THE EFFECT OF HEIGHT AND
FREQUENCY OF CUTTING ALFALFA
UPON ITS GROWTH AND ROOT
DEVELOPMENT

Thesis for the Degree of M. S.

MICHIGAN STATE COLLEGE
Stuart C. HiIdebrand
I938

5-.

'1' ,
‘;

 

THE EFFECT OF HEIGHT AND FREQUENCY OF CUTTING ALFALFA
UPON ITS GROW AND ROOT DEVEOPMENT

THE EFFECT OF HEIGHT AND FREQUENCY OF CUTTING ALFALFA
UPON ITS GROWTH AND ROOT DEVELOPMENT

Thesis

Reapectively submitted in partial fulfillment of the

requirements for the degree of Master of Science

at

Michigan State College
of
Agriculture and Applied Science

Stuart C. Hild brand
Farm.0rqps

1958

ACKNOWLED GMEN T

The writer wishes to eXpress his appre-
ciation to Dr. C. M; Harrison for his constructive
criticism.and helpful advice in the preparation or
this thesis. Appreciation is also due Professors
c. R.‘Megee and.Hs 0. Rather for their assistance

in its final reviete

I.
II.
III.

V.
VI.
VII.

TABLE OF CONTENTS

INTRODUCTION

REVIEW OF LITERATURE
EXPERIMENTAL PROCEDURE
EXPERIMENTAL RESULTS

A. Effect of Cutting Alfalfa Upon
Yield of Top Growth

B. measuring the Root Reserves or
Alfalfa

DISCUSSION
CONCLUSIONS
BIBLIOGRAPHY

13
20
22
23

 

INTRODUCTION

Alfalfa, in the past few years, has proven itself
to be Michigan's most valuable and dependable forage crop.
Statistics show that the alfalfa acreage in Michigan has in-
creased from 575,000 acres in 1930 to 1,105,000 acres in 1937.
One of the important uses of alfalfa in Michigan is as a pas-
ture crop during the months of July and August. During this
period conditions of high temperature and low rainfall usually
prevail and native bluegrass pastures are largely dry and dor-
mant.

EIpertments conducted at the Michigan Experiment
Station at East Lansing, Michigan and outlying sub-stations
show that alfalfa or a.mixture of alfalfa and smooth brome
grass, because of the drought resistance of these plants,
sill furnish.more green feed during the hot summer months
than any other pasture canbination of perennial plants yet
tried.

The value of a pasture crop is measured by its pal-
atability, composition, yield, and permanence. Alfalfa has
proven itself to be highly productive, palatable, nutritious,
and fairly permanent if proper management practices are follow-
ed. Research has shown that cutting at immature stages of

growth increases the protein content of the feed, but such

practices may result not only in severe damage to the stand,
but in a reduction of the amount of new growth produced.

Emperimental results indicate that close grazing
tends to exhaust the food reserves in the roots, thereby
reducing the vigor of the alfalfa plants. It has been recomp
mended that alfalfa be pastured off to an 8 to 10 inch level
during the pasture season. By proper stocking and good man-
agement.practices it is possible to maintain an alfalfa field
at a given level of height growth. There is also the possi-‘
bility that alfalfa.may be pastured off to a lower level than
8 to 10 inches without injury to the stand, either with re-
gards to its vigor in the summer or winterkilling.

It is the object of this experiment tostudy the
effect of the height and frequency of cutting alfalfa in the
greenhouse upon its yield and root development. Cultures of
alfalfa plants were cut back to 1 inch, 3 inches, 6 inches,

9 inches, and 13 inches at weekly, bi-weekly, and.monthly
intervals for twelve successive weeks. Following this all
cultures were completely defoliated for four successive weeks
and then allowed to recover for two weeks at which time the
cultures were washed free of the sand in the pots. It is hoped
that some information may be obtained.which will further in-
dicate the practices to follow in the proper management of al-

falfa.

REVIEW OF'LITERATURE

many studies have been made concerning the effect
of the time and number of cuttings to make, heavy and light
grazing, and rotational and continuous grazing upon the yield,
chemical composition, and storage of food reserves in the
roots of forage plants and weeds. However, very little work
has been done on the comparative effect of height and fre-
quency of cutting alfalfa upon the yield of tops and root
development.

Weaver (10) of Nebraska, in his work with roots
found that there is a high correlation between the growth
and development of roots and tops of plants.

Graber et al (3) working in Wisconsin with alfalfa,
alfalfa and timothy, Kentucky bluegrass, and red top found
that the productivity and vigor of these perennial plants was
greatly reduced, encroachment of weeds favored, and both
summer and winter damage to the stand accelerated by frequent
cutting at immature stages of growth, over a period of five
years. He came to the conclusion that the depletion of food
reserves was primarily responsible. He observed also that,
for the most part, storage of food reserves occurs between

blossoming time and the seed stage.

Granfield (4) with pasture weeds; Sprague (9)
with bent grasses and Kentucky bluegrass; Willard (ll) and
Nelson (s) with alfalfa; Albert (1) with Kentucky bluegrass,
red top, and alfalfa; and Kiesselbach and Anderson (6) with
alfalfa, substantiate the work of Graber.

Graber (z) in his studies at Wisconsin concerning
the food reserves in pasture plants found that heavy grazing
reduced the food reserves and root and rhizome growth of blue-
grass so much that white grubworms ruined the stand. Where
Judicious grazing was practiced very little damage resulted.
In the greenhouse, Kentucky bluegrass and red top, under
controlled conditions for a period of two months after seed-
ing, produced seven to eighteen times as much root growth
where the plants were not clipped as where seven clippings
were made.

Harrison (5) in his greenhouse studies with Kentucky
bluegrass at the university of Chicago found that frequent
and close clipping reduced the yield of tops and tended to
weaken the roots and rhizomes.

Leukel et al (7) of Florida, carried out some ex-
periments with pasture grasses and found that frequent cutting
of bahia, carpet, and centipede grasses, all of which are pro-
cumbent, kept them in a vegetative state and produced a denser,

more desirable sod. 0n the other hand, frequent cutting of

sudan grass reduced the yield and finally resulted in a total

loss of the stand.
III. EXPERIMENTAL PROCEDURE

The preliminary work on this experiment was begun
in September 1937. Several hundred Hardigan alfalfa plants
were dug from.a one-year old alfalfa field. These plants
were brought into the greenhouse and selected for uniformity,
after which the soil was washed from the roots and the plants
transplanted into sand cultures in 10 inch clay pots, eight
plants per pot. The tops were all cut back to approximately
two inches. By frequent watering and the application of a
complete nutrient solution at regular intervals the plants
were kept growing until April 1938. Because of poor light
conditions at East Lansing during the winter it is difficult
to keep the plants vigorous and any amount of cutting would
have resulted in severe damage. Insect injury during the
‘winter, which resulted in death to some of the phants, neces-
sitated their replacement with live once in Merch 1938.

on April 13, 1938 the cultures were selected at
random for use under the various cutting treatments. They
were arranged in five sets of nine cultures each, to be cut
back to 1 inch, 3 inches, 6 inches, 9 inches, and 12 inches,
respectively; three of each of the sets of nine cultures were

cut at weekly, three at bi-weekly, and three at monthly inter-

-5-

vale. In addition, nine cultures were selected as final
check plants and three selected as representative of the
group of cultures to show the condition of the plants at
the beginning of the experiment. The cultures were not ran-
domized for rows or columns because of a shading factor and
because it was desirable to approach field conditions as
closely as possible. From this point onward until the end
of the experiment the cultures were watered daily if necessary
and applications of a complete nutrient solution made weekly.
After the cultures were properly arranged they were
cut for a period of twelve successive weeks, at weekly, bi-
weekly and monthly intervals, back to 1 inch, 3 inches, 6
inches, 9 inches, and 12 inches from the sand, the checks
being left uncut. At the end of the twelve weeks period all
cultures, including the checks, were completely defoliated
for four successive weeks in an attempt to measure the root
storage by the amounts of recovery growth between cuttings,
at the various cutting heights and intervals. Directly after
each cutting treatment green and dry weights were taken for
each culture. The cultures were allowed to recover for two
weeks, pictures taken, the sand washed from the roots of the
cultures, and pictures taken again. The tops and roots were
separated, put into labeled bags,and green and dry weights

taken for each culture under each treatment.

In order to secure the weight of roots free from
sand, the following procedure was develOped. The dry roots
were broken into small pieces in a pail of water, the pieces
floated off, and the remaining sand dried and weighed. The
weight of the sand secured subtracted from the original dry
weight of the roots gives the weights of roots free from.sand.
Upon ashing several root samples and calculating the amount of
sand present, it was concluded that the method removed all ex-

cept approximately one per cent of the sand.
IV. EXPERIMENTAL RESULTS

To show the condition of the plants at the beginning
of the experiment, pictures were taken of the three cultures
selected at random, before and after washing the roots free
from sand,(Figure I) The roots and tops were separated and
green and dry weights taken for each culture and recorded in
Table I.

TABLE I.

THE YIELD OF TOPS AND ROOTS OF ALFALFA PLANTS BEFORE CUTTING
TREA WERE BEGUN

Culture ~ ' " Reots
Number an s

Ems.

Ems.
116.70 27.45
90.80 26.45
128 45 28.40

 

-8-

 

 

FIGURE I.

ALFALFA CULTURES AT THE BEGINNING OF THE EXPERIMENT
April 1958

Above - before washing sand from roots
Below - the same plants after washing sand from roots

-9-

A. THE EFFECT OF CUTTING ALFALFA UPON THE YIELD OF TOP GROWTH
The comparable effect of cutting cultures of a1-
falfa back to heights ofgl inch, 3 inches, 6 inches, 9 inches,
(a).(b).
and (c) for weekly, bi-weekly, and.monthly cutting intervals,

and 12 inches upon the yield is shown in Table II.

respectively.
TABLE II. (a)
THE EFFECT OF WEEKLY CUTTINGS AT'VARIOUS HEIGHTS UPON THE YIELD

OF DRY MATTER OF ALFALEA
jAyerage of three cultures)

 

 

 

 

 

 

 

 

 

 

I Date of Cuttin: Bei t of Cutting Checks - Av.
of nine
1938 1' 3" 6" 9' 12' cultures
me Me was Me Me 81118.
April 18 17.00 19.00 13.33 9.00 5.17 I
23 i.25 1.64 0.93 0.51 0.39 ,
30 .34 2.45 1.93 0.60 0.44 5
May fl e e e I.39 'e; i
14 0.68 1.50 1.81 1.00 1.20
21 0.64 0.77 1.40 1.43 1.39
28 1.05 1.69 2.45 2.23 2.23
IMO ‘ 'g . 2.25 . .s ‘
11 0.64 2.53 3.28 3.26 1.70
18 0.37 3.18 3.69 3.51 4.70
25 0.51 2.86 2.57 1.78 2.35
I I ’ .e' e 5066 503’ is.
¢ 9 2.94 19.40 37.50 54.30 72.50 79.55
0 3 I Q ' 1'e’ e 78e1‘ e 'TeI' e
‘ "ecoveryi
growth.made a-
bove cutting '
level. 9.09 24.67 27.31 21.71 21.92

 

 

 

 

 

 

 

 

The weights given on.April 18 are the yields in dry
matter of the initial cutting at the indicated height. The
weights on July 9 are the yields in dry matter for the various
cultures when the height of cutting was discontinued and all
plants were completely defoliated.

When one considers the total yield, the cultures
cut back to 1 inch are far below the total production from
the cultures cut at any of the higher levels. Although large
differences exist between the other cultures, all of them.com-
pare rather favorably with the checks. One distinguishing
point can be seen in that the cultures cut back to the 6 inch,
9 inch.and 12 inch levels, produced less the first few weeks
of the cutting treatment, but afterwards outyielded the 1 inch
and 3 inch cultures. This is especially noticeable in case of
the 1 inch cultures. Not only did the yields decrease, but
the vigor of the plants was reduced. In the case of the 9 inch
and 12 inch cultures the cutting treatment at first caused a
denser growth, while in the cuttings at lower levels, the ef-
fect was to produce upright stalks.

The last line in Table II (a) is the total amount
of dry matter produced above the various levels of cutting;
the April 18 and July 9 yields being disregarded. Considering
the results from this point of view there is still a large
difference between the 1 inch and the higher levels of cutting.

Considering the total yields in Table II (b) there
are still large differences between the 1 inch and 3 inch, and
the 6 inch, 9 inch, and 12 inch levels of cutting. However, if
Table II (a) is referred to it will be found that the differences
are not so great when the cutting was made at intervals of two

weeks in comparison to intervals of one week. 'When considering

-11-

TABLE II (b)

THE EFFECT OF BITEEKLY CUTTINGS AT VARIOUS HEIGHTS UPON THE
YIELD OF DRY MATTER OF ALFALFA
average of three cultures)

 

 

 

 

Date offigutting Hei'ht of Cuttin hecks(aver.
*7 f nine
._ 1938 fij, 3" 6" 9" 12" ultures)

 

Ems. gms. ng. gms.
17.50 14.00 9.17 4.07
3.56 4.03 2.82 1.36

 

2:77 3.97 3:81 3:22

 

 

 

 

 

 

 

 

 

 

 

 

 

5. 8005 7048 O

.83 7.73 5.37 6.83

tam. WW. . 79.53
”611429I.I 9'. . .

growth.made a-

bove cutting - I -

level 18.22 22.39 28.36 23.23 20.76

 

 

 

V—v v—r

the'recovery" growth made above the cutting level the 6 inch
cutting treatment gave the highest yield. It is noticeable
here also that the differences are not so great between the
cultures cut to 1 inch and the cultures cut to higher levels
as under the weekly interval. However, the results indicate
that the 1 inch cultures were damaged considerably by the
cutting treatment.

Table II (0) gives the yields under the monthly in-
terval of cutting. As in the case of the weekly and biweekly
intervals the total yields of the cultures increase with the
height of the cutting treatment but only up to 9 inches in
this case. A great change can be noticed in the ”recovery“
growth made above the cutting level, the 1 inch culture giv-
ing the highest yields and the 12 inch cultures the lowest.

-12-

TABLE II (c)

THE EFFECT OF MONTHLY CUTTING AT VARIOUS HEIGHTS UPON THE
YIELD OF DRY MATTER OF ALF

of nine

.67 .67
12.87 15.37 10.50

14.23 11.07 14.75

growth made
above cutting

 

Table III is a summary of the total yields of top
growth obtained along with the 'recovery" growth made above
the cutting level for weekly, biweekly and monthly intervals.

TABLE III

Weekly .03 .07 .14 .01 .59
Total Yield Biweekly .39 64.42 91.19 96.33 102.40

growth made Weekly 9.09 24.67 27.31 21.71 21.92
above cutting Biweekly .22 22.39 28.36 23.23 20.76

 

The total yields increase from the 1 inch to the 12
inch cultures and from the weekly to the monthly intervals ex-
cept in the case of the 12 inch cultures cut monthly.

In the "recovery" growth made above the cutting level
the 6 inch cultures led in production but the differences be-
tween the 3 inch, 6 inch, and 9 inch cultures are small. The

1 inch cultures fall below the others except when out at
monthly intervals.

As to the 12 inch cultures, the total yield dropped
under the monthly interval because of the maturity of the plants.
At such a wide interval there was an abundance of seed pods
formed. The same reason holds true for its failure to show a
satisfactory yield under the "recovery" growth made above the
cutting level.

Figure II shows the "recovery” growth for each height
of cutting at weekly, biweekly and.monthly intervals, graphi-
sally.

B. MEASURING THE FOOD RESERVES IN THE ROOTS 0F ALFALFA

The method employed to determine food storage was
to defoliate the plants in each culture completely and to
measure the reaponse in terms of top growth and finally, at
the end of the experiment, to secure the weights of the roots
in each culture treatment.

After making complete defoliation for four successive
weeks, the cultures were allowed to recover for two weeks. At
this time pictures were taken, the roots of the cultures washed
free from sand, and pictures taken again. Theznots and tops
were separated and green and dry weights taken for each culture

and recorded in Table IV.

(0?” Oz ,09 sztha HZuODu (r3 2. G .rl.dn

 

-15-

TABLE IV

DRY.MATTER IN ROOTS AT THE END OF THE EXPERIMENT
average of three cultures)

  
   

 

 

   

 

 

 

 

 

 

 

n erval
Previous treatment ‘Biweekly Mbnthlz '
gms. gms.
Cut back to 1" 5.21 11.09
" 7 " 3” 13.21 18.24
" 7 " 6”, 17.14 20.00
7 7 ” 9" 24.16 33.79
" " " 12" 30.64 38.88
TChecks (no pretIous
treatment)» 41.52

 

 

 

The above table shows that as the height of cutting
was increased the weight of roots increased. At the same time
the weight of roots increased from the cultures cut at weekly
to those out at monthly intervals, with the exception of the
12 inch cultures.

The responses from complete defoliation on successive
weeks in the form.of yields of top growth gives further infor-
mation as to the effect of cutting upon root reserves. (Table
V.) This table shows that there is a definite relationship be-
tween the height of the cutting treatment and the storage of
food reserves as indicated by the growth response after complete
defoliations. There is a definite upward trend from the 1 inch
cultures to the checks, with one or two exceptions. The same
statement holds true, in general, for the weekly to monthly
cutting intervals; the wider the interval, the greater the
response.

The 1 inch cultures suffered severely from the complete
defoliations, those out back weekly dying about July 30 after
two defoliations and those out biweekly about August 6 after

~16-

TAELE V

RESPONSE IN DRY MATTER AFTER ALFALFA WAS COMPLETELY DEFOLIATED
_javerage of three culturesl_

 

 

 

 

 

 

 

 

    

 

    

 

   
 

 
 

 

 

 

 

 
  

 

a e e- in- Bfevious treatment :IMecksfiIno
‘ foliated terval Cut back to
: ' I "‘6'—
gms. gms. gms. gms.
~ Weekly 0.06 1.12 1.82 2.56
July 16 Biweekly 0.32 0.91 1.58 2.07
Monthly' 1.36 1.56 1.62 3.23
Weekly 0.01 1.35 2.12 3.95
23 Biweekly 0.26 1.55 2.03 4.00
Monthly 1.81 2.76 3.40 4.57
Weekly . . . 2.70
30 Biweekly 0.03 0.88 1.60 2.93
Monthl 0.92 1,73 1.87 3.77
Wee y . 0.55' 0.49 I}64
Aug. 6 Biweekly 0.00 0 058 0 086 1061
0.49 0.91 1.18 1.73
‘ y 0.00 0.97 0.37 O
20 Biweekly 0.00 2.77 1.98 6.30
Monthly_ 1.17 3.13 3.87 10.27

 

 

IL

 

 

 

 

 

 

 

 

three de

IT'

foliations.

Those cut back monthly did not die.

The

3 inch cultures cut weekly and biweekly also suffered severely

from.the treatment but did not die.

monthly gave fair yields.

The 3 inch cultures out

By comparison, the 9 inch and 12 inch cultures gave

the greatest response with the 6 inch cultures being slightly

lower.

The 1 inch and 3 inch cultures fall far behind.

The condition of the roots and tops of the cultures,

after being completely defoliated for four successive weeks

and then allowed to recover for two weeks, is shown in Figures

III, I7, and V for weekly, biweekly, and monthly cutting in-

tervals, reapectively.

 

 

FIGURE III.

GROWTH RESPONSE AND CONDITION OF ROOTS
(August 1938)

Upper: Growth response after two weeks following four suc-
cessive complete defoliations of a set of cultures cut back
weekly for twelve successive weeks to the indicated height.

Lower: The same cultures showing the root development after
the roots were washed free from sand.

Reading left to right: check, 12 inch, 9 inch, 6 inch, 3 inch,
and 1 inch cultures.

Note the lack of root development of the 1 inch, 3 inch, and

6 inch cultures along with the dead roots present. The 9 inch
12 inch, and check cultures have good healthy root systems al-
though the 9 inch is decidedly smaller than the other two.

 

 

 

FIGURE 1‘.

GROWTH RESPONSE AND CONDITION OF ROOTS
(August 1938)

Upper: Growth response after two weeks following four suc-
cessive complete defoliations of a set of cultures cut back
biweekly for twelve successive weeks to the indicate height.

Lower: The same cultures showing root development after
the roots were washed free from sand.

Reading left to right: check, 12 inch, 9 inch, 6 inch, 3 inch,
and 1 inch cultures.

Note the lack of response of the 1 inch culture and the small
response of the 3 inch. The 6 inch and 9 inch cultures show
medium response but are not comparable with that made by the
12 inch and check cultures. The same general statements hold
true for the roots the roots of the 1 inch being dead end the
3 inch culture having some dead roots.

 

FIGURE V.

GROWTH RESPONSE AND CONDITION or ROOTS
(August 1938)

Upper: Growth response after two weeks following four suc-
cessive complete defoliations of a set of cultures cut back
monthly for twelve successive weeks to the indicated height.

Lower: The same cultures showing root development after the
roots were washed free from sand.

Reading left to right: check, 12 inch, 9 inch, 6 inch, 3 inch,
and 1 inch cultures.

Small responses were made by the 1 inch, 3 inch, and 6 inch
cultures which do not compare favorably with the cultures cut
at higher levels. The same is true for the roots. Note the
dead roots in the 1 inch, 3 inch, and 6 inch cultures espec—
ially the 1 inch. The 9 inch, 12 inch, and checks cultures
hhow well developed root systems. There is no logical reason
as to why the 9 inch is larger than the 12 inch culture.

V. DISCUSSION

The amount of "recovery" growth following complete
defoliation of the cultures cut at various intensities was
used as a measure of comparative root storage rather than
chemical analysis.

In using the "recovery" reSponse method the re-
serves can be measured in the form of dry matter yields of
tops. Naturally, under such conditions each material con-
cerned in the reserves must assert itself to bring about new
growth. Under these conditions it is not necessary to know
what materials go into root storage.

Carbohydrate food storage in the roots of alfalfa
plants depends primarily upon the top growth. As carbohydrate
materials are manufactured through photosynthesis they are
either utilized by the growing plant in producing new plant
parts or are stored for future use. As the plants mature,
growth processes slow up and more materials are manufactured
than needed, the surplus being stored in the roots.

Plants kept growing with a small amount of leaf tissue
will result in a small root system.because there is a high cor-
relation between top and root growth. It follows that not as
much total food can be stored in a small root as a large one.
If the top growth is completely removed carbohydrate manufacture

is stopped, hence any growth initiated must be at the expense of

the reserve food stored in the roots. Providing the top
growth is removed frequently, allowing for little or no food
storage, the reserves soon become depleted and no new growth
can be initiated; the plant cannot manufacture sufficient food
for maintenance and as a result it dies.

When plants are cut in such a manner that a large
proportion of the top growth remains, carbohydrate manufac-
ture may continue. Under complete and frequent defoliation
these plants continue to initiate "recovery" growth after sev-
eral successive defoliations because the root system is large
and contains a large amount of stored food. Eventually the re-
serves of plants treated in this manner will be depleted if close
cutting is continued.

In the case of the 1 inch and 3 inch cultures cut
weekly and biweekly the above points are brought out. After
several complete defoliations the food reserves in the cul-
tures cut to 1 inch were exhausted and death resulted. The
3 inch cultures initiated little new growth and the root system
was severely damaged. Under monthly cutting intervals there was
more food storage and the plants were in a more healthy condiu
tion although they suffered severely from the treatment.

The 9 inch, 12 inch,and check cultures initiated a
good healthy growth after each complete defoliation showing
that much food storage had previously taken place in the roots.
The size and weight of the roots also brings out this point.

VI. CONCLUSIONS

1. Cutting alfalfa frequently and close to the
crown resulted in depletion of the food reserves and a marked
decrease in the yield and vigor of the plants.

2. Alfalfa cut infrequently at a high level (12 inches)
resulted in decreased yields due to the maturity of the plant
and a lack of vegetative growth.

3. Alfalfa remains vigorous when out back to a 6
inch level either biweekly or monthly. At an interval of one
week between cuttings the plants failed to produce sufficient
root system or stored food to maintain the plant over unfavor-
able periods for growth.

4. Cutting back to the 9 inch level gives good re-
sults under the weekly and biweekly intervals of cutting where-
as monthly intervals allow the plants to mature, resulting in a
retardation of vegetative growth.

5. According to this experiment it appears that al-
falfa should be kept pastured back to between the 6 inch to 10
inch level for best results, depending on the interval of graz-
ing. It should be kept in.mind, however, that the results from
greenhouse work is not always applicable to field conditions.
The results will, however, give an indication as to what might
be expected if such an emperiment were carried out under field

conditions.

1.

3.

4.

5.

6.

7.

8.

9.

10.

11.

VII. BIBLIOGRAPHY

Albert, W.B., Studies on the Growth of Alfalfa and
some Perennial Grasses
Jour. Amer. Soc. Agron. 19: 624-654, 1927

Graber, L. P., Penalties of Low Food Reserves in Pastures
Jour. Amer. Soc. Agron. 21: 29-34, 1929

Graber, L. P., Nelson, N. T., Leukel, W. A., and Albert,
W.B., Organic Food Reserves in Relation to the
Growth of Alfalfa and some other Perennial Rer-
bacceous Crops.
Wise. Res. Bul. No. 80, 1927

Granfield, C. 0., The Relation of Organic Food Reserves
to the Effect of Cutting Pasture Weeds at Dif-
ferent Stages of Growth
Jour. Amer. Soc. Agron. 22: 709-713, 1930

Harrison, C.M;, Responses of Kentucky bluegrass to
Variations in Temperature, Light, Cutting, and
FertIIIZIDSe
Plant Physiology 9: 83-106, 1934

Kiesselbach, T. A. and Anderson, A., Alfalfa Investigations
Nebr. Res. Bul. No. 36, 1926

Leukel, W. A., Camp, J. P., and Coleman, J.M., The Effect
of Frequent Cutting and Nitrate Fertilization on
the Growth Behavior and Relative Composition of
Pasture Grasses.

Fla. Tech. Bul. No. 269, 1934

Nelson, N.T. The Effects of Frequent Cutting on the Pro-
duction, Root Reserves, and Behavior of Alfalfa
Journ. Amer. Soc. Agron. 17: 100-113, 1925

Sprague, H. B., The Root Development of Perennial Grasses
and its Relation to Soil Conditions
Soil Sci. 36: 189-209, 1933

Weaver, J. E., The Root Development of Field Crops, 1926
p. 73-75, MOGraw-Hill Book Co., New‘York, N.Y.

Willard, C. J., Root Reserves of Alfalfa with Special Ref-
erence to the Time of Cutting and Yield
Jour. Amer. Soc. Agron. 22: 595-602, 1930

‘ Aoullw

set-«'4‘ ,

“v,

.M'kii'v"-:.w?e*’v‘73mm. . .

Q

g.

3 a
I

"'-“ u..- n

 

   

fi 3: fi.wa~135.a

 

I

8-,

 

WWIGHWINIIHSIIWIW \ IIIVIIEIHIWIWW'IBIWIWEs
3 1293 01085 2416