lower ea.cn year.

In the fourth year the

trees had recovered sufficiently to produce a fair crop,
which was significantly higher than those for the other years.
Except for the first year, the yields for all plots
were in relation to the fertility levels, Figure 11A.

The

average accumulated yields were 17o9^» 19*29 and 11,10
bushels per tree for the high, medium and low fertility
plots, respectively*

A statistical analysis of the date,

showed that there was a significant difference, at tne one

TAB LE X I V
ANNUAL

Fertillty
level

Y IE LD

PER T R E E ACCCR jjI N G TC T E E F E R T I L I T Y
L.. j V j L o A N J ' ROUND C0 7LRS

Ground cover

19i*6
(bu.)

191+7
(bu.)

196-8
(bu.)

1969 Tc1a.1
(bu. ) (bu.)

Av 7'•;’e
196'-69
(a,)

High

Pea vine
Bluegrass

1.61
1.32
1-6?
1 .77

1 .86
2.01
i .ig
i .93

1,62
1 .01
1 .Oli
2.2.6

13 •36
12.50
10 ,96
18.?6

19.66
16.36
16.02
19. 71

•-f 1-e
.,.21
8 -70
6. 3

Average

1.69

i

.ij

1 Jj.6

12.68

17 *6-8

6 •36

Pea vine
Straw
Ladino
Bluegrass

I *61

0,7 3 0.63
1 .15

1.32
1.260, 96
0.60

9.12
12.83
8,32
16.08

11.69
10 .76
11.60
19.12

6 iod

2 .16

2,8-9
0.70
2,19

a. 90
1. •
?Vn
a
*i

Average

1 .>1-2

1*6-9

1.02

11. 36 18.29

9.92

Pea vine
Straw
L adino
Bluegrass

1 *76
2.18

0.93

0. 93

I-j .32

13.92
10.26

2. 6

A •36

7.22

3.-9
’ .30

Straw
Lad 5no

Medium

Low

Total

3.69

V

0.81
e.33

■9.67

32

0.73
0.29

Average

2.17

0,62

0.65

7.71

11.17

2.79

Pea vine
Straw

1 .16
1.67
0.86
1.62

l .30
0,92
0.93
1.05

11.18
11,00
9 .3 6
10. 66

17.Oi;
1 f . 36
12 .70
111 .76

3 0 76

3.96

Bluegras s

1. 39
1 .68
2.06
1.76

Average

1.72

1 .89

i .06

10.66

Hi. 71

8 000

1 .

F1e r tili ty

L .S.D.

‘O

1%

0.383
1 ,168

( •'9 O/

P op

0J+.Q

Ladino

All

o,6l

0

0 . ^ 8

11
92
H * J^

Da te

Cover

1.012
l . 3U

1.012
1 . 3ii9

3.62
.69

H i gh

-----

Pea vines

Modi uin--

St ran

Low

Lad ino

Yield

- bushels

Bluegrass

1947

1946

Y e ar
A v er ag e yi eld for each
f er ti li ty level oer year

Figure

11#

1949

Hi gh

M e di urn
Lo w
rertility

Average yield for
mulch and. cover crops
according to fertility
level

Annual yield per tree from 19h'b to 19e-9
ac cording to fertility levels and ground
covers.

percent level,
high

in the

four year average yields between the

and low fe rtility plots,,

There was,

however,

no signi fi­

cant diff er en ce b e t w e e n the yields on the high and medium
levels,
level

and a sig ni fican t difference at only the five percent

betwee n the yields on the mediu m and low fertility

plot s *
during

the first

three years

the yields were so small

that there w e r e no differen ces be tw ee n the values for the
cover and m ul ch treatments*
yields made

In the fourth year,

3ome dif fe renc es evident*

vine plots had the high est yield,
per tree

and the Ladino,

ing all data together,

the higher

The trees in the pea

averaging 11.18 bushels

the lowest,

9.95 bushels.

Co n s i d e r ­

the relatively hig h yields In the

straw clots for the first two years, made the values higher
than those

for pe a vine.

There was,

however,

difference b e t w e e n the values for pea vine,
grass,

The yields

that from straw at

from the Ladino

no statistical

straw or bl u e ­

plots were lower than

the one percent level and from the pea

vine at the five percent level.
The r e l a t i o n s h i p

between the fertility rates

found w h e n all covers were conside red together,
ho l d for the Individual

covers and mulches,

Total yie ld s for the bluegras s
wh i c h

varied d i r ec tl y wi th

plots were

and yields,

did not

Figure lid.

the only ones

the fertility levels.

Those for

straw were h i g h e r in the m edium than in the high fertility
plots and both pea vine and Lad in o plots yielded more fruit

in the low th an in the mo a i vim fertility l^vel,
espe ci al ly bluegrass,
pr o d u c e d

Straw and

w hi ch added no nit ro ge n to the soil,

very small yields

in the low fertility level.

ECO NO MIC AP PL ICATION
The e v a l u a t i o n of a rej uve na ti on pro gran would not be
complete witho ut

a study of the c o s t 3 involved and

financial be ne fi ts

from increa se d returns.

che

Such a study

should be co mp ar ed to the cost of replanting the orchard
plus the lo s s of income during the years when the trees
were

gr ow ing to maturity.
The o p e r a t i n g costs

study v a r i e d ac c o r d i n g
ap pro ximate overall

during the four years of this

to the fe rt ili zer applications.

cost per tree for material and appli­

cat io n of the

sprays was $11.00

vating,

$1.50,

etc.,

This w o u l d be

Thus

p e r i o d w o u l d be $17.50.

the total cost for the fou r-year
The trees In the medium fertility
fertilizer,

so the cost in

be about $15*90.

The ret urn also
Table XV shows

cu lt i­

the cost of the extra f e r t i ­

the additional

those u l o t 3 w o u l d

for pruning,

cost in the low fertility plots.

I n the hig h fer t il it y plots,

plots h a d h a l f

(17);

m a k i n g a total of $12.50 per tree.

the total

l iz er was $5.00.

The

varied with the fertility plots.

the orices paid during the time oi the study

for the va rio us g ra de s of apples and tho average amount
re ceiv ed p e r bushel each year*

The grower thus received

an average of $1.16 per bushel

and paid $0.15 for picking,

l e a v i n g a net of a p p r o x i m a t e l y $1.00 per bushel.

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Considering

the total fo ur -y ear yield,

trees p r o d u c e d 1 1 .1 > bushels
w h i c h w o u l d cause

The high fe rti lity trees

bushels ox e r the same period,
which w o u l d

during the four- year period,

a loss to the gro w er of $ 1.35 per tree

($12.50 - $11.15)*

tree,

the low fertility

u-oduced 1 7 .1+6

giv in g the grower + 1 7 .1+6 per

just about pay

che cost of production.

P r e s u m i n g that the t r e ©3 w o u l d continue to produce
at least as mu c h as in 191-1-9 and that the cost of production
w o u l d be the

same

(one-fourth of tne above figures),

the

trees In the low f e r t il it y plots wo u l d net the grower
a p p r o x i m a t e l y $l+.58 pe r tree per year
$ 3,13 the cost of production)
been absorbed.

(7.71 bu,

or $7*71 -

after the loss of $ 1.35 ha d

On the same basis the

trees in the high

f e r t i l i t y plots w o u l d net the gro wer ap pr ox ima tely $ 8.30
per tree pe r ye a r

($1.2.68 - +I+.3 8 ).

or igi nal costs we r e paid,

Therefore,

after the

the high fertilit y treatment

w o u l d give the g r o w e r approxima tel y $ 3.72 more per tree
tha n the low f e r t i l i t y treatment.
An alternative to re n o v a t i n g an old orchard by the use
of large

amounts of fe r t i l i z e r is to pull out the old trees

and re pla nt
w o u l d be

the orchard.

tree removal

The

expenses to be considered

cost of $ 1 .9-1 (2 6 ), cost of buying

and p l a n t i n g a ne w tree of $ 0 .7 0 , spray costs of $ 0 .$]+ (17)
and fe rt ili zin g,

c u l t i v a t i n g and pruning costs of $ 0 .5 0 ,

m a k i n g a total of a p p r o x i m a t e l y $3*05 per tree for the fourye a r p er iod.

A l t h o u g h the above
they pro v i d e
to follow.

a basis

figures

are quite

approximate,

for de cid in g on the course of action

As p o i n t e d out,

the old ren ovated trees in the

h i g h f e r t i l i t y plots could re t u r n about $8.30 per tree per
year after the f o u r - y e a r period.

In all proba bil ity the

tree w o u l d m a i n t a i n similar pro ductio n for a number of years
and w o u l d b r i n g in a fair income to the grower.
the o r c h a r d w o u l d still consist of old trees,

Nevertheless,

which wo u l d

have to be co n t i n u a l l y forced Into production and eventually
wo u l d ha ve

to be pu l l e d out

and new trees planted.

y oung trees had been pl anted when
they w o u l d have
period,

If the

the experiment started,

been wel l estab lis hed in the four-year

al th ou gh it wo u l d be several more years before

they

w o u l d produce eno ug h fruit to pay for the original cost and
the u pk ee p

duri ng the e ar ly years of growth and give any

pro fit to the grower.

A f t e r 8 to 10 years,

the young trees

w o u l d be p r o d u c i n g as m u c h and probably more
old tr ees

and the

fruit than the

pro duct ion costs would be somewhat lower.

T h e n the o rch ar di st wo u l d realize more profit on the young
trees

thav.

n th-. i I

The eco no mic

aspects of rejuvenation,

d ep en d on the financial
ess en ti al

'*

req uir ements

therefore,

of the grower.

that he m a i n t a i n his immediate earnings,

n a t i o n p r o g r a m w o u l d be advisable.

If,

would
If it is

a re j u v e ­

on the other hand,

he is in a p o s i t i o n to forgo

some of bus immediate income

and fo l l o w a long term plan,

a tree removal

and replanting

p r o g r a m should e v e n t u a l l y lead to greater profits.

DISCUS SI ON
All the r e su lt s

d e s c r ib ed in detail in the foregoing

sections poin t to the fact

that the positive and definite

r e j u v e n a t i n g effects ob taine d from the use of fertilizers
were In r e l a t i o n
somewhat

to the amount of fer til izer used. To

l e s s e r extent,

a

improvements in tree vigor and

yield ixere also o b t a i n e d from the use of mulches and cover
crops.

I n ad d i t i o n to these clear-cut results,

several

i n t e r - r e l a t i o n s h i p s wh ic h should be pointed out.

As the tree absorbs nutrients,
In the ve geta t i v e parts,
and shoots.

there were

the first response

which Include the leaves,

is usually
trunk

3y me ans of this growt h there is an acc um u­

l a t i o n of storage mat eri al

in the tree which wi ll eventually

p r odu ce new a x i ll ary buds.

Since it takes two years to pr o ­

duce' a b l o s s o m from an axillary bud,

the effects of f e r t i ­

lize rs c o u l d h a r d l y be expect ed to influence fruit production
for at least

two years.

The results of this

study clearly

showed this time relationship.
One
of cover

of the ea rli est responses to fertilizers was that
crops, w h i c h showed a differential

after the L adino
crops

are

efj.©ct In

plots had been established.

surface r oo te d as compared to trees,

19$7*

Since cover
they w ou ld

be e x p e c t e d to r e s p o n d to large applicatIons of fertilizer
in a r e l a t i v e l y short

time.

The fact that there was little

d if f e r e n c e

in cover crop

medium fertility

growth b e t we en the high and the

plots but conside ra ble

difference between

the m e d i u m and low olots for bo th Ladino and bluegrass,
showed

the ne ed for pho sp no ru s and potash in

plots.

The hi g h and me d i u m

tai ned both p h o s ph or us
a pp li ca t i o n s
nitrogen,

fertiliser applications con­

and potash,

contained neither.

were

the cover crop

while

the low fertilizer

These elements,

there Tore nee ded for adequate

as well

as

cover crop

growth.
C o n s i d e r i n g the growth of the tree itself,
cross

sectional

the trunk

area and shoot gr o w t h responded to the

f e r t i l i z e r tre atments at different times.

The percentage

increa se

response in the

in trunk area showed an immediate

first year,

the values being proportional

f e r t i l i z e r applied.
m e a s u r e m e n t s we r e
l i z e r applied,

not

At the same time,

the shoot growth

proportional to the amount of ferti­

but were app are nt ly influenced by the original

co nd it ion of the trees.

After the se co nd year,

showed the same pro port io na l
actual

to the amount of

do wnward

relationship,

trend was not

although

was

years of

very small,

able

and 9.

In the

the experiment whe n the shoot growth

the perc en ta ge increase in trunk area in

each f e r t i l i t y level
Figures

the

checked until 19^4-9, when

re co ve ry of shoot grow th was reall y apparent.
first three

shoot growth

continu ed at about the same rate,

I n t h 9 final

year,

when

shoot grow th on each fer tili ty level,

there was

conside r­

the trunk area

increase was smaller than In the previous years.
By the second year, 1947, the leaves of the trees had
also responded in proportion to the fertilizer applications.
Mean figures for dried weight cf the loaves and for their
chlorophyll and nitrogen content all showed this relation­
When these values were compared with one another,

ship,

only total nitrogen

and leaf weight were found to

oe statis­

tically

correlated.

In 1949, data again showed that leaf

weight,

chlorophyll ann nitrogen values responded

portion

to the amounts of fertilizer used, but to an even

g r e a t e r exte nt than in 1947.

in pro­

In 1949, the correlation

between total nitrogen and chlorophyll was 0.90 "cr all
data together, and thus was more sipnif icam: than in 1947 •
Cornels,tion between total nitrogen and leaf weight was
about t h e s ane as for 1947 at the s ame samcling period©
The relationship between leaf weight and chiorophyli was
greater in 1949 than in 1947 but still was not statistically
significant.
A comparison of the actual values for loaf analyses in
1947 with those for 1949 showed that all the frees had Im­
proved In vigor with the various treatments.

The dry weight

of the leaves was much greater at the latter date.

The aver

value for the low fertility in 1949» 200*0 mg. per leaf, was
higher than the average value for the high tertility level
In 1947 , 139*3 mg. per leaf.

The chlorophyll content per

square centimeter was approximately the same In the two

years., but since the leaven
c hl or ophyll

con bant of the leaves was larger,

the pe rc enta ge

of ni trog en

c o n s i d e r a b l y above
pe r c entage

were larger in l rd|9,

that In 199-7*

The

As with leaf weight,

the

for the low fertility plots in i rhfg

of n i t r o g e n

plots

In 191+9,

for each fertility level 'was

wa s h i g h e r than the per centage
fertility

the total

of ni tr ogen in the high

in 191+7*

i n c reas ed percenta ge ni tr og en together with the

I n c re ased le af size ac c e n t u a t e d the total

amount of nitrogen

per leaf and conse qu e n t l y the differences

between treatments.

Final.ly in 191-1-9* yield r e s pon de d to
treatment.

The light

the fertilizer

crop in the first three years of the

experime nt made It Impossible to detect yield differences
du r i n g this

early period.

direc tl y re la te d to the

The hi ghe r .yields in 191+9 were

amounts of fert ilize r used.

the sarne ye a r and in all fertility levels,
i n c r e a s e d more than
while

in any previous

the pe rc ent age

Tor any p r e vio us
emphasize

year

In

snoot growth

year in the experiment,

increase in trunk area was smaller than
since 191+6.

These data serve to

the in te r- re l a t i o n s h i p between the various parts

of the tree and their effect on tree performance.
W h e n the va ri ou s

covers were

there were appare nt d is cr ep anc ies
f e r t i l i t y plots.
careful

in yields

These may be explained,

c om p a r i s o n wi th shoot

analyses.

considered separately,

growth,

from the three

in part,

by a

trunk area and leaf

The i n c r e a s e d yield from the bluegrass and straw

in the m e d i u m fe rtili ty plots,
may be a s s o c i a t e d w i t h

as sho,/n in Figure 111,

the h ighe r increase

acc o r d i n g to Figure 5>R, and

in trank srca,

the hig he r actual

as shown in Table IV and Figure I4.C.
grovJth and trunk ar ea increase may

shoot growth,

This larger shoot
in turn be associated

w i t h the r e l a t i v e l y l arg er leaf weights

and. the higher

amounts of nit r o g e n found In the leaves from these p l o t s 0
There was

9 similar relati onshi p for the La dino and

e s p e ci al ly for pea vine treatments
plots*
plots

in the low fertility

Y i e l d wa s h i g h e r than in the straw and bluegrass
and ma y have been related to the higher percentage

trunk area increas e

and higher actual

snoot growth.

These

values m a y also be a s s o ci at ed w i t h the great er weight and
n i t r o g e n content of the leaves*
A m o n g the mu lc h and cover crop treatments,
were

o u t s t a n d i n g in their effect on tree performance.

m u l c h i n g ma t e r i a l
shoot

was mu c h more
plots.

This

pro duced the greatest average value for

growth and trunk area increase

l e a f weight,

than

pea vines

chlo rop hyll

and nitrogen

as well as the largest
values.

This effect

apparent in the low than in the high fertility

Lad i n o was less eff ective than pea vines,

straw or b lu e g r a s s

but better

in inc reas ing these measurements

in the 1 ow f e r t i 1 i ty plot s .
A fur ther im pro veme nt
tree wa s

shown by

In the general

condition of the

the great er leaf weight

found in 19^9 as

c o m p a r e d to that in 19l|7.

This improvement,

however,

was

'J

not

the

came for all mulches

ortil._z©r lc vol

j as

Siiown in Ta /I© XVI »

plots p r o d u c e d the largest
per leaf,
grass,

and cover .n’ops,

increase

as c o m p a r e d to 103,0,

La d i n o

and straw plots,

also m a i n t a i n e d this increase
f e r t i l i z e r levels,

39.1

ncr for all

Tin© pea ’/in©

of leaf weight,

13.
1 *9 mg.

and 33,9 for the olue-

respectively.

The pea vines

in leaf weighs, at the three

ind icating that tais mulching material

h a d a de c i d e d effect on leaf weight increase at all three
levels of fertility.
I n c o n s i d e r i n g the overall picture/,
Is the effect
and vigor of
noted,

that

of utmost importance

the various treatments had on the health

the leaves.

The dry weight,

as previously

ha d incr ea se d on each fertility level in 193-9, being

almost twice

as heavy as they ha d been in 199?’.

In each of

these two years the chlorophyll per square centimeter remained
approx im at el y the

same, v a r y i n g only in relation to the

fe r t i l i t y level.

The percentage of nitrogen in the leaves,

on the other hand,

was higher on each fertility level in

19]p9 than It had oeen in 1937*
of ni t r o g e n

Therefore,

the total amount

in each of the heavier leaves was considerably

g r e a t e r in 1939 than In 1937.

These facts all indicate

that the c o n d i t i o n of the leaves had made a aecided improve­
ment.

As a result of this general improvement in the leaves

after fo ur ye ars of con tinuo us heavy feeding,
of the whole tree ha d started to improve.
h a d I n c r e a s e d and the terminal

the condition

The trunk area

growth was greater.

Thus the

TAB LE X V I

L E A F W E I G H T I N C R E A S E FROM 1 9i-l7 TO 19^9 W IT HI N THE
D IF FE RE NT F ER TILITY LEVELS A N D GROUND COVERS
Weight per leaf
Fe rtility Itivel
High
Me dium
( m g ,)
(n g . )

Low
(m g * )

1^3* 0

133.9

11+7.6

99.3

99.0

67.2

ITS
•
CO
CO

L adino

119,1

83.9

69.3

39.1

B lu eg ra ss

1 3U .0

101 ,7

89.3

103.0

122,9

101+.^

92,0

G r o u n d co ver

Pea vine

S tr aw

Average

Average

1 4 1 . .?

trees h a d rec ov ered s u f fi ci ently
in 191+9 and to co nt inue

to produce

their improvement

setter yields

in future years.

SUMMARY
Treatments which were designed to rejuvenate an old
apple orchard included

the use of three rates of fertilizer

applications which crossed over straw and pea vine mulch
plots and Ladino and bluegrass cover crop plots.

Results

were recorded in the field by means of shoot growth,
circumference and yield of the trees,
cover crops.

In the laboratory,

trunk

and by weights of the

dry weight and chlorophyll

and nitrogen content of the leaves were determined.
The higher fertilizer applications were effective in
increasing trunk area,

cover crop ’weights, leaf weight,

nitrogen and chlorophyll content of the leaves,
and finally yield,

shoot growth

in that relative order*

The effects on growth were in proportion to the amounts
of fertilizer used.
The Increase In leaf weight, leaf nitrogen and chloro­
phyll stimulated tree growth which in turn Increased yield.
Among the mulch and cover crop treatments,

pea vines

were outstanding in their beneficial effect on tree perform­
ance.

This effect was more apparent in the low than in the

medium or high fertility plots.
A program of rejuvenation as conducted under the con­
ditions of this experiment, would give temporary economic
benefits.

Over a long period of time, however,

a tree

removal and replanting program might be more profitable.

LITERATURE CITED

1*

Ano nymous.

1922*

B r in gi ng back

F a r m e r s 1 A dv oca te
2.

3.

A. 0. A.

C, 1914-3*

57:31+1*
Official

and tentative methods of

analyses.

A ss oc iati on of Official

Chemists.

Washington,

Ballou,

F. H. 1916,

eastern Ohio.
Bull.

D.O,

O r c h a r d rejuvenati on in So ut h­

Ohio Agricultural

_. 1920.
Ohio.

Agricultural

Experiment Station

301.

1+.

3.

the old apple orchard*

Orc hard rej uve na ti on in Southeastern

Ohio Agr icul tu ra l Experiment Station lull.

____________ .
In d us tr y

192 9.

339*

Rej uv enat io n of the apple growing

in S o u th ea stern Ohio,

In di ana Hort.

3oc,

for 1921+:8l-97 *
6.

Boon,

G. C. 1919*

Chron.
7.
8.

Burkholder,

C. L . 1952,

Catchpole, N. 191+6.

Compton.

Gard.

Arner, 23:1+2-1) 3»

Ama te ur Gard.
9.

Res to ring an old orchard.

No.

Personal

communication.

The treatment of neglected orchards.
3259,

n, 10.

0. C. and Damon Boynton.

191+5*

A rapid method

for the d et er mi n a t i o n of chlorophyll in apple leaves.
Prcc • Arner.
10.

Soc. Hort,

Gox, H. R. 1917*

S c i . 1+6:1+5-59.

Co untry Gent. 82:22.

Jour, Agric, (New Zealand) I4I;:38-3-3^4-9.

11.

Davey, M. 1932.

12,

Davis, M. P* 1914*

Dominion of Canada, Dept, of

Agriculture Dominion Experimental Farms Bull. 79:
1-32.
lg.

Ellenwood, G, W. 199-3*

The home apple orchard,

Ohio

Agricultural Experiment Station Bull. 28 (22G):13-l6.
Ill*
15>.

. 195>2.
Fletcher, S. W. 1982.

Personal correspondence.
The history of Pennsylvania

Agriculture, Vol. 2•
16.

Go ul d , h . P. 1922.

U.S. D.A. F a r m e r s ’ Bull. 1289.

17.

Lewi s , j'« H. 1980.

Oral

18.

Mack,

19.

Mason,

vV . f
c. 1982.

A . P. 192p.

c omniun i c a ti 011.

Oral commund 0 a ;m r ■.,
Renovation of old apole orchards0

New Jersey Agricultural Extension Bull. 39c
20.

Oakes, Ohas.

. 1911.

Rejuvenation of an old orchard.

Ohio State Port. Soe. /;9_:11-12.
21.

Razor, Coleman, 1918,

Orchard rejuvenation,,

Kentucky

Bureau of Agriculture, Labor and Statistics.

22nd

Biennial Rr-t. for 1916-191 7 :9.60-9-69 .
22.

Robinson,

, G. 1918.

Orohainl renovation.

Maine

Agrid, repi, Bv. 17:71-6s.
23.

Sears, P. C. 1918.

Renovating old apple orchard.

Country Gent, 83:10-11,
2lp#

. 1921.

Renovating old orchards.

Dept, of Agriculture.

Dept. Bull.

lQ:l-19«

Mass.

( O

29.

Thurston,
back„

26.

Varian,

H . F. 1916.

B r i n g i n g a n e g l e ct ed orcha rd

Fruit Gr o s e r 27: 1 8 ,
K e n n e t h K. 193-7*

Cost of removing.

wi bt b u l l d o z i n g out old apple
A s s ’n. of Pa.
27.

Wilcox,

J.

State llcrt.

News 2?lp(3) :11 - 1 8 *

C, 1937.

and fruiting. I.
shoots.

trees.

Exp erience

Field, studies of apol e tree growth
Sa mpl in g and m e a s u r i n g terminal

S c i . A eric.

17(9):863-872.