Experiments with Napier grass

Material Information

Experiments with Napier grass
Series Title:
Bulletin 568 ; University of Florida. Agricultural Experiment Station
Blaser, R. E ( Roy Emil ), 1912-
Ritchey, G. E.
Kirk, W. G.
Arnold, P. T. Dix
Place of Publication:
Gainesville, Fla.
University of Florida Agricultural Experiment Station
Publication Date:
Copyright Date:
Physical Description:
32 p. : ill. ; 23 cm.


Subjects / Keywords:
Grasses -- Field experiments -- Florida ( lcsh )
Dairy cattle -- Feeding and feeds -- Florida ( lcsh )
Beef cattle -- Feeding and feeds -- Florida ( lcsh )
bibliography ( marcgt )
non-fiction ( marcgt )


Includes bibliographical references (p. 31-32).
General Note:
Cover title.
Statement of Responsibility:
Roy E. Blaser ... et al..

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University of Florida
Holding Location:
University of Florida
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All applicable rights reserved by the source institution and holding location.
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18282581 ( oclc )
027107293 ( alephbibnum )


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"-jBulletin 568 September 1955

J. R. BECKENBACH, Director

Experiments with Napier Grass



Fig. 1.-Well fertilized Napier grass gave satisfactory returns under
rotational grazing. Fenced quadrats, as in the middle foreground, were
used in measuring forage yields.

IN TRODUCTION -. -- ... .... - ------ .. ....... ....- ..- .. ......... ...- .. ..... 3
REVIEW OF LITERATURE ......----... ----------...-. ---. .... --- --.-....... 3
ESTABLISHING NAPIER GRASS ..... --........ ....--...--...--- .-----..... ... .........-------.. 4
Adaptation .--------........--.......--..... ... .. ........------------.. ..... ... 4
Strains .---------- ---------........-------.......... ........ ...... -........... .. 4
Propagating and Planting ...-----.. ... ----------.. ....-...----- .. ..- 5
Fertilization .. ................ ......---- ---.. .. ---- 6
Cultivation ..-...------. -..............------------.........------- ..... .. 6
Grazing Management ...... ..-.......-----..--.. ...------------......... .... 7
AGRONOMIC EXPERIMENTS ....-......-- --.......----------- ...----------- -...... 7
Cutting Management ....................... ...... --.......--- ...-------.............. .--- -. 7
Effect of Fertilization on Yields .....-....... ....---- ..------- ..... .-. 10
Quality of Herbage ..--- --.....--------- --......... ............. .. -..... -- ........ 13
Summary of Agronomic Phases .-.. ..--.--..--....... ...--------...---..- .--- .. 15
GRAZING TRIALS WITH BEEF CATTLE .--..-........----......-- --......... -- 15
Grass with High Nitrogen Fertilization --..-...--... -----......-......... .. .... 15
Chemical Composition of Heavily Fertilized Napier Grass ............ 17
Grazing Lightly Fertilized Napier Grass ...............-........................ 20
Summary of Grazing Napier Grass with Beef Cattle .............. .. 22
NAPIER GRASS FOR DAIRY Cows ..--...- ...........- ..- ......-- ..- ... . .. .. 22
Plan of Work with Dairy Cows ..-....... ---------... ----------................ 22
Method of Calculation ................................. ..... ... ...... . 25
Grazing Results ....---------. --- -----.......... ............ ... ... .. .. 25
Five-Year Results and Discussion ......... ... ....... .. ....... 28
Summary of Trials with Dairy Cows .................. ......... .. 30
ACKNOWLEDGMENTS .. -.... .. .... ........................... ......-... .. 31
REFERENCES CITED .. .. ...................................... ..... ............ 31


Investigations with Napier grass (Pennisetum purpureum
Schum.) were conducted at the Florida Agricultural Experiment
Stations for a number of years. The results were not brought
together promptly at the conclusion because of changes and re-
organization of the staff.
Since that time, new grass introductions and changing fer-
tilizer practices have combined to limit the general usefulness of
Napier grass. However, under tropical and sub-tropical condi-
tions when a perennial grass for year-round forage is desired,
this grass still has a place. It is hoped that the information con-
tained here will be of value under such conditions.

Experiments with Napier Grass

and P. T. Dix ARNOLD4

It is generally known that quality, reproduction and produc-
tivity in livestock are associated with the nutrients in feeds they
consume as well as with breeding and management. Some native
herbage in Florida is low in nutritive value, but noted improve-
ments are being made in feed supply by introducing and develop-
ing improved forage plants, along with good cultural and man-
agement practices.
Napier grass was grown in Florida long prior to 1937, but its
value as a grazing crop had not been determined previously.
The practice of continual grazing of Napier grass resulted in low
yields and ultimate destruction of the stand. Consequently, it
was not considered practical for pasture. It has been demon-
strated that a stand of Napier grass can be maintained for sev-
eral years by adequate fertilizer applications and rotational graz-
ing, as shown in Figure 1. Grazing trials were started in 1937
to measure the value of Napier grass pasture for fattening
cattle, and in 1938 to determine its importance as a grazing crop
for dairy cows.
Napier grass, Pennisetum purpureum Schum., was first intro-
duced into the United States from Africa in 1913 (14)5. It is
a large tropical cane-like perennial which grows 7 to 15 feet in
height. There are many strain differences.
Napier grass was first distributed to Florida farmers in 1915
(14), but is not grown extensively. Two factors which limited
its use and propagation have been improper management and
a fungus disease, eyespott" (Helminthosporium ocellum Faris).
Eyespot was first reported by Leukel and Camp (8) in 1935.
This disease was of such virulence that it destroyed whole
stands in some localities. Eyespot-resistant improved strains
I Now Professor of Agronomy, Virginia Polytechnic Institute, Blacks-
burg, Virginia.
2 Formerly Agronomist, Division of Forage Crops and Diseases.
B.P.L.S.A.E., USDA, Gainesville; more recently Agronomist in Charge.
Suwannee Valley Agricultural Experiment Station, Live Oak, Florida.
Now Vice-Director in Charge, Range Cattle Experiment Station, Ona,
'Associate Dairy Husbandman, Florida Agricultural Experiment Station.
'Italic figures in parentheses refer to literature cited.

4 Florida Agricultural Experiment Stations

of Napier grass were developed subsequently by Ritchey and
Stokes (12) and by Burton (1).
This grass has been used primarily for soiling (cutting and
feeding green) in tropical locations (3, 4, 11 and 16). In Flor-
ida, tests have been made to study its value for silage (10, 13).
The silage was found to be inferior to that of sorghum, corn or
sugar cane when only two cuttings were made during the grow-
ing season.
There are few experimental data on the grazing value of
Napier grass. Wilkie and Takahashi (16) report that one
Hawaiian plantation has used Napier grass successfully when
grazing was delayed until the grass reached a height of six feet
and with opportunity for regrowth after the herbage was con-
An endeavor has been made by the Florida Agricultural Ex-
periment Station to use this grass for hay, but it was not pos-
sible to preserve it properly because of difficulty in curing the
coarse stems.
From later work, it is evident that combinations of some
legumes with sod-forming grasses properly fertilized and man-
aged may extend the grazing season and also return more total
digestible nutrients per acre than Napier grass provided.

Napier grass is adapted widely and the roots and crowns
tolerate all temperature extremes in Florida. The tops are
killed readily by frosts. New growth from the crowns is not
ready for grazing until late spring. In north central Florida
it generally furnishes herbage for grazing from May to No-
vember. The grass furnishes grazing for a short season, and
a high yield of quality herbage can be obtained only under care-
ful grazing management.
This grass is adapted to reasonably well-drained fertile soil.
It is productive on fertilized sandy soils, but grows profusely on
the Everglades peat soils where it has reached the status of a
weed on vegetable farms. It produces a high yield of herbage
on drouthy sand soils.
There are many strains of Napier grass which differ in dis-
ease resistance, yield, leafiness and other characteristics. This

Experiments with Napier Grass 5

grass produces seed readily in South Florida. Space planting
tests show much variability among seedling plants. Any de-
sirable characteristics or phenotypes which occur in seedling
plants need not be fixed, since this grass usually is propagated
by foot and stem cuttings.
In the breeding program the primary objectives have been
to produce high-yielding leafy strains that are eyespot-resistant.
Several strains which proved to be greatly superior to mass
selected types were tested in an experiment under different
management and fertilizer practices during the period 1942 to
1944. Selected strains of Napier grass varied in height and
leafiness, as shown in Figure 2. The average green yields
of three varieties for all fertilizer treatments show that No. 4
was the most productive strain (Table 1). Because of its leafi-
ness and productivity, this strain is recommended over others
and has been distributed to farmers.


Strain Fresh Green Forage per Acre
S 1942 1943 1 1944 1 Average
pounds pounds pounds pounds
4 ...........-..... 14,883 10,729 18,446 14,686
160 ................. 11,979 8,281 13,824 11. f1
167 .................. 11,689 7,694 14,581 11,321

Least Significant Difference:
P- .05 .......... 1,542 1,315 2,099
P- .01 ........... 2,033 1,738 2,773 ....

The percentage of leaves of the three strains did not differ significantly.

Although Napier grass produces seed in South Florida, gen-
erally it is propagated readily by planting rootstalks (rhizomes)
or stem cuttings. Seedling plants are difficult to grow and they
usually produce undesirable plant types.
Stem and root cuttings are planted one to two feet apart in
rows spaced five to eight feet. Root cuttings are covered com-
pletely with two to five inches of soil. Three-joint stem cut-
tings are stuck into the soil at about a 45 angle at a depth to
leave the uppermost node exposed.

6 Florida Agricultural Experiment Stations

The planting date is important. Root pieces may be planted
during February and March, while stem cuttings or rootstalks
may be used during June or July. Stem cuttings have been
used successfully for early spring planting by cutting the stems
in late fall before frost and burying them deeply enough in
damp soil to avoid drying or freezing. Early spring plantings
are preferred, because of less weed competition and higher
yields. Although no tests have been made to study seedbed
preparation, it is known that a thoroughly prepared seedbed
gives best results.
It is necessary to apply fertilizer liberally as few, if any,
soils in Florida possess a sufficiently high reserve of fertility
to support good growth of Napier grass. Complete fertilizers,
5-7-5, 6-6-66 or similar formulas, applied at rates of 400 to 600
pounds per acre in the row before planting, have been found to
stimulate growth and shorten the period of establishment. Best
growth response was obtained from nitrogen fertilizers. Growth
was improved on the more acid soils when lime was applied in
addition to the complete fertilizers.

Napier grass does not shade the ground or spread much dur-
ing the first year. Therefore it is necessary to cultivate at least
twice during the first season to control weeds and to augment
release of nitrogen from decaying plant material. After the
first year the necessity of cultivation will depend on weediness
These numbers indicate amounts of nitrogen, phosphoric acid and
potash, respectively, in the fertilizer formulas.

Fig. 2.-Three strains of Napier grass (Nos. 4, 160 and 167) were selected
to investigate for forage purposes, based on growth and leafiness.

Experiments with Napier Grass 7

of the land and growth of the grass. One disking annually in
early spring with a heavy disk harrow gave excellent results
with pastures grazed by beef and dairy cattle.

Napier grass is a tall, erect plant. When grazed heavily and
continuously, the animals remove the leaves. With rather com-
plete leaf removal, organic nutrient reserves (starches, sugars
and other compounds) in the roots and underground stems
become depleted and new growth is produced slowly or the
plants die. The stand of Napier grass can be maintained well,
provided there is a short grazing period (5 to 10 days) followed
by a long re-growth period (20 to 30 days). To maintain this
grass, it must be grazed rotationally and fertilized.

The following experiment illustrates the relationship between
yield and management. Seven management treatments were
compared, as shown in Table 2. Each yield is given as an
average for 24 plots (three strains with each of eight fertilizers).
The grasses were not cut for yield determination during 1941,
to promote establishment of satisfactory stands and store a good
supply of organic nutrient reserves in rootstalks. The total
herbage yields in green weights are given for 1942 and 1943 for
all management treatments. In 1944 all plots were cut two times
to measure residual effects of the various management treat-
ments on yields.
The total grass yields when stripped to simulate grazing at
three feet and five feet were 9,258 pounds and 8,103 pounds per
acre, as shown by the average yields for 1942 and 1943. When
the grass was cut back to five inches tall whenever a height of
three or five feet was reached the yields were 12,065 and 12,847
pounds, respectively. The average green yield was 16,605 pounds
per acre for the plots that were cut twice per season. These
are shown in Table 2.
Quality of herbage is more important than total yield. Herb-
age quality depends upon leafiness. Leafiness was associated
with management treatment, as shown by an average of 88 to
93 percent of leaves for plants stripped to simulate grazing and
50 to 53 percent of leaves when cut at heights of three to five



Propor- i Total For-
Management Treatments on Separate Plots ............. YearI tion of Average Yield age Yields
_1942 1943 Leaves Forage Leaves 1944"* "
pounds pounds percent pounds pounds pounds .
Leaves stripped when grass 3 ft. high .................... 10,309 8,206 93 9,258 8,610 19,983
Leaves stripped when grass 5 ft. high ---.........--... 9,365 6,841 88 8,103 7,131 19,704
Cut to 5 inches when 3 ft. high .................-.................. 13,213 10,917 50 12,065 6,032 10,839
Cut to 5 inches when 5 ft. high ...............-----............- 14,883 10,810 53 12,847 6,809 11,755
Cut to 20 inches when 3 ft. high .............................. 11,326 9,676 67 10,501 7,036 17,548
Cut to 20 inches when 5 ft. high ..-....--.. --.... ............ 12,269 10,160 57 11,215 6,393 17,345
Cut two time during year .-----------..-................ 18,580 14,623 43 16,605 7,140 12,182

Least Significant Difference P .05.......... ... ........ 2,323 2,291 ........ ....... 3,146 2
P .01......................... 3,122 3,028 .......... 4,174

*Each yield was computed as the average from 24 plots (8 fertilizers with 3 strains).
"** D'uring 1944 all plots were harvested two times to measure residual effects of the management treatments.

Experiments with Napier Grass 9

feet. An average of only 43 percent of leaves was obtained when
cut twice annually. Cutting this grass at infrequent intervals
resulted in the production of high yields of very coarse, stemmy
herbage. Stripping grass to simulate grazing reduced yields,
but the herbage was very leafy. Total leaf production among
these management treatments was similar.


Fig. 3.-The stand of Napier grass was maintained well throughout six
years of rotational grazing. This picture shows the stand in the seventh

Yields taken during 1944 to measure residual effects from
1942 and 1943 cutting treatments show that grass plots stripped
to simulate grazing or cut to 20 inches from the ground pro-
duced higher yields than grass that was cut back to the ground
twice annually or cut after a height of three to five feet was
reached. This indicates that Napier grass is maintained in a
productive condition when the stems are not cut back completely
or defoliated periodically as in grazing. High yields may be
associated with high carbohydrate reserves and possibly lateral
spreading under grazing management conditions. It has been

10 Florida Agricultural Experiment Stations

observed that new leaves develop rapidly from axial buds at
the nodes along the defoliated stems.
The longevity of Napier grass under rotational grazing has
been demonstrated in grazing experiments conducted with dairy
cows. In these trials five lots of Napier grass were grazed ro-
tationally. Grazing was initiated when the grass was three to
five feet in height. The number of cows was adjusted so that
about 90 percent of the leafage was consumed in five to seven
days, after which the cows were moved to another lot, in suc-
cession. This allowed 20 to 28 days for recovery after each
grazing period. Light grazing was practiced during the late
season to prevent excessive reduction of leaf area, and thus
allow a build-up in root reserves. Under this grazing practice
an excellent stand of grass was maintained and the density
of stands increased. The stand of grass after seven years of
grazing is shown in Figure 3.

Tests designed to study fertilizer rates and ratios, time of
application, and source of nitrogen on growth of Napier grass
have been made on an Arredondo fine sand soil, as shown in
Tables 3, 4 and 5. The average yield during 1941-1944 was
1,695 pounds of dry matter without fertilizer, as compared with
3,081 pounds when 32 pounds of nitrogen, 64 pounds of phos-
phoric acid (P205) and 32 pounds of potash (KO0) were applied
annually. Double and four times the nitrogen applications in-
creased the yields to 4,226 and 8,868 pounds of dry matter per
acre, respectively.
Because Napier grass is known to give significant yield in-
creases from nitrogen fertilization, tests were carried on to
measure growth responses from single annual applications com-
pared with several split applications. A total of 64 pounds of
nitrogen was applied in March in one application in one series
of plots, and split into two applications of 32 pounds each in
March and June in another series of plots (Table 3). In two of
the four years yields were significantly higher from the split
application. The four-year average yield was higher from split
nitrogen applications. An average of 4,226 pounds of herbage
was obtained when 64 pounds of nitrogen per acre were applied
in March, as compared with 6,079 pounds of herbage per acre
when 32 pounds of nitrogen were applied in March and June.
In another series of plots nitrogen was applied in March at the


Total Fertilizer Applied* Time of __Dry Matter per Acre _
Phosphoric Nitrogen
Nitrogen Acid_ Potash Application** 1941 1942 1943 1944 Average
pounds pounds pounds [ pounds Ipounds pounds pounds pounds .

0 0 0 None ........ 1,458 1,483 2,145 1,695
32 64 32 March 3,217 2,400 2,938 3,769 3,081
64 64 32 March 4,119 3,496 5,127 4,162 4,226
128 64 32 March 8,422 8,800 10,875 7,375 8,868
64 64 32 32 pounds in
March, June 6,381 6,600 5,241 6,164 6,079
128 64 32 32 pounds in
March, June, 6,199 5,943 6,610 5,814 6,142
July, August** __

Least Significant Difference: ....................... .05 2,630 1,621 2,016 1,073 ..-
P-.01 3,509 2,183 2,715 1,446

Thirty-two pounds of nitrogen is equivalent to 200 pounds of nitrate of soda, which was the form used in the test.
Thirty-two pounds of phosphoric acid (P-Os) is equivalent to 200 pounds of superphosphate.
Thirty-two pounds of potash (K2O) is equivalent to 64 pounds of 50 percent muriate of potash.
**The phosphate and potash were applied in March each year, when the nitrogen was used in split applications as indicated.


12 Florida Agricultural Experiment Stations

rate of 128 pounds per acre and in four applications of 32 pounds
of nitrogen each in March, June, July and August (Table 3).
The yields were consistently higher for the plots which received
all the nitrogen in one application. Average yields for the four-
year period were 8,868 pounds per acre when 128 pounds of
nitrogen were applied in March, as compared with 6,142 pounds
when the nitrogen was applied in four applications of 32 pounds
each. With split nitrogen applications, that applied during July
and August apparently was not utilized efficiently.
Yield tests carried on with nitrogen fertilizers from different
sources (nitrate of soda, sulfate of ammonia, urea and calcium
cyanamid) gave variable responses during the individual years
of testing. The differences in average yields for the four years
were not significant (Table 4). These variable yield responses
are attributed to differences in stand and weather conditions.


Source of Nitrogen _Dry Matter per Acre
S1941 1942 1943 1944 Average
pounds pounds pounds pounds pounds
Nitrate of soda ............ 3,217 2,400 2,938 6,164 3,680
Sulfate of ammonia .... 3,767 4,254 3.649 5,292 4,241
Uramon ..........-- ............ 4,634 3,849 3,903 6,605 4,748
Calcium cyanamid ...... 5,676 2,738 3,324 5,150 4,219

Least Significant
P- .05 .........-- .. 2,630 1,621 2,016 1,073 ...
P- .01 ................ 3,509 2,183 2,715 1,446

All plots received 64 pounds of phosphoric acid (POs) and 32 pounds of potash
(KO2) annually, except in 1944 when one-half the rate of phosphoric acid was used.
Thirty-two pounds of nitrogen was applied annually in March, except in 1944 when
an additional 32 pounds was applied in June.

In the Napier grass grazing test for dairy cows, a complete
fertilizer supplying 30 pounds of nitrogen per acre was applied
in March and additional nitrogen sidedressings at the rate of
30 pounds per acre were made during the growing season
(Table 5). The sidedressing was applied in one application in
May with two of the grazing lots and in four applications of
7.5 pounds each in May, June, July and August in the remaining
three lots.

Experiments with Napier Grass 13

Yields of herbage were somewhat higher for the plots which
received all the nitrogen in early season. These data also sug-
gest poor nitrogen utilization from late applications. This
would be expected, since Napier grass reaches its peak in pro-
duction during June to August.


Year Lots 1 and 3 Lot 5* I Lots 2 and 4
pounds !pounds pounds
400 pounds of 5-7-5 complete fertilizer in Spring;
and 7.5 pounds of nitrogen after first four grazings.

1939 .....................-- .....--..... 3,850 2,825 3,367
1940 ...............----- -...--..- .... .... : 2,656 2,193 2,636

500 pounds of 6-6-6 complete fertilizer in Spring:

30 pounds of
7.5 pounds of nitrogen after Nitrogen in
first four grazings. May
1941"* ............ ....-....................... 1,751 1,457 1,952
1942 .....----- -----------.............................. .. 2,124 1,848 2,317
1943 ...............-............. .-- .... 2,021 1,995 2,375
1944 ...--..-........ ....------------ .... --2,315 ........ 2,415

Average 1941-1944 .................. 2,053 ........ 2,265

Lot 5 was not considered in these yield comparisons because of a soil variability.
** Late frost and a dry Spring delayed the initial grazing.

Grazing management or cutting stage, through its effect on
stemminess or herbage, definitely affects herbage quality. Plant
height, dry matter content, leafiness and protein content of
stems, leaves and ungrazed residue of samples taken from the
fields used for beef cattle grazing tests during 1938 are shown
in Table 6. The dry matter content of Napier grass leaves,
sampled before grazing, ranged from 13.7 to 22.6 percent. The
proportion of leaves varied from 25 to 45 percent under actual
grazing (Table 6). The stemminess tended to increase slightly
as the season advanced. The crude protein content of the leaf
blades at the time grazing started varied from 9.2 to 14.4 per-
cent, as compared with 3.9 to 6.5 percent in the stems. The un-


S Napier Grass Before Grazing Ungrazed Residues
Grazing Lots Dates*
Tour Plant Dry Leaves Crude Protein Stem Dry Crude
Height Matter i Leaves Stems Height Matter Protein
Inches percent percent percent percent inches percent percent

1 1, 2 May 10, 16 38 16.9 45 10.4 5.1 16 14.5 5.0 t
3, 4 May 21, 27 38 19.1 33 9.2 5.0 14 17.5 5.3
II 1, 2 June, 13, 24 42 10.2 35 11.8 6.2 19. 10.4 8.5
3, 4 July 1, 9 51 13.2 33 11.7 5.0 20 13.8 7.3
III 1 July 20 52 18.4 30 11.4 4.5 19 16.0 5.3
2 July 26 48 13.7 30 11.7 5.2 17 12.5 5.3
3 August 1 54 14.8 30 10.8 3.9 19 16.0 4.7
4 August 8 47 17.8 34 10.0 4.1 20 16.6 4.7
IV 2, 2 August 15, 22 40 17.2 35 11.6 4.0 19 15.3 4.6
3, 4 Aug. 29, Sept. 3 42 19.9 28 10.6 4.9 23 19.8 5.6
V 1, 2 Sept. 14, 21 37 16.2 33 12.2 5.4 20 19.8 4.2
3, 4 Sept. 27, Oct. 4 36 17.6 25 14.4 6.2 19 18.9 5.8
VI 1, 2 Oct. 15, 18 34 22.6 34 11.6 4.8 22 23.1 5.4
3, 4 Oct. 25, 26 28 22.6 30 13.2 6.5 20 23.2 6.2

Average ...............-................... 41.9 11.5 5.0 19.1 5.6

Napier Grass Cut Twice As For Silage

1, 2 August 7 86 I30.2 23 9.5 2.7 .-
3, 4 August 5 87 26.1 25 8.4 2.4
1, 2 October 25 76 24.6 30 12.3 3.5
3, 4 October 25 74 28.4 30 13.7 3.6 .

Grass samples were taken on the days when the grass had been grazed down, and cattle were rotated to the next lot.

Experiments with Napier Grass 15

grazed residue composed largely of stems, ranged from 4.2 to
7.3 percent of crude protein.
When the grass was cut twice annually, as is conventional for
silage, the forage was very stemmy, with only 23 to 30 percent
of leaves. The crude protein in stems varied from 2.4 to 3.6
percent and in the leaves from 8.0 to 13.7 percent. The man-
agement test discussed earlier showed that frequent cutting
resulted in increased leafiness. However, a higher proportion of
leaves was obtained under grazing conditions than from cutting

Eyespot-resistant strains of Napier grass were developed from
selected seedling plants.
Better stands were established from spring planting than from
late plantings.
When cut twice yearly, high yields of grass were obtained
that were stemmy. Yields of leafy herbage were similar for
seven stripping and cutting treatments. The stripped leaves
were higher in crude protein and lower in fiber than the stem
portion of Napier grass.
Higher rates of nitrogen applications resulted in increased
yields of forage under uniform cutting treatments. Four sources
of nitrogen produced similar amounts of forage. Less Napier
grass was produced after applying 64 pounds of nitrogen in
March than from applications of 32 pounds of nitrogen in March
and again in June.

A 15-acre area on Leon, Plummer and Arredondo sand was
cleared, plowed, fertilized and planted to Napier grass in March
1937. Rhizomes of mass selected eyespot-resistant strains of
Napier grass were planted in seven-foot rows which received
400 pounds of a 5-7-5 fertilizer at time of planting. Thereafter
complete fertilizer was applied annually and two to five applica-
tions of nitrogen at the rate of 12 to 16 pounds per acre were
made as sidedressings.
In 1937 the area was cultivated twice to control weeds. In
following years the grass was disked with a double disk harrow
while dormant in February or March and cultivated once be-

16 Florida Agricultural Experiment Stations

tween the rows in 1938 and 1939. The growth and stand of
grass was retarded in some fields by variation in soil fertility
and excessive moisture during certain times of the year.
In June 1937 the grass was harvested for silage, after which
the area was fenced into five lots of three acres each to practice
rotational grazing. Grazing was begun when the grass reached
a height of three to four feet. The number of yearling steers
was adjusted so that they would consume most of the blades
in five to eight days. The steers were weighed individually each
time they moved to a different lot. Water and mineral supple-
ments were available at all times.
Four movable cages 10 feet square were placed in each lot.
These prevented the grass from being grazed and made it pos-
sible to obtain samples for yield measurements and chemical
analysis. Grass samples, hand stripped to simulate grazing,
were obtained immediately after the animals were moved to
the next lot.
Best results were obtained in 1938 when steers made an aver-
age daily gain of 1.73 pounds and produced 430 pounds per
acre (see Fig. 4). The lowest were in 1940 when the cattle
gains averaged 290 pounds per acre. The low production in 1940
was caused largely by a smaller total application of nitrate of
soda and lack of cultivation with subsequent weed competition.
Improper drainage caused partial flooding of some fields in 1940,

Fig. 4.-These steers made satisfactory gains in weight and condition
on Napier grass grazed rotationally.



Experiments with Napier Grass 17

and cold injury to rhizomes reduced number of shoots, both of
which reduced the yield of grass.
The average grazing days and gains from five lots totaling 15
acres of heavily fertilized Napier grass grazed rotationally
during the 1938, 1939 and 1940 seasons, are given in Table 7.
An acre of Napier grass provided 235 steer-days of grazing in a
season, and cattle made 369 pounds of gain, which gave an aver-
age daily gain of 1.57 pounds.


Heavily Fertilized Grass* Lightly Fertilized Grass**
Grazing Average Average Grazing Average Average
Year Days Gain Daily Days Gain Daily
per Acre per Acre Gain per Acre per Acre Gain
pounds pounds pounds pounds
1938 ........-.... 248 430 1.73 |
1939 ..-..-...-... 227 386 1.70 170 263 1.55
1940 .............. 229 290 1.27 152 193 1.27

Average .... 235 369 1.57 161 228 1.42

Applied annually in March,-400 pounds of 5-7-5 fertilizer. Additional nitrate of soda
applied,-300 pounds in 1938, 375 pounds in 1939 and 210 pounds in 1940.
** Applied annually in March,-400 pounds 5-7-5 fertilizer.

The stand of grass was not as dense in 1940 as in 1938. The
retardation in stand was affected by differences in palatability,
which resulted in some plants being oversized. Since planting
material was taken from mass selections of eyespot-resistant
Napier grass, there were numerous plant variations in such char-
acteristics as leafiness, pubescence, height and thickness of stems,
and productivity. Observations showed that test animals had
quite definite grazing preferences, resulting in overgrazing and
reduction in root reserves and growth with many plants (Figure
5). This indicates the desirability of using plants of uniform
strains when conducting grazing tests with tall growing plants.

In 1938 and 1939 samples from the heavily fertilized Napier
grass were taken at regular intervals for chemical analysis.
Movable cages 10 feet square protected the Napier grass for



On a Dry Basis
Year Dry Crude Crude N-Free Crude C I
Matter Protein Fiber Extract Fat Ash Ca. P.
Percent Percent j Percent I Percent j Percent Percent Percent TPercent "

Napier Grass Blades Grazed by Steers

1938 ......... 18.9 12.1 32.4 46.2 2.8 6.5 0.47 0.33

1939 ... 20.6 12.5 32.6 45.4 2.9 6.6 0.48 0.33

Average ...... 19.8 12.3 32.5 45.8 2.9 6.6 0.48 0.33

Ungrazed Residue, Primarily Stems and Sheaths

1939 .............. 13.8 5.5 32.2 48.8 1.6 5.9 0.25 0.29
i ~~~~~ ~. I.2 _.2 _ _ 1 _

Experiments with Napier Grass 19

sampling. Samples of grass were taken at the time the steers
were moved to the next lot, after which each cage was placed
in a different part of the field. In Table 8 the average chemical
composition of Napier grass grazed by the steers in 1938 and
1939 and of the ungrazed residue collected in 1939 are given.
The Napier grass eaten by the steers, primarily leaf blades,
averaged 12.3 percent crude protein on a moisture-free basis,
while the ungrazed residue (mostly stems and sheaths) contained
5.5 percent crude protein. The ungrazed residue was lower in
dry matter, fat and ash and higher in fiber than that consumed
by the steers.
Kidder (6) showed that Napier grass leaves on a moisture-
free basis contained 8.4 percent of digestible protein and 65.4
percent total digestible nutrients. It was estimated that in
1938 steers grazing heavily fertilized Napier grass consumed
about 107 pounds of green forage daily.
Since Napier grass grown in 1938 contained an average of
18.9 percent dry matter (Table 8), the steers consumed about
20.2 pounds dry matter daily which contained 1.7 pounds of
digestible crude protein and 13.2 pounds total digestible nutrients.
The average daily gain per steer in 1938 was 1.73 pounds. Thus
the steers consumed 0..98 pounds digestible protein and 7.6 pounds
total digestible nutrients per pound of gain. Shealy and asso-
ciates (13) showed in three trials that steers fattened in dry
lot on a ration of cottonseed meal, ground snapped corn and

Fig. 5.-Cows grazed the Napier grass plant at the left but had not touched
the tall plant at the right.

*.~iiL>Pc *; 7 I



20 Florida Agricultural Experiment Stations

Napier grass silage consumed an average of 1.1 pounds diges-
tible protein and 6.3 pounds total digestible nutrients per pound
of gain.

In 1938 an additional 71/-acre area largely on Arredondo sand
was planted to Napier grass to measure its grazing value when
fertilized at a light rate. During the planting year complete
fertilizer and nitrate of soda were used to insure a good stand of
strong plants. Because of the favorable season and fertilizer
used, this area was ready for grazing by June 29. The area was
divided into five lots of 11/2 acres each to permit rotational
During 1938 in a 117-day grazing period, two-year-old steers
were fed an average of 2.27 pounds of 41 percent cottonseed
meal daily to study the effect of supplemental feed on gains.
The number of steers ranged from 10 to 15, according to the
amount of forage available. The steers made an average daily
gain of 1.72 pounds and 329 pounds gain per acre. Each acre
of Napier grass plus the cottonseed meal provided feed for 191
steer-days. Average daily gain is similar to that made by steers
on heavily fertilized grass, Table 8, and the total gain per acre
is 101 pounds lower for a 131-day shorter period. Results of
this preliminary trial showed that supplemental feeding in-
creased carrying capacity of the pasture.
In 1939 and 1940 an application of 5-7-5 fertilizer at the rate
of 400 pounds per acre was made annually in the spring without
additional sidedressing of nitrogen during the grazing season.
Yearling steers were used as grazing animals in 1939 and yearling
heifers in 1940.
Two-year results show that yearling cattle made an average
daily gain of 1.42 pounds and that 155 animal-days of grazing
were furnished per acre, resulting in a total of 219 pounds gain
in body weight. There was a gradual decrease in amount of
feed available as the grazing season progressed. During the
first two rotations from 8 to 10 animals were required to con-
sume the grass on 7.5 acres, while in the fifth rotation from
three to five animals were sufficient.
A comparison of the animal gains per acre on the heavily
and lightly fertilized Napier grass shows that the amount of
grass is dependent largely upon the amount of fertilizer applied,

Experiments with Napier Grass 21

as presented in Table 7. Figure 6 shows that the rate of stock-
ing on the heavily fertilized grass was one animal per acre in
May and September, while from June 1 to August 31, the height
of the growing season, two acres supported more than three ani-
In these two trials Napier grass furnished good grazing from
May until mid-October, or 165 to 176 days annually. Individual
weights obtained each time the animals progressed in the rotation
showed average daily gains in excess of 1 pound per animal during
the entire grazing season. The grass was palatable and nutri-
tious to the cattle under the rotational system of grazing.




Grazing Season

Fig. 6.-Changes in grazing capacity (steers per acre) of heavily fertilized
Napier grass during the 1938, 1939 and 1940 seasons.

Considerable grazing was available from both heavily and
lightly fertilized Napier grass after the experimental animals
were removed in mid-October, but the forage was stemmy and
coarse. The Napier was left ungrazed until late November
to build up a reserve of nutrients in the roots. The forage which
accumulated from October 15 to late November was grazed later
by the breeding herd. Mature cows maintained their body
weight for several weeks on the accumulated growth of Napier

22 Florida Agricultural Experiment Stations

Results of the grazing trials show that application of nitrate
of soda during the grazing season increased grazing capacity
from 161 to 235 cattle-days per acre and the gains from 228
to 369 pounds. The average daily gain was 1.42 pounds on the
lightly fertilized grass, compared to 1.57 pounds on the heavily
fertilized grass. Returns obtained from these two methods
of fertilizing Napier grass will depend upon cost of the fertilizer
and the improvement in grade of the cattle making the highest
An area of 8 acres, divided into 5 lots, was planted to mixed
strains of Napier grass in March 1938 for evaluation of this
crop with dairy cattle. The method of establishment was the
same as for the beef cattle phase. After the first year the
area was disked once each spring. This controlled weeds satis-
factorily and seemed to stimulate early growth.
During 1938 through 1940 an application of 5-7-5 fertilizer at
the rate of 400 pounds per acre was made in March. Four appli-
cations of nitrate of soda were made at the rate of 12 pounds
of nitrogen per acre. Beginning with 1941 the fertilizer prac-
tices were changed so as to compare early-season nitrogen ap-
plication with several split applications. A 6-6-6 complete ferti-
lizer was applied at the rate of 500 pounds in March and an
additional 30 pounds of nitrogen was applied in May on two
lots. The remaining three lots (1, 3 and 5) each received 7.5
pounds of nitrogen applied after each of the first four grazing
tours. Yields for these treatments are given in Table 5.
When grazing was delayed until the grass in lots reached three
to four feet in height, the lots grazed during the last part of a ro-
tation became tall and coarse. To avoid this, grazing was
initiated somewhat early and the cows were moved from lot to
lot, allowing about three or four days in each during the first
grazing tour.
Three movable cages were placed in each lot to obtain quadrat
yields of grass and samples for analysis. The grass in the caged
quadrats was stripped by hand twice while each lot was being
grazed. The stripped leaves were to simulate the amounts
The area was divided into five 1.6-acre lots to provide for
rotational grazing-the plan being to graze each lot approxi-

Experiments with Napier Grass 23

mately one week and allow four weeks for the grass to grow
before being grazed again. The time interval for rotation was
estimated by observation of the growth of the plant and by be-
havior under grazing with beef cattle in the preceding year.
Gates were placed from each lot to a lane where water, mineral
supplement and shade were accessible for the cows at all times.
Only one gate was opened at a time into the lot currently being
It has been pointed out in the agronomic phase of this study
that Napier grass has an upright growth habit. Re-growth
following grazing comes from axial buds along the ungrazed
stems or canes. Too close grazing reduces the stems and the
number of buds, so that leaf production is impaired. On the
other hand, insufficient grazing allows the stems to grow tall
(8 to 16 feet) and produce little axial growth or desirable leafy
material within reach of the cows.
Grazing was begun in the spring in the Gainesville area7
when the grass was three to four feet tall, and the number of
grazing animals was adjusted so as to leave the grazed stems
at three to four feet in height when the cows were moved to the
next lot. This practice appeared to allow plenty of buds for re-
growth and yet not let the stems grow too tall (see Fig. 7).
Early in the grazing season when herbage was limited from
8 to 10 cows were used. Later, during the period of more lux-
uriant growth, six to eight more cows were added to utilize
S The top growth of Napier grass is killed to the ground when the
temperature goes lower than freezing.

Fig. 7.-Napier grass before and after a grazing tour by dairy cows.

Ai g

r ;0
IBrn ^l^^^

24 Florida Agricultural Experiment Stations

the forage produced. Still later in the season, the number of
animals was reduced to adjust for the declining growth rate of
the grass in autumn. Late in autumn all cows were removed
in an attempt to permit sufficient regrowth to generate adequate
nutrient root reserves for over-wintering and to stimulate rapid
early spring growth the following year.
Jersey cows from the Experiment Station dairy herd were
used throughout the study. Animals selected for this work
were past the peak of production in the current lactation and
were mature in most instances. Younger cows had to be in-
cluded at times when too few mature animals were available at
the proper stage of lactation. It was necessary to use even dry
cows occasionally in 1943 to utilize fully the growth of herbage.
The cows were weighed on three consecutive days at the be-
ginning and end of each trial and once weekly during the grazing
season. All cows were milked twice daily in the barn and com-
plete milk production records were kept. Individual composite
samples of one day's milk were obtained near the middle of each
month for butterfat determinations. The cows were on pasture
continuously except for about an hour at each milking time.
A concentrate mixture was fed in the barn at milking time at
the rate of about 1 pound of concentrates to 3 pounds of milk
produced-the offering being adjusted at weekly intervals, when
necessary, to the decline in production due to advancing lacta-
tion. Concentrates were fed in even pounds for convenience of
attendants at the barn. The concentrates were a mixture of corn
feed meal, wheat bran, dried brewers grains, dried citrus pulp
and cottonseed meal. It was calculated to contain 17 percent of
total crude protein, 13.5 percent of digestible protein and 75.0
percent of total digestible nutrients based upon average com-
positions as given by Morrison (9). Due to wartime changes in
availability of feed, several substitutions of ingredients were
necessary in the 1942 and 1943 seasons so that the concentrate
mixture was calculated to contain 16 percent of total crude
protein and 70.8 percent of total digestible nutrients during
those seasons.
The investigation began with a preliminary year while the
stand of Napier grass was becoming established. Evalution of
the grazing value in terms of cow-maintenance and milk pro-
duced per acre of crop was continued over the following five-
year period. This duration took into account possibility of
seasonal differences (rainfall and temperature) and age of the

Experiments with Napier Grass 25

plants. Also a larger number of records tended to offset varia-
tions expected between individual cows.

The inverse calculation method was used to estimate the
amount of total digestible nutrients which the cows obtained
from Napier grass. For this purpose the nutrient requirements
of each cow were computed by applying the Morrison standard
with regard to body weight, milk yield and butterfat percen-
tage. The running average weight of each cow obtained from
the weekly weighing was used to calculate the maintenance
requirements for total digestible nutrients during the week. Re-
quirements for milk production were calculated weekly from
the amount of milk produced, using the butterfat test for the
current month. The difference between the calculated nutrient
requirement and the nutrients supplied by supplementary con-
centrates fed during milking time were presumed to have been
obtained from the pasture.
When it was necessary to use dry cows to help utilize the
forage, the requirements for maintenance, together with the
factors for changes in weights, were calculated according to the
method of Knott, Hodgson and Ellington (7). These are the
methods of computation recommended in the "Preliminary Re-
port on Pasture Investigation Technique" by a joint committee
of American Society of Agronomy, American Dairy Science As-
sociation and American Society of Animal Production (5).

Preliminary Season-1938.-Crowns of Napier grass of mixed
unselected strains were planted in March. By June, sufficient
growth had been attained to begin grazing. Since little was
known about the behavior of Napier grass under grazing, and
since the first-year stand was expected to produce somewhat less
herbage while becoming established, it was felt that this season
should be regarded as preliminary. However, complete records
were kept so as to analyze the plan and to make any adjustments
deemed advisable before starting the planned five-year trial.
Ten cows started the trial and later four more were added. A
total of 1,218 cow-days of grazing was obtained during 107
calendar days on eight acres during the preliminary season.
It was calculated that 1,168 pounds of total digestible nutrients
per acre were obtained and that 53.6 percent of the nutrients

2d Florida Agricultural Experiment Stations

required for maintenance and milk production were provided by
Napier grass.
It was estimated that a cow consumed 70 or more pounds of
Napier grass daily per 1,000 pounds live weight. This amount
provided neither sufficient protein nor enough total digestible
nutrients to maintain body weight and optimum milk produc-
tion. Two cows (343 UF and 401 UF) on Napier grass alone dur-
ing the preliminary season dropped in both milk production and
body weight until about 16 to 18 pounds of milk were being pro-
duced daily. Thereafter, body weight no longer declined, al-
though milk production continued to decrease. When these two
cows were returned to the regular herd, where they received
supplemental concentrates, both cows increased sharply in milk
yields, as shown by the curves after point "X" in Figure 8.
Based on these observations, mixed concentrates were offered in
later trials, enabling both milk production and body weights to
be maintained reasonably. Jersey cows yielding a high-solids
milk were used throughout the trials.

28 Daily milk yield on Napier grass
Average yield in 3 previous lactations------
Relurn to herd feeding x-


o, 5343

12 \ ,401

Days in Milk
O 30 60 90 107

Fig. 8.-Relation of milk production of cows 343 UF and 401 UF while
grazing Napier grass without supplemental concentrates, as compared
with conventional concentrate-and-roughage feeding.

The decline in milk production and loss in body weight were
to be expected, since the protein content of Napier grass was

Experiments with Napier Grass 27

insufficient to provide for the cows' needs. Analyses showed the
crude protein of fresh Napier grass leaves for the season to be
2.75 percent. Digestion trials at the Florida station by Kidder
(6) showed later that fresh Napier grass leaves provided 0.8
percent of digestible crude protein and 13.7 to 14.0 percent
of total digestible nutrients. Harrison (2) found 0.8 to 1.2
percent of digestible crude protein and 8.7 to 11.3 percent of
total digestible nutrients in trials conducted in Trinidad, British
West Indies. An investigation in Hawaii (15) showed the dry
matter of Napier grass to contain from 7.9 to 5.6 percent of
total crude protein at the sixth to fourteenth weeks of growth.
1939 Season.-The grazing season during 1939 started April
17 and continued until November 6, 205 calendar days, for a total
of 2,062 cow-days. Six cows were used at the beginning and
the number was increased to 15 at the period of most luxuriant
growth. In August the number was reduced to 10 and in Sep-
tember it was further reduced to six cows until the end of the
season. A milk yield of 64,218 pounds of 4.0 fat-corrected milk
was produced, or an average of 8,027 pounds per acre. It was
computed that grazing supplied 18,523 pounds of total digestible
nutrients, or 2,315 pounds per acre for the season. Slightly
over 54 percent of the requirements for maintenance and milk
production was calculated as coming from the pasture.
1940 Season.-A grazing season of 161 calendar days from
April 29th to October 6 provided 1,647 cow-days of grazing for
16 different cows with a total production of 44,232 pounds of 4.0
of fat-corrected milk. It was calculated that 14,364 pounds of
total digestible nutrients were obtained from the Napier grass
off the eight acres for the 1940 season.
1941 Season.-The 1941 season did not start until May 19,
due to late frosts followed by dry weather in the spring. Six-
teen different cows were used over a 166-calendar-day period
ending October 27 and totaling 1,529 cow-days. During the
season the milk yield was 43,173 pounds of 4.0 percent fat-
corrected milk. A calculated yield of 13,566 pounds of total
digestible nutrients was credited to the eight acres of Napier
grass for the 1941 season.
1942 Season.-The Napier grass was ready for grazing May
1 when seven cows were started. Later six other cows were
added, making a total of 13 cows on the trial during the season
which ended October 26 after 174 calendar days. The Napier
grass provided 1,600 cow-days of grazing for the period. A

28 Florida Agricultural Experiment Stations

milk yield of 36,855 pounds of 4.0 percent fat-corrected milk was
produced. A computation showed that 15,440 pounds of total
digestible nutrients were provided from the pasture for the 1942
1943 Season.-The 1943 season started May 31, the delay being
due to dry weather and a lack of milking cows in a suitable
stage of lactation. Ten milking cows grazed the area for a
total of 855 cow-days and 14 different dry cows were pastured
on the area part of the season to utilize the growth of herbage
for 737 cow-days. In all, 1,592 cow-days of grazing were ob-
tained during 151 calendar days ending October 28. The milk-
ing cows produced 20,729 pounds of 4.0 percent fat-corrected
milk during the period. Total digestible nutrients provided by
the grass for the milking cows amounted to 7,885 pounds, while
the dry cows utilized 6,085 pounds, making a calculated total
digestible nutrient production of 13,970 pounds provided by
grazing during 1943.

A summary of the data for the five-year grazing trial by dairy
cows on fertilized Napier grass is presented in Table 9. The
various grazing seasons started from April 17 to May 31, de-
pending on weather conditions in the spring. Late frosts and
lack of rainfall influenced early-season growth. The close of the
season was determined arbitrarily to allow sufficient time for the
plants to store up nutrient reserves in the roots before frost
so that ample early regrowth would be possible the subsequent
As much as a six-week difference occurred between the times
when Napier grass was at a height for grazing in the spring.
The closing date for each season was arbitrated on appearance
of the grass.
Rates of grazing in cow-days from eight acres of fertilized
Napier are shown season by season in Figure 9. Frost and
weather conditions affected the dates when grazing began or
terminated during each season. Climatic conditions also were
reflected in the period of peak grazing, being later in the third
and fifth trials than during other trials. The Napier grass took
some time to become established, and hence the preliminary year
was not regarded as an integral part of the grazing trials.
Total digestible nutrient yields per acre as computed by in-
verse calculation from live weights of the cows, their milk

SActual Butter- 4.0% fat- Require- T. D. N. T. D. N.
Grazing Season Cow Milk fat Corrected Grain ments for from from
Season Start Close ] Days j Days Produced Produced Milk*** Fed T. D. N. Grain Grazing
I pounds pounds pounds pounds pounds pounds pounds
1939 Apr. 17 Nov. 6 205 2,062 57,907 2,737 64,218 20,904 34,201.6 15,678.0 18,523.6
1940 Apr. 29 Oct. 6 161 1,647 39,931 1,884 44,232 14,337 25,117.4 10,752.8 14,364.6
1941 May 19 Oct. 27 166 1,529 39,196 1,833 43,173 13,933 24,016.3 10,449.8 13,566.5
1942 May 11 Oct. 26 174 1,600 32,626 1,587 36,855 11,238 23,404.3 7,963.6 15,440.7
1943 May 31 Oct. 28 151 855' 18,899" 878* 20,729 6,943* 12,801.4* 4,915.7:: 7,885.7*
1943 May 31 Oct. 28 151 737*-' --- -- ..-......- 6,085.5** -......-.... 6,085.5* :

Total ......8,430 188,559 8,919 209,207 67,355 125,628.5 49,759.9 75,866.6
Data from cows in milk.
** Data from dry cows, used in part because too few milking cows were available to utilize grass.
*** 4.0%o fat-corrected milk is computed on an equal-energy basis, applying the formula of Gaines: Fat-corrected milk 0.4 X milk, plus
15 X butterfat.


Year Grazing Season Calendar Pounds of Dry Matter per Acre
Days Lot 1 Lot 2 Lot 3 Lot 4 Lot 5 Average

1939.-...........-...... April 17 Nov. 6 205 3,847 3,748 3,853 2,986 2,825 3,452
1940................... April 29 Oct. 6 161 2,723 3,069 2,588 2,202 2,193 2,555
1941*': ............. May 19 Oct. 27 166 1,668 1,997 1,834 1,906 1,451 1,771
1942---- .......... --May 1 Oct. 28 174 2,202 2,554 2,046 2,080 1,848 2,146
1943--..........----. May 31 Oct. 28 151 2,292 2,487 1,750 2,263 1,997 2,158

SAverage ....................... 171.4 2,546 2,771 2,414 2,287 2,063 2,416
These are based on averages from yields in three quadrats per lot, stripped by hand to simulate grazing. CO
** Late frost and dry weather delayed Spring grazing.

30 Florida Agricultural Experiment Stations

yields and butter fat percentages varied with the years. It was
computed from the eight-acre totals in Table 9 that the total
digestible nutrients ranged between 1,696 and 2,315 pounds per
acre annually, with an average of 1,897 pounds over the five-year
period. Likewise, the Napier grass samples plucked from caged
quadrats ranged between 1,771 pounds and 3,452 pounds of dry
matter, with an average of 2,416 pounds per acre (Table 10).
It was computed that a pound of dry matter furnished 0.785
pound of total digestible nutrients-a value slightly above the
coefficient of digestibility of Napier grass leaves (66.0 percent)
determined by Kidder (6). This may be explained by the fact
that the cows may have grazed more closely than the forage
samples were plucked for yield estimates. The difference is in
favor of efficiency of the cows in their grazing habits.



9 1941

10 10 9 9 7 7 6

Fig. 9-Average number of cows per acre per tour during the pre-
liminary and five experimental grazing seasons. Differences were observed
in initial, peak and final grazing periods each season, as well as in level
of cow days of grazing during each tour. Cows were added or withdrawn
as forage increased or decreased.


A total of 209,208 pounds of 4.0 percent fat-corrected milk
was produced from the eight-acre area for the five-year period.

Experiments with Napier Grass 31

This was in addition to the maintenance requirements of all
cows. The 1943 season's herbage was utilized partly by milk-
ing cows and partly by dry cows. Grazing days for milking
cows for the entire period amounted to 7,673 cow-days. Thus
a production of 27.26 pounds of 4.0 fat-corrected milk was ob-
tained daily per cow when fed concentrates at the rate of 1
pound of feed to approximately 3 pounds of milk produced.
Excluding the 1943 season, 188,478 pounds of 4.0 percent fat-
corrected milk was produced for four seasons on the eight-acre
area, making an annual production per acre of 5,889 pounds of 4.0
percent fat-corrected milk.
Throughout the five-year period it was computed by standard
methods that the Napier grass on the eight-acre area provided
75,866 pounds of total digestible nutrients, or an average of
1,897 pounds per acre per season. This is equivalent to about
two tons of green leafy grass hay per acre. The season aver-
aged 171 calendar days and 1,686 cow-days grazing. Thus the
total digestible nutrient yield averaged 88.5 pounds per calendar
day and 9.0 pounds per cow-day.

Dr. H. Harold Hume, then associate director, made an 8-acre
area available especially for the Napier grass trials. Frazier
Rogers accurately surveyed the area into 5 equal lots. Dr. A. L.
Shealy and the late W. E. Stokes provided facilities and counsel
during the investigation. Dr. G. B. Killinger assisted in agrono-
mic evaluations during the latter part of the grazing trials.
Analyses of feed and grass samples were supervised in the Nu-
trition Laboratory by Drs. W. M. Neal, L. L. Rusoff and George
K. Davis. Dr. R. B. Becker assisted with the project plans and
preparation of the manuscript. The photograph for Fig. 5 was
made by R. W. Kidder. Graphs were drawn by Alf O. Barth.

1. BURTON, G. W. A New Day for Southern Grasses. So. Seedsman
1(5): 4, 16-17. May-June, 1938.
2. HARRISON, E. Digestibility Trial on Green Fodders. Trop. Agr. (Trini-
dad) 19: 147-150. 1942.
3. HENKE, L. A., and G. W. H. Goo. Comparative Value of Napier and
Sudan Grass when Used as Soiling Crops for Dairy Cows. Jour.
Dairy Sci. 22: 1007-1010. 1939.

32 Florida Agricultural Experiment Stations

4. JOACHIM, A. W. R., and D. G. PENDITTESEKERS. The Effect of Stage
of Maturity on the Composition of Napier Grass. Trop. Agr.
(Ceylon) 89: 264-269. 1937.
5. Joint Committees on Pasture Research. Pasture and Range Re-
search Techniques. Agron. Jour. 44: 39-50. 1952.
6. KIDDER, R. W. Composition and Digestible Nutrient Content of
Napier Grass Leaves. Jour. Agr. Res. 70: 89-93. 1945.
7. KNOTT, J. C., R. E. HODGSON and E. V. ELLINGTON. Methods of
Measuring Pasture Yields with Dairy Cattle. Wash. Agr. Expt.
Sta. Bul. 295: 3-20. 1934.
8. LEUKEL, W. A., and J. P. CAMP. Fertilization of Pasture and Forage
Grasses. Fla. Agr. Expt. Sta. Ann. Rpt. 1935: 41-43. 1935.
9. MORRISON, F. B. Feeds and Feeding, 20th Edit. Morrison Publ. Co.
10. NEAL, W. M., R. B. BECKER and P. T. Dix ARNOLD. The Digestible
Nutrient Content of Napier Grass Silage, Crotalaria intermedia
Silage and Natal Grass Hay. Fla. Agr. Expt. Sta. Bul. 279: 3-26.
11. PATERSON, D. D. Influence of Time of Cutting on Growth, Yield and
Composition of Fodder Grasses. I. Elephant Grass (Pennisetum
purpureum.) Jour. Agr. Sci. 23: 615-641. 1933.
12. RITCHEY, G. E., and W. E. STOKES. Forage and Pasture Grass Im-
provement. Fla. Agr. Expt. Sta. Ann. Rpt. 1937: 45. 1937.
13. SHEALY, A. L., W. G. KIRK and R. M. CROWN. Comparative Feeding
Value of Silages Made from Napier Grass, Sorghum and Sugar-
cane. Fla. Agr. Expt. Sta. Bul. 358: 3-18. 1941.
14. THOMPSON, J. B. Napier and Merker Grasses. Fla. Agr. Expt. Sta.
Bul. 153: 136-249. 1919.
15. WILSIE, C. P., E. K. AKAMINE and M. TAKAHASHI. Effect of Frequency
of Cutting on the Growth, Yield and Composition of Napier Grass.
Jour. Amer. Soc. Agron. 32: 266-273. 1940.
16. WILSIE, C. P., and M. TAKAHASHI. Napier Grass (Pennisetum pur-
pureum), a Pasture and Fodder Crop for Hawaii. Hawaii Agr.
Expt. Sta. Bul. 72: 1-17. 1934.

Full Text


,..,.7JBulletin 568September1955UNIVEIlSITY OF FLOIlIDA M:RICULTUIlALEXPEIlIMENTSTATTOJ\S J.R. BECKENBACH, Director GAn,ESVILLE, FLOIlIDAExperiments with Napier GrassRoyE.BLASER, G.E.RITCHEY,W.G.KIRKandP.T.DIXARNOLDTECHNICALBULLETINFig.l.-\Vell fert.ilized Napier gTa!')sgavesatisfactQI'yreturnsunder rotational g,'azing. Fenced quadrats,as inthe middle foreground, were used in measul'ingforage)!ields.


CONTENTSINTRODUCTIONREVIEWOF LITERATURE ES'I'ABLISHING NAPIER GRASS AdaptationStrains..__ __ __"PropagatingandPlantingFertilization"0_'Cultivation.'0."'.Grazing ManagementAGRONOMIC EXPERTMF;NTSCuttingManagement." Effect ofFertilizationonYieldsQualityofHerbage._.... ..SummaryofAgronomic Phases ..__GRAZING TRIAL,.'" WITHBEEF CATrLE .._..Grasswith HiR'h NitrogenFertilization_..__..__. Chemical CompositionofHeavilyFertilizedNapier Grass ... GrazingLightlyFertilizedNapierGrass .__ __.SummaryofGrazingNapierGrasswith Beef CattleNAPIERGRASS l<'OR DAIRYCOWSPlan of Workwith DairyCows MethodofCalculationGrazingResults...__.._..... Five-YearResults and Discussion SummaryofTrialswithDairyCows _.ACKNOWLEDGMENTSREFERBNCES CTTED FOREWORD PaRe 3 34 4 4 5 6 6777101315 15 151720222222 25 25 28 3031 31 InvestigationswithNapiergrass(Pennisetum p",rpw'eum Schum.)wereconductedatthe AgriculturalExperimentStationsforanumberofyears.Theresultswerenotbroughttogetherpromptlyattheconclusion because of changesandreorganizationofthe staff. Sincethattime, newgrassintroductionsandchangingfertilizerpracticeshavecombinedtolimitthegeneralusefulnessofNapiergrass.However,undertropicalandsub-tropicalconditionswhenaperennialgrassforyear-roundforageis desired,thisgrassstillhasa place.Itis hopedthattheinformationcontainedherewillbeof valueundersuch conditions.


ExperimentswithNapierGrassRoyE.BLASER',G.E.RITCHEY',W.G.KIRK'andP.T.DIXARNOLD'INTRODUCTIONItisgenerallyknownthatquality,reproductionandproductivityinlivestockareassociatedwiththenutrientsin feedstheyconsumeaswellaswithbreedingandmanagement.SomenativeherbageinFioridais lowinnutritivevalue,butnotedimprovementsarebeingmadein feedsupplybyintroducinganddevelopingimprovedforageplants,alongwithgoodculturalandmanagementpractices.NapiergrasswasgrowninFloridalongpriorto1937,butitsvalueasagrazingcrophadnotbeendeterminedpreviously.ThepracticeofcontinualgrazingofNapiergrassresultedinlow yieldsandultimatedestructionofthestand.Consequently,itwasnotconsideredpracticalforpasture.IthasbeendemonstratedthatastandofNapiergrasscanbemaintainedforseveralyearsbyadequatefertilizerapplicationsandrotationalgrazing,asshowninFigureI.Grazingtrialswerestartedin 1937tomeasurethevalueofNapiergrasspastureforfatteningcattle,andin 1938todetermineitsimportanceasagrazingcropfordairycows. REVIEWOFLITERATURENapier grass, PennisetwlnP1l1'pU1"eUm Schum., was first introducedintotheUnitedStatesfromAfricain1913 (1 .. )'.Itis alargetropicalcane-likeperennialwhichgrows7to15feetinheight.Therearemanystraindifferences.NapiergrasswasfirstdistributedtoFloridafarmersin 1915 (14), butisnotgrownextensively. Twofactorswhichlimiteditsuseandpropagationhavebeenimpropermanagementandafungusdisease,"eyespot"(Helminthosporium ocell"mFaris).EyespotwasfirstreportedbyLeukelandCamp(8)in1935.Thisdiseasewasofsuchvirulencethatitdestroyedwholestandsinsome localities.Eyespot-resistantimprovedstrains1NowProfessor of Agronomy, Virginia Polytechnic Institute, Blacks burg, Virginia, "Formerly Agronomist,Divisionof Forage Crops andDiseases.B.P.L.S.A.E.,USDA,Gainesville;mOrerecentlyAgronomistin Charge,SuwanneeValleyAgriculturalExperimentStation,LiveOak, Florida. NowVice-Directorin Charge, Rang'eCattleExperimentStation,Dna,Florida.,AssociateDairy Husbandman, Florida Agricultural Expel'iment Station. Italic figures in parentheses refer to literature cited.


4FloridaAgriculturalExpel'iment Station, ofNapiergrassweredevelopedsubsequentlybyRitcheyandStokes(12)andbyBurton(1).Thisgrasshasbeenusedprimarilyforsoiling(cuttingandfeedinggreen)intropicallocations (3, 4, 11and16).InFlorida,testshavebeenmadetostudyitsvalueforsilage(10,13).Thesilagewasfoundtobeinferiortothatofsorghum,cornorsugarcanewhenonlytwocuttingsweremadeduringthegrowingseason.TherearefewexperimentaldataonthegrazingvalueofNapiergrass.WilkieandTakahashi(16)reportthatoneHawaiianplantationhasusedNapiergrasssuccessfullywhengrazingwasdelayeduntilthegrassreachedaheightofsixfeetandwithopportunityforregrowthaftertheherbagewascon sumed.AnendeavorhasbeenmadebytheFloridaAgriculturalExperimentStationtousethisgrassforhay,butitwasnotpos sibletopreserveitproperlybecauseofdifficultyincuringthecoarse stems.Fromlaterwork,itisevidentthatcombinationsofsome legumeswithsod-forminggrassesproperlyfertilizedandmanagedmayextendthegrazingseasonandalsoreturnmoretotaldigestiblenutrientsperacrethanNapiergrassprovided.ESTABLISHINGNAPIERGRASS ADAPTATION NapiergrassisadaptedwidelyandtherootsandcrownstoleratealltemperatureextremesinFlorida.Thetopsarekilledreadilybyfrosts.Newgrowthfromthecrownsisnotreadyforgrazinguntillatespring.InnorthcentralFloridaitgenerallyfurnishesherbageforgrazingfromMaytoNovember.Thegrassfurnishesgrazingforashortseason,andahighyieldofqualityherbagecanbeobtainedonlyundercarefulgrazingmanagement.Thisgrassisadaptedtoreasonablywell-drainedfertilesoil.Itisproductiveonfertilizedsandysoils,butgrowsprofuselyontheEvergladespeatsoilswhereithasreachedthestatusofa weedonvegetablefarms.Itproducesahighyieldofherbageondrouthysandsoils.STRAINSTherearemanystrainsofNapiergrasswhichdifferindis easeresistance,yield, leafiness andothercharacteristics.This


Experiments withNapier Gmss 5grassproducesseedreadilyinSouthFlorida.Spaceplanting tests showmuchvariability among seedlingplants.Anydesirablecharacteristicsorphenotypeswhichoccurinseedlingplantsneednotbe fixed, sincethis grass usuallyispropagatedbyfootandstemcuttings.Inthebreedingprogramtheprimaryobjectiveshavebeentoproducehigh-yieldingleafystrainsthatareeyespot-resistant.Severalstrainswhichprovedtobegreatlysuperiortomassselectedtypesweretestedinanexperimentunderdifferentmanagementandfertilizerpracticesduringtheperiod 1942to1944. SelectedstrainsofNapiergrassvariedinheightandleafiness,asshowninFigure2.TheaveragegreenyieldsofthreevarietiesforallfertilizertreatmentsshowthatNo.4wasthemostproductivestrain(Table1).Becauseofitsleafinessandproductivity,thisstrainisrecommendedoverothersandhasbeendistributedtofarmers.TABLEI.-RELATIVEGREENWEIGHT YIF..LD PERACREOFTHREESTRAINSOFNAPIER GRASS* 14,686] l'::Ull 11,321 10,729 8,281 7,694 14,88311,979 11,689 --jStrain __ __ F=re"s'i:h Green Forage perAcre19421943 i 1944 ---I-Average-----+--ccp-'ou"n:=dsr poundg j poundsII18,446 13,R24 14,581I LeastSignificant Difference:P-.05 p.014160 167 The of leaves of the three strains didnot differ significantly.PROPAGATIONANDPLANTINGAlthoughNapiergrassproducesseedinSouthFlorida,generallyitispropagatedreadilybyplantingrootstalks(rhizomes)orstemcuttings,Seedlingplantsaredifficulttogrowandtheyusuallyproduceundesirableplanttypes,Stemandrootcuttingsareplantedonetotwofeetapartinrowsspacedfivetoeightfeet,Rootcuttingsarecovered completelywithtwotofiveinchesofsoiLThree-jointstemcuttingsarestuckintothesoil at abouta 450 angleatadepthtoleavetheuppermostnode exposed,


6Florida Ag?'icultural ExperimentStationsTheplantingdateisimportant.RootpiecesmaybeplantedduringFebruaryand March, whilestemcuttingsorrootstalks may be usedduringJuneorJuly.Stemcuttingshavebeenusedsuccessfullyforearlyspringplanting by cuttingthestemsinlatefallbeforefrostandburyingthemdeeply enough indampsoiltoavoiddryingorfreezing.Earlyspringplantingsarepreferred,becauseofless weedcompetitionandhigheryields.Althoughnotestshavebeenmadetostudyseedbedpreparation,itis knownthatathoroughlypreparedseedbedgivesbestresults. FERTILIZATIQI" Itisnecessarytoapplyfertilizerliberallyasfew,ifany,soils in Florida possess a sufficiently highreserveoffertilitytosupportgoodgrowthofNapier grass. Completefertilizers,5.7,6'orsimilarformulas,applied atrates of400to600 pounds pel' acreintherowbeforeplanting,havebeenfoundtostimulategrowthandshortentheperiodofestablishment.Bestgl'owth responsewasobtainedfromnitrogenfertilizers.Growthwasimprovedonthemoreacid soils when lime wasapplied inadditiontothecompletefertilizers.CULTIVATIONNapierg,'ass doesnotshadetheground01'spreadmuchduringthe first year.Thereforeitisnecessarytocultivateatleasttwiceduringthefirst season tocontrol weeds and to augment releaseofnitrogenfromdecayingplantmaterial.Afterthefirst year thenecessityofcultivationwill depend on weediness u These indicateamountsofnitrog'cn, phusphoric acid andpotash,l'espectively, inthefel,tilizel'formulas. Fig. 2.Three strainsofNapiergrass(Nos.4,lGOand 1(;7) wereselectedtoinvestigatefor forage purposes, basedongrowth and leafiness.


Experiments 1vith Napier Grass 7ofthelandandgrowthofthegrass.Onediskingannuallyinearlyspringwithaheavydiskharrowgaveexcellentresultswithpasturesgrazedbybeefanddairycattle. GRAZING MANAGEMENTNapiergrassisa tall,erectplant.Whengrazedheavilyandcontinuously,theanimalsremovetheleaves.Withrathercompleteleafremoval,organicnutrientreserves(starches,sugarsandothercompounds)intherootsandundergroundstemsbecome depletedandnewgrowthisproducedslowlyortheplantsdie.ThestandofNapiergrasscanbemaintainedwell,providedthereisashortgrazingperiod (5to10days)followedbya longre-growthperiod (20to30days).Tomaintainthisgrass,itmustbegrazedrotationallyandfertilized.AGRONOMIC EXPERIMENTSCUTTINGMANAGEMENTThefollowingexperimentillustratestherelationshipbetweenyieldandmanagement.Sevenmanagementtreatmentswerecompared,asshowninTable2.Eachyield isgivenasanaveragefor24plots(threestrainswitheachofeightfertilizers).Thegrasseswerenotcutforyielddeterminationduring1941,topromoteestablishmentofsatisfactorystandsandstorea goodsupplyoforganicnutrientreservesinrootstalks.Thetotalherbageyieldsingreenweightsaregivenfor1942and1943forallmanagementtreatments.In1944 all plotswerecuttwotimestomeasureresidualeffectsofthevariousmanagementtreatmentsonyields.Thetotalgrassyieldswhenstrippedtosimulategrazingatthreefeetandfivefeetwere9,258poundsand8,103poundsperacre,asshownbytheaverageyieldsfor1942and1943.Whenthe g-rass wascutbacktofiveinchestallwheneveraheightofthreeorfivefeetwasreachedtheyieldswere12,065and12,847 pounds, respectively.Theaveragegreenyieldwas16,605poundsperacrefortheplotsthatwerecuttwiceperseason.TheseareshowninTable2.Qualityofherbageismoreimportantthantotalyield.Herbagequalitydependsuponleafiness. Leafinesswasassociatedwithmanagementtreatment,asshownbyanaverageof88to93percentofleavesforplantsstrippedtosimulategrazingand50to53percentofleaveswhencutatheightsofthreetofive


TABLE2.-GREENWEIGHTYIELDSPERACREOFFRESHNAPIERGRASSASAFFECTEDBY SEVEN MANAGEMENTTREATMENTS*ManagementTreatments-on -1:-1-Ii':Ir -I-pounds Leavesstrippedwhengrass3ft. high 10,309 8,206 93 9,258 8,610I19,983Leavesstrippedwhengrass5ft.high9,365 6,841 88I8,103 7,131I!19,704Cutto5incheswhen3ft.hig"h..13,213 10,917 50 12,065 6,032 10,839Cutto5incheswhen5ft.high .... 14,883 10,8105:112,847 6,809 11,755Cutto20incheswhen3ft.high.11,326 9,6766710,5017,036,17.548Cutto20incheswhen5ft.high 112,26910,16057I11,215I6,393I17,345Cuttwotimeduringyear .... 18,580 14,62343I 16,605 7,140 1 12,182LeastSignificantDifference = i_ _1_ 1EachyieldWtl8computedali theaverage froillHplots (8 fertilizers with 8strains).**D'llring1944l1.U plots were harvestelltwu times to measureretlidualeJfeets ofthe managementtreatments.00


ExperimentswithNctpie1'(J'l'aSS 9feet.Anaverageofonly 43percentofleaveswasobtainedwhencuttwiceannually.Guttingthisgrassatinfrequentintervalsresultedintheproductionofhighyieldsofverycoarse,stemmyherbage.Strippinggrasstosimulategrazingreducedyields,buttheherbagewasveryleafy.Totalleafproductionamongthese management treatments was similar. f'ig. 3.-ThestandofNapiergrasswasmaintained well throughout six yearsof rotatlonal grazing. This picture showsthestand in theseventhyear.Yieldstakenduring1944 tomeasureresidualeffectsfrom1942and1943cuttingtreatmentsshowthatgrassplotsstrippedtosimulategrazingorcutto20inchesfromthegroundproducedhigheryieldsthangrassthatwascutbacktothegroundtwiceannuallyorcutafteraheightofthreetofivefeetwasreached.ThisindicatesthatNapiergrassismaintainedin aproductiveconditionwhenthestemsarenotcutbackcompletelyordefoliated periodicallyasingrazing.Highyieldsmaybeassociatedwithhighcarbohydratereservesandpossiblylateralspreadingundergrazingmanagementconditions.It has been


10 }'lo1'ida.4gricultumlExpet'iment Stationsobservedthatnew leaves developrapidlyfromaxialbudsatthenodesalongthedefoliatedstems.ThelongevityofNapiergrassunderrotationalgrazinghasbeendemonstratedingrazingexperimentsconductedwithdairycows.InthesetrialsfivelotsofNapiergrassweregrazedrotationally.Grazingwasinitiatedwhenthegrasswasthreetofivefeetinheight.Thenumberofcowswasadjusted so thatabout90percentoftheleafagewasconsumedinfivetosevendays,afterwhichthecowsweremovedtoanotherlot,insuc cession.Thisallowed 20to28daysforrecoveryaftereachgrazingperiod.Lightgrazingwaspracticedduringthelateseasontopreventexcessivereductionofleafarea,andthusallow a build-upinrootreserves.Underthisgrazingpracticeanexcellentstandofgrasswasmaintainedandthedensityofstandsincreased.Thestandofgrassaftersevenyearsofgrazing is showninFigure3.EFFECTOFFERTILIZATIONONYIELDSTestsdesignedtostudyfertilizerratesandratios,timeofapplication,andsourceofnitrogenongrowthofNapiergrasshavebeenmadeonanArredondofinesandsoil,asshowninTables3, 4 and 5.Theaverageyieldduring1941-1944was1,695poundsofdrymatterwithoutfertilizer,ascomparedwith3,081poundswhen32poundsofnitrogen,64poundsofphosphoricacid (P,O,) and32poundsofpotash(K20)wereappliedannually.Doubleandfourtimesthenitrogenapplicationsincreasedtheyieldsto4,226and8,868poundsofdrymatterperacre, respectively.BecauseNapiergrassisknowntogivesignificantyieldincreasesfromnitrogenfertilization,testswerecarriedontomeasuregrowthresponsesfromsingleannualapplicationscomparedwithseveralsplitapplications. Atotalof64poundsofnitrogenwasappliedinMarchinoneapplicationinoneseriesofplots,andsplitintotwoapplicationsof32poundseachinMarchandJuneinanotherseriesofplots(Table3).Intwoofthefouryearsyieldsweresignificantlyhigherfromthesplitapplication.Thefour-yearaverageyieldwashigherfromsplitnitrogenapplications.Anaverageof4,226poundsofherbagewasobtainedwhen64poundsofnitrogenperacrewereappliedinMarch,ascomparedwith6,079poundsofherbageperacrewhen32poundsofnitrogenwereappliedinMarchandJune.InanotherseriesofplotsnitrogenwasappliedinMarchatthe


TABLE3.-EFFECTOFRATEANDTIMEOFNITROGENApPLICATIONSONDRYMATTERYIELDSOFNAPIERGRASSGROWNONARREDONDOFINE SAND SOILS.Thirty-twopounds ofnItrogen isequivalent to 200 oounds of nitrate of soda, which wastheformuscd inthe test. Thirty-two pGunds of phosphoric acid isequivalentto200 pound:; ofsuperphosphate.Thirty-twopoundsofpotash (K"O) is equivalent to64poundsof f>Opercentmuriate ofpotash, ** The phm;phate and putash wereappliedinMal'cheachyear.when tht'nitrugenwaslls'd in splitapplicationsas indicated.TotalFertilizerApplied*IPhosphoricI... ----Nitrog'enAcidPotash -pounds-poundsLeastSignificantDifference:TimeofNitrogen._ __I,DryMatterperAcre I 19411 1942 I -lpounds-j-poundsl-pounds IpoundspoundsN one II I1,458 II 1,483 \ 2,145 1,695March3,217 2,400 2,938I3,769 3,081March1,14,119 3,496 5,127 4,1624,226March8,422 8,800 10,875 7,375 8,868 32poundsinMarch,June6,381 6,600 5,241I6,164 6,079 32poundsin II __:11 :_::_:_:_ :::::-+--::::: _11 __ 6 '142p -.Dl 3,509 2,183 2,715 1,44632 323232 326464 64 64 6432 64 128 64 128


12 Florida Ag1'icultural Experiment Stations rateof 128 poundsperacreandinfourapplicationsof32 poundsofnitrogeneachinMarch,June,JulyandAugust(Table3).Theyieldswereconsistentlyhigherfortheplots which received allthenitrogeninone application.Averageyieldsforthefouryearperiod were 8,868poundsperacrewhen128 poundsofnitrogenwereapplied in March,ascomparedwith6,142 poundswhenthenitrogenwasappliedinfourapplicationsof32pounds each.Withsplitnitrogenapplications,thatappliedduringJulyandAugustapparentlywasnotutilized efficiently. Yieldtestscarriedonwithnitrogenfertilizersfromdifferetlt sources(nitrateofsoda,sulfateofammonia,ureaandcalciumcyanamid)gavevariableresponsesduringtheindividualyearsoftesting.Thedifferencesinaverageyieldsforthefouryearswerenotsignificant (Table4).Thesevariableyieldresponsesareattributedto differencesinstandandweatherconditions.TABLE 4.-EFFBCT OFNITROGENFROM DIFFERENT SOURCES ON YIELDOF NAPIERGRASSGROWNONANARREDONDOFINESAND 1,073 1,446P-.05..P-.01Sourceof Nitrogen LeastSignificantDifference: .. ... _._-1 _I1941I1942 1943 1944i Averagepounds'pound-;;:poundsill'-pounds-Nitrateofsoda3,217 2,4002,938 6,164 3,680Sulfateofammonia._I3,767 4,254 3,649 5,292 I 4.241 1 I I1--1-11----__ gg I .. Allplots received61pounds of phosphol"icacid(P,..Or;) and poundsof potash(K,..O) Il.nnuaIl:y.except in1944when one-half therateofphosphoric addwasused.pound!> of nitrog-enwas appliedannuallyinMarch,exceptin1944whenan additional32 pounds was appliedinJune.IntheNapiergrassgrazingtestfordairycows, a completefertilizersupplying 30 poundsofnitrogenperacrewasappliedinMarchandadditionalnitrogensidedressingsattherateof30 poundsperacreweremadeduringthegrowingseason (Table5).Thesidedressingwas applied in one application in Maywithtwoofthegrazinglotsandinfourapplicationsof7.5 pounds each in May,June,JulyandAugustintheremainingthreelots.


E.rpe,'iments 'With N apie1' G1'a," 13 Yields ofherbageweresomewhathigherfortheplotswhichreceived allthenitrogeninearlyseason.Thesedataalsosuggestpoornitrogenutilizationfromlateapplications.Thiswouid be expected, sinceNapier grass reachesitspeakinpro ductionduringJunetoAugust.TABLE5.-DRYMATTERYIELDS PERACHEOFNAPIERGRASS LEAVESASINFLUENCEDBYNITROGENApPLICATIONS.THESEYIELDSWEREOB-TAINED FROM QUADRATSINDAIRYPASTURES.Year ILots1and3ILot 5"i Lots2and4 _V.OHhrlS '__ _J_pounds 400poundsof5-7-5 completefertilizerinSpring;and7.5poundsof nitl'ogenafter fil'stfour grazings. --!-----193fJ 1940 3,8502,656i :1,367 2,636Average1941-1944 1941 .,,,'. 1942 19431944_ 500poundsof 6-6-6 completefertilizerinSpring:I--13 0 -poundsofI7.5pounds ofnitrogenafterNitrogenin firstfourgrazings.IMay------1,95-22,124 1,8482,.'3172,021 1,995 i 2,375 2,315 II2,415 2,053! __=_."" Lot5 was not in theseyieldcomparisonsbecause ofaSQilvariability, *'"Latl' il'oatand a dry Springthe initial grazing, QUALITYOFHERBAGE Grazing managementorcuttingstage,throughitseffect onstemminessorherbage,definitely affectsherbagequality.Plantheight,drymattercontent,leafinessandproteincontentofstems,leavesandungrazedresidueofsamplestakenfromthefields usedforbeefcattlegrazingtestsduring1938areshowninTable6.ThedrymattercontentofNapiergrassleaves, sampledbeforegrazing,rangedfrom13.7to22.6percent.Theproportionofleavesvariedfrom25to 45percentunderactualgrazing(Table6).Thestemminesstendedtoincreaseslightlyastheseasonadvanced.Thecrudeproteincontentoftheleafbladesatthetimegrazingstartedvariedfrom9.2to14.4percent,ascomparedwith3.9 to 6.5percentinthestems.The un-


TABLE OF YEAR,HEIGHT,LEAFINESSAND COMPOSITIONOFNAPIERGRASSUNDERGRAZING, AND AS HARVF.STED FOR SIlAGE. NapierGrassCutTwiceAsForSilage-l-'-I1, 2August7I8630.2 23 9.52.7-13,4August5I8726.1258.4 2.4 ___ 1, 2October 25I7624.63012.3 3.5J3, 4October2574 28.43013.7 1__-----j---------,---------'I----N-a-p-i-er-.-G-ra-S-s-B-e-f-o-re-G'-ra-z-i-n-g _ Dates'" IIPlant'II I __ IHeightMatteriLeavesIStemsIHeightIMatterProtein inches 5.6 Ipercent i percentI14.5I G.'l I17.5 5,3 10.4I8.5 13.8 7.3 16.0 5.3 12.5 5.3 16.0 4.716.6 4.7 15.3 4.6 19.8 5.6 19.8 4.2 18.9 5.8 23.1 5.4 23.2 6.2 16 14 19. 20 19 17 19 20 19 23 20 19 22 20I119.1.1percent iinchespercentIpercentIpercentIII1, 2May10, 163816.945I10.4I5.1I3, 4May21,273819.133 'I 9.25.0,1, 2June,13, 244210.23511.8 1 6.23,4July1, 95113.2 33 11.7 5.0 1July205218.4 30 11.4 4.5 2July26 48 13.73011.7 5.2 3Augu,t1 54 14.8 30 10.8 3.9 4August8 47 17.83410.0 4.1 2, 2August15, 22 40 17.2 35 11.6 4.0 3, 4Aug.29,Sept.3 42 19.9 28 10.6 4.9 1, 2Sept.14,213716.23312.2 5.4 3, 4Sept.27, Oct. 4 36 17.62514.4 6.2I,2Oct.15, 18 34 22.6 34 11.6 4.8 3,...._ _Oct.25, :-2c:-6 __ -i-----=2"'-8 22.6 30I13.2 6.5I. -I _I 1 111HIIVVVIGrazing TourAverage Grasssamplesweretalnm on the when thej;{ralSS had been grazed dowD.and cattle were rotated to thi;'next Jot.


E.l'pel'imcntslcUIlNapierGras.'; 15grazedresiduecomposedlargelyofstems,rangedfrom4.2to7.3percentofcrudeprotein.Whenthegrasswascuttwiceannually,asis conventionalforsilage,theforagewas very stemmy,withonly 23to30percentofleaves.Thecrudeproteininstemsvariedfrom 2.'1 to3.6percentandintheleavesfrom8.0to13.7percent.Themanagementtestdiscussedearliershowedthatfrequentcuttingresultedinincreasedleafiness. However, ahigherproportionofleaveswasobtainedundergrazingconditionsthanfromcuttingtreatments.SUMMARYOFAGRONOMICPHASESEyespot-resistantstrainsofNapiergrassweredevelopedfromselected seedlingplants.Betterstandswereestablishedfromspringplantingthanfromlateplantings.Whencuttwiceyearly,highyields ofgrasswereobtainedthatwerestemmy.Yieldsof leafy herbageweresimilarforsevenstrippingandcuttingtreatments.ThestrippedleaveswerehigherincrudeproteinandlowerinfiberthanthestemportionofNapiergrass.Higherratesofnitrogenapplicationsresultedinincreasedyieldsofforageunderuniformcuttingtreatments.Foursourcesofnitrogenproducedsimilaramountsofforage.LessNapiergrasswasproducedafterapplying64poundsofnitrogeninMarchthanfromapplicationsof32poundsofnitrogeninMarchandagaininJune.GRAZINGTRIALSWITHBEEFCATTLEGRASSWITHHIGHNITROGENFERTILIZATIONA 15-acreareaon Leon,PlummerandArredondosandwascleared, plowed,fertilizedandplantedtoNapiergrassinMarch1937. Rhizomesofmassselectedeyespot-resistantstrainsofNapiergrasswereplantedinseven-footrowswhichreceived 400poundsofa 5-7-5fertilizerattimeofplanting.Thereaftercompletefertilizerwasappliedannually and twotofive applicationsofnitrogenattherateof12to16poundsperacreweremadeassidedressings.In1937theareawascultivatedtwicetocontrol weeds.Infollowingyearsthe grass wasdiskedwitha doublediskharrowwhiledormantinFebruaryorMarch ami once be-


16fi'lol'ida AO";cultumlExperimenlStations tweenthe rows in 1938and1939. The growthandstandofgrass wasretarded in some fields byvariation in soilfertility and excessivemoisturedllringcertaintimesofthe year. InJune1937the grass washarvestedforsilage,afterwhichthe areawas fenced into five lotsofthreeacreseach topracticerotationalgrazing. Grazingwas begunwhenthegrassreachedaheightofthreeto fOllr feet.Thenumberofyearlingsteerswasadjustedsothattheywould consumemostoftheblades in five toeightdays.Thesteerswereweighed individually eachtimetheymoved to adifferentlot. Wate,'andmineral supplementswere availableatalltimes.Foul' movable cages 10feetsquarewereplacedineach lot.Thesepreventedthegrassfrombeinggrazed and madeitpos sible to obtain samplesforyieldmeasurementsandchemical analysis.Grasssamples,handstrippedtosimulategrazing,were obtained immediately after the animals were movedtothenextlot.Bestresultswere obtained in 1938whensteermadeanaveragedailygainof1.73poundsandproduced 430 pounds pel'acre(seeFig.4).Thelowestwerein 1940 whenthecattlegainsaveraged290 poundsperacre.Thelow production in 1940 was causedlargelybyasmallertotalapplicationof nitrate ofsoda and lackofcultivationwithsubsequentweed competition.Improperdrainagecausedpartial nooding of Borne fields inL940, Fig.4.-'l'hcse steel'S madesatisfactory gains inweightand condition on Napiergrassgl:azed rotationally.


EJ'periments withNapier Gms8 17Year 1938. 1939 .1940.Ilnd coldinjuryto rhizomesreducednumberofshoots,bothofwhichreducedtheyieldofgrass.Theaveragegrazingdaysandgainsfromfive lotstotaling15acresofheavilyfertilizedNapiergrassgrazedrotationallyduringthe1938, 1939and1940 seasons,aregiveninTable7.AnacreofNapiergrassprovided 235steer-daysofgrazingina season,andcattlemade369 poundsofgain, whichgaveanaveragedailygainof1.57 pounds.TABLE7.-GRAZINGDAYS,GAINS l'ER ACREAND AVERAGE DAILYGAINOFCATTLEONHEAVILYANDLIGHTLYFERTILIZED NAPIF.R GRASSWIlEN GRA7.ED ROTATIONALLY.------,--H-e-a-V-il-y-F-'e-r-t-il-iz-e-dGras8*-j Lightly -Crazing-I Average\,Averagc IGrazingIAverageIAverageDaysGainIDaily Days GainIDailyperAcreperAcreGainI pel' AcreIperAcreI Gain--'-----Ipounds-i-pounds:-I poundR Ipounds 248 I).430I1.73 ] m I m I I Average 23S_I 1 Applied annually in Marcb,-UlOpoundsCif 5.7-5 fertilizer.Additionalnitrate ofsodaapplied,-300poundsin1938, 375pounds in 1939and210 pounda in H.l40.** Appliedannuallyin March,-100pounds 5-7-5 fertilizer. Thestandofgrasswasnot as densein1940asin1938.Theretardationinstandwas affectedbydifferencesinpalatability,whichresultedinsomeplantsbeing oversized. Sinceplantingmaterialwastakenfrommassselectionsofeyespot-resistantNapiergrass,therewerenumerousplantvariationsinsuchcharacteristicsasleafiness, pubescence,heightandthicknessofstems,andproductivity.Observationsshowedthattestanimalshadquitedefinitegrazingpreferences,resultinginovergrazingandreductioninrootreservesandgrowthwithmanyplants(Figure5).Thisindicatesthedesirabilityofusingplantsofuniformstrainswhenconductinggrazingtestswithtallgrowingplants.CHEMICALCOMPOSITION OF HEAVILYFERTILlZEDNAPIERGRASSIn1938and1939samplesfromtheheavilyfertilizedNapiergrassweretakenatregularintervalsforchemical analysis. Movable cages 10feetsquareprotectedtheNapiergrassfor


TABLE 8,--AVERAGl:!; CHEMICAL COMPOSITIONOFHEAVILY FERTILIZED NAPIERGRASS GRAZED IN1938AND 1939 ANDTHEUNGRAZEDRESIDUEIN 1939.Ungrazed Residue, PrimarilyStemsand Sheaths0.290.33 0.33 0.33 0.48 0.250.47 0.48 '.0 l 1.6 2.0 48.832.25.5I12.3 Napier Grass Blades GrazedbySteers --1--'-1---\--12.1 32.4 I 46.2I2.8 12.5I32.6I45.4 2.9I _L .."'45"".8----'_ 13.8YearAveI'age 193019311 1938


Experimentswith Napier Gmss 19 sampling. Samplesofgrassweretakenatthetimethesteerswere moved tothenextlot,afterwhich each cage was placedinadifferentpartofthefield.InTable 8theaveragechemical compositionofNapiergrassgrazedbythesteersin 1938and1939 and oftheungrazedresiduecollectedin1939aregiven.TheNapiergrasseatenbythesteers,primarilyleafblades,averaged12.3percentcrudeproteinon amoisture-freebasis, whiletheungrazedresidue(mostlystemsandsheaths)contained 5.5percentcrudeprotein.Theungrazedresidue was lowerin dry matter,fatandashandhigherin fiberthanthatconsumed by thesteers.Kidder(6) showedthatNapiergrassleaves on a moisturefreebasiscontained 8.4percentofdigestibleproteinand65.4percenttotaldigestiblenutrients.Itwasestimatedthatin 1938steersgrazingheavily fertilizedNapier grass consumedabout107 poundsofgreenforagedaily. SinceNapiergrassgrownin 1938 containedanaverageof 18.9percent dry matter(Table8),thesteersconsumedabout20.2 poundsdrymatterdaily which contained 1.7 poundsofdigestiblecrudeproteinand13.2 poundstotaldigestiblenutrients.Theaveragedailygainpel'steerin 1938 was 1.73 pounds.Thusthe steersconsumed 0.98 pounds digestibleproteinand7.6 pounds totaldigestiblenutrientsperpoundofgain.Shealyand asso ciates(18) showedinthreetrialsthatsteersfattenedindrylot on arationofcottonseed meal,groundsnappedcornand Fig. 5.-Cowsgrazed the Napier grass plantattheleftbut had not touched the tall plantatthe right.


20 PloridaAgriculturalEJ'periment StationsNapiergrasssilageconsumedanaverageof1.1poundsdIgestibleproteinand6.3poundstotaldigestiblenutrientsperpoundofgain.GRAZINGLIGHTLYFERTILIZEDNAPIERGRASSIn1938anadditional 7Y2-acre arealargelyonArredondosandwasplantedtoNapiergrasstomeasureitsgrazingvaluewhenfertilizedatalightrate.Duringtheplantingyearcompletefertilizerandnitrateofsodawereusedtoinsurea goodstandofstrongplants.Becauseofthefavorableseasonandfertilizerused,thisareawasreadyforgrazingbyJune 29.Theareawasdividedintofivelotsof 1112 acreseachtopermitrotationalgrazing.During1938ina 117-daygrazingperiod, two-year-oldsteerswerefedanaverageof2.27poundsof41percentcottonseedmealdailytostudytheeffectofsupplementalfeedongains.Thenumberofsteersrangedfrom10to15,accordingtotheamountofforageavailable.Thesteersmadeanaveragedailygainof1.72poundsand329poundsgainperacre.EachacreofNapiergrassplusthecottonseedmealprovidedfeedfor191steer-days.Averagedailygainissimilartothatmadebysteersonheavilyfertilizedgrass,Table8,andthetotalgainperacreis 101 poundslowerfora 131-dayshorterperiod.Resultsofthispreliminarytrialshowedthatsupplementalfeedingincreasedcarryingcapacityofthepasture.In1939and1940anapplicationof5-7-5fertilizerattherateof400poundsperacrewasmadeannuallyinthespringwithoutadditionalsidedressingofnitrogenduringthegrazingseason.Yearlingsteerswereusedasgrazinganimalsin1939andyearlingheifersin1940.Two-yearresultsshowthatyearlingcattlemadeanaveragedaily gain of1.42poundsandthat155animal-daysofgrazingwerefurnishedperacre,resultinginatotalof219poundsgainin bodyweight.Therewasagradualdecreaseinamountoffeedavailableasthegrazingseasonprogressed.Duringthefirsttworotationsfrom8to10animalswererequiredtoconsumethegrasson 7.5 acres, whileinthefifthrotationfromthreetofiveanimalsweresufficient. AcomparisonoftheanimalgainsperacreontheheavilyandlightlyfertilizedNapiergrassshowsthattheamountofgrassisdependentlargelyupontheamountoffertilizerapplied,


Exper'itnents toith NapieT Grass21 as presentedinTable7.Figure6showsthattherateofstock ing ontheheavilyfertilizedgrasswasoneanimalperacreinMayandSeptember,whilefromJune1to August 31,theheightofthegrowingseason,twoacressupportedmorethanthreeanimals.InthesetwotrialsNapiergrassfurnishedgood grazing fromMayuntilmid-October,or165to176daysannually.Individual weights obtainedeachtimetheanimalsprogressedintherotationshowedaveragedailygainsinexcessof1poundperanimalduringtheentiregrazingseason.The grass waspalatableandnutritioustothecattleundertherotationalsystemofgrazing. ,./---/ / / // //I ,/:Y I2.00 -u 1.50 ...1.00 "' .501940 1939 1938 .00 __MAY1JUN.tJULY1AUG.ISEP,tOCT. 1 NOV.I Grazing SeasonFig. n.-Changes in g'1'8zing capacity(steersperacre)ofheavilyfertilizedNapier grass duringthe HJ38, 1939 and 1940seasons.ConsiderablegrazingwasavailablefrombothheavilyandlightlyfertilizedNapier grass aftertheexperimentalanimalswereremovedinmid-October,buttheforagewasstemmyandcoarse.TheNapierwasleftungrazeduntillateNovembertobuildupareserveofnutrientsintheroots.TheforagewhichaccumulatedfromOctober15tolateNovemberwasgrazedlaterbythebreedingherd.Maturecowsmaintainedtheirbodyweightforseveralweeks ontheaccumulatedgrowthofNapiergrass.


22FloridaAgriculturalExperimentStationsSUMMARY OF GRAZINGNAPIERGRASSWITHBEEFCATTLEResultsofthegrazingtrialsshowthatapplicationofnitrateof sodaduringthegrazingseasonincreasedgrazingcapacityfrom161 to 235cattle-daysperacreandthegainsfrom228to369 pounds.Theaveragedailygainwas1.42 pounds onthelightlyfertilizedgrass,compared to 1.57 pounds ontheheavily fertilizedgrass.ReturnsobtainedfromthesetwomethodsoffertilizingNapiergrasswill depend uponcostofthefertilizerandtheimprovementingradeofthecattlemakingthehighestgains.NAPIERGRASS FOR DAIRY COWSAnareaof8 acres, dividedinto5 lots, wasplantedtomixedstrainsofNapiergrassinMarch1938forevaluationofthiscropwithdairycattle.Themethodofestablishmentwasthesameasforthebeefcattlephase.Afterthefirstyeartheareawas disked onceeachspring.Thiscontrolled weedssatisfactorilyandseemedtostimulateearlygrowth.During1938through1940anapplicationof5-7-5fertilizerattherateof400 poundsperacrewasmadeinMarch.Fourappli cationsofnitrateofsoda weremadeattherateof 12 pounds ofnitrogenperacre.Beginningwith1941thefertilizerpractices werechangedsoasto compare early-seasonnitrogenapplicationwithseveralsplitapplications. A 6-6-6 completefertilizerwasappliedattherateof500 poundsinMarchandanadditional 30 poundsofnitrogenwasappliedinMay ontwolots.Theremainingthreelots(I,3and5) each received 7.5 poundsofnitrogenappliedaftereachofthefirstfourgrazingtours.YieldsforthesetreatmentsaregiveninTable 5.Whengrazingwasdelayeduntilthegrassinlotsreachedthreetofourfeetinheight,thelotsgrazedduringthelastpartofa rotationbecametallandcoarse. To avoidthis,grazingwasinitiatedsomewhatearlyandthecows were movedfromlottolot, allowingaboutthreeorfourdaysineachduringthefirstgrazingtour.Threemovable cages were placed ineachlottoobtainquadratyieldsofgrassandsamplesforanalysis.Thegrassinthecagedquadratswasstrippedbyhandtwice whileeachlotwasbeinggrazed.Thestrippedleavesweretosimulatetheamountsgrazed.PLANOFWORKWITHDAIRY COWSTheareawas dividedintofive 1.6-acre lotstoprovideforrotationalgrazing-theplanbeingtograzeeachlot approxi-


E.?:pm;mentswith Napie?' Grass 23matelyone weekandallowfourweeksforthe grass to grow before being grazed again.Thetimeintervalforrotationwasestimatedbyobservationofthegrowthoftheplantandby behaviorundergrazingwithbeefcattleinthepreceding year.Gateswere placedfrom each lot to a lanewherewater,mineralsupplementandshadewereaccessibleforthecowsatall times. Only one l!;ate was openedat a timeintothelotcurrentlybeing grazed.Ithasbeen pointedoutintheagronomicphaseofthisstudythat ",apier grasshasan upri!:ht growthhabit.Re-growth followinggrazingcomesfromaxial buds alan!: theungrazedsternsorcanes. Too closegrazingreducesthestemsandthenumberofbuds, sothatleafproduction is impaired. Ontheothe.r hand, insufficientgrazingallowsthestemstogrowtall (8 to 16feet)andproducelittleaxialgrowthor desirable leafymaterialwithinreachofthecows.GrazingwasbeguninthespringintheGainesvillearea'whenthegrasswas three.tofourfeettall,andthenumberof grazing animalswasadjustedsoasto leavethegrazedstems at threetofourfeetinheightwhenthecowsweremoved tothenextlot.Thispracticeappearedto allowplentyofbudsforregrowthandyetnotletthesternsgrowtoo tall (seeFig.7).Earlyinthe grazing seaSOnwhenherbagewas limitedfrom8 to10cowswereused.Later,duringtheperiodofmore luxuriantgrowth, six toeightmore cowswereadded to utilize1ThetopgrowthofNapier grassis killedLolhe ground whenthe LClnpcmtUl'c goeslower thanfreezing.Fig.7.-Napiel'grassbefore andafter a grazing' lourby dairycows.


24 FloridaAgriculturalExperimentStationstheforageproduced.Stilllaterintheseason,thenumberofanimalswasreducedtoadjustforthedeclininggrowthrateofthegrassinautumn.Lateinautumnall cowswereremovedinanattempttopermitsufficientregrowthtogenerateadequatenutrientrootreservesforover-winteringandtostimulaterapidearlyspringgrowththefollowingyear.JerseycowsfromtheExperimentStationdairyherdwereusedthroughoutthestudy.Animalsselectedforthisworkwerepastthepeakofproductioninthecurrentlactationandwerematureinmostinstances.Youngercowshadtobe in cludedattimeswhentoofewmatureanimalswereavailableattheproperstageoflactation.Itwasnecessarytouseevendrycows occasionallyin1943toutilizefullythegrowthofherbage.Thecowswereweighedonthreeconsecutivedaysatthebeginningandendofeachtrialandonceweeklyduringthegrazingseason.All cowsweremilkedtwicedailyinthebarnandcompletemilkproductionrecordswerekept.Individualcompositesamplesofoneday'smilkwereobtainednearthemiddleofeachmonthforbutterfatdeterminations.Thecowswereonpasturecontinuouslyexceptforaboutanhourateachmilkingtime.Aconcentratemixturewasfedinthebarnatmilkingtimeattherateofabout1poundofconcentratesto3poundsofmilkproduced-theofferingbeingadjustedatweeklyintervals,whennecessary,tothedeclineinproductionduetoadvancinglactation.Concentrateswerefedinevenpoundsforconvenienceofattendantsatthebarn.Theconcentrateswereamixtureofcornfeedmeal,wheatbran,driedbrewersgrains,driedcitruspulpandcottonseedmeal.Itwascalculatedtocontain17percentoftotalcrudeprotein,13.5percentofdigestibleproteinand75.0percentoftotaldigestiblenutrientsbaseduponaveragecompositionsasgivenbyMorrison(9).Duetowartimechangesinavailabilityoffeed,severalsubstitutionsofingredientswerenecessaryinthe1942and1943seasonssothattheconcentratemixturewascalculatedtocontain16percentoftotalcrudeproteinand70.8percentoftotaldigestiblenutrientsduringthoseseasons.TheinvestigationbeganwithapreliminaryyearwhilethestandofNapiergrasswasbecomingestablished.Evalutionofthegrazingvalueintermsofcow-maintenanceandmilkproducedperacreofcropwascontinuedoverthefollowing fiveyearperiod.Thisdurationtookintoaccountpossibilityofseasonaldifferences(rainfallandtemperature)andageofthe


El'peri",entswith Napier Gmss 25plants.Also alargernumberofrecordstendedtooffsetvariations expectedbetweenindividual cows.METHOD OF CALCULATIONTheinverse calculationmethodwas usedtoestimatetheamountoftotaldigestiblenutrientswhichthecowsobtainedfromNapiergrass.Forthispurposethenutrientrequirementsofeach cowwerecomputedbyapplyingtheMorrisonstandardwithregardtobodyweight,milkyieldandbutterfatpercentage.Therunningaverageweightofeachcowobtainedfromtheweeklyweighingswasusedtocalculatethemaintenancerequirementsfortotaldigestiblenutrientsduringtheweek. Requirementsformilkproductionwerecalculated weeklyfromtheamountofmilkproduced,usingthebutterfattestforthecurrentmonth.Thedifferencebetweenthecalculatednutrientrequirementandthenutrientssuppliedbysupplementaryconcentratesfedduringmilkingtimewerepresumedtohavebeenobtainedfromthepasture.Whenitwasnecessaryto usedry cows tohelp utilizetheforage,therequirementsformaintenance,togetherwiththefactorsforchangesinweights,werecalculated accordingtothemethodofKnott,HodgsonandEllington(7).Thesearethemethodsofcomputationrecommendedinthe"PreliminaryReportonPastureInvestigationTechnique"byajointcommitteeofAmericanSocietyofAgronomy,AmericanDairyScience As sociation andAmericanSociety ofAnimalProduction(5).GRAZINGRESULTSPreliminarySeason-1938.-CrownsofNapiergrassofmixedunselectedstrainswereplantedinMarch.ByJune,sufficientgrowthhadbeenattainedto begingrazing.SincelittlewasknownaboutthebehaviorofNapiergrassundergrazing,andsincethefirst-yearstandwas expected to producesomewhatlessherbagewhile becoming established,itwasfeltthatthisseasonshould beregardedaspreliminary.However, complete recordswerekeptsoastoanalyzetheplanandtomakeanyadjustmentsdeemed advisable beforestartingtheplannedfive-yeartrial.Tencowsstartedthetrialandlaterfourmorewereadded. Atotalof1,218 cow-daysofgrazingwasobtainedduring107calendardaysoneightacresduringthepreliminaryseason. U was calculatedthat1,168 pounds oftotaldigestiblenutrientsperacre wereobtainedandthat53.6percentofthenutrients


20FloridaAgricultural ExperimentStationsrequiredformaintenanceandmilkproductionwereprovidedbyNapiergrass.Itwasestimatedthata cow consumed 70ormorepoundsofNapiergrassdailyper1,000 pounds liveweight.Thisamountprovidedneithersufficientproteinnorenoughtotaldigestiblenutrientstomaintainbodyweightandoptimummilkproduc tion. Two cows (343UFand401UF)onNapiergrassaloneduringthepreliminaryseason droppedinbothmilkproductionandbodyweightuntilabout16 to 18 poundsofmilkwerebeingpro duced daily.Thereafter,bodyweightnolongerdeclined, althoughmilkproductioncontinuedtodecrease.Whenthesetwo cowswerereturnedtotheregularherd,wheretheyreceivedsupplementalconcentrates,bothcows increasedsharplyinmilk yields,asshownbythecurvesafterpoint"X"inFigure8.Basedontheseobservations, mixedconcentrateswereofferedinlatertrials,enablingbothmilkproductionandbodyweightstobemaintainedreasonably.Jerseycows yielding a high-solids milkwereusedthroughoutthetrials.Daily milk yieldonNapiergrossAverage yieldin 3 previouslactations-----" ,. 20Qoo ,. C.", o60 Rl;!turn 10 herd feedingDaysinMilk90107 .-401 1(---Fig.8.-Relationofmilk productionofcows 343UFand 401UFwhile grazing Napier grass without supplemental concentrates,ascomparedwithconventional concentrate-and-roughagefeeding.Thedeclineinmilkproductionandlossinbodyweightwereto be expected, sincetheproteincontentofNapiergrasswas


ExperimentswithNapie1' Grass 27insufficienttoprovideforthecows' needs.AnalysesshowedthecrudeproteinoffreshNapiergrassleavesfortheseasontobe 2.75percent.DigestiontrialsattheFloridastationbyKidder(6)showedlaterthatfreshNapiergrassleavesprovided0.8percentofdigestiblecrudeproteinand13.7to14.0percentoftotaldigestiblenutrients.Harrison (2) found 0.8to1.2percentofdigestiblecrudeproteinand8.7to11.3percentoftotal digesti!>le nutrientsintrialsconductedinTrinidad,BritishWestIndies.AninvestigationinHawaii(15) showedthedrymatterofNapiergrasstocontainfrom7.9to5.6percentoftotalcrudeproteinatthesixthtofourteenthweeksofgrowth.1939Season.-Thegrazingseasonduring1939startedApril17andcontinueduntilNovember6, 205calendardays,foratotalof2,062 cow-days.Sixcowswereusedatthe beghming andthenumberwasincreasedto15attheperiodofmostluxuriantgrowth.InAugustthenumberwasreducedto10andinSeptemberitwasfurtherreducedtosixcows unt.iltheendoftheseason.Amilkyieldof64,218poundsof4.0fat-correctedmilkwasproduced,oranaverageof8,027poundsperacre.Itwascomputedthat.grazingsupplied 18,523poundsoftotaldigestible nut.rients,or2,315poundsperacrefortheseason.Slightlyover54 percent.oftherequirementsformaintenanceandmilkproductionwascalculatedascomingfromt.hepasture.1940Season.-Agrazingseasonof161calendardaysfromApril29thtoOctober6provided1,647 cow-daysofgrazingfor16differentcowswithatotalproductionof44,232poundsof4.0offat-correctedmilk.Itwascalculatedthat14,364poundsoftotaldigestiblenutrientswereobtainedfromtheNapiergrassofftheeightacresforthe1940 season. 1941Season.-The1941seasondidnotstartuntilMay19, duetolatefrostsfollowedbydryweatherinthespring.Sixteendifferentcowswereusedovera 166-caiendar-day periodendingOctober27andtotaling1,529 cow-days.Duringtheseasonthemilkyieldwas43,173poundsof4.0percentfatcorrectedmilk. Acalculatedyieldof13,566poundsoftotaldigestiblenutrientswascreditedtotheeightacresofNapiergrassforthe1941 season. 1942Season.-TheNapiergrasswasreadyforgrazingMay 1whensevencowswerestarted.Latersixothercowswereadded,makingatotalof13 cows onthetrialduringtheseasonwhichendedOelober 26after174calendardays.TheNapiergrassprovided 1,600 cow-days ofgrazingfortheperiod. A


28 FloridaAgricultural ExperimentStationsmilk yieldof36,855poundsof4.0percentfat-correctedmilkwasproduced. Acomputationshowedthat15,440 pounds oftotaldigestiblenutrientswereprovidedfromthepastureforthe1942season.1943Season.-The1943seasonstartedMay31,thedelaybeingduetodryweatheranda lackofmilkingcowsin a suitablestageof lactation.Tenmilkingcowsgrazedtheareaforatotalof855 cow-daysand14differentdrycowswerepasturedontheareapartoftheseasontoutilizethegrowthofherbagefor737 cow-days.Inall, 1,592 cow-daysofgrazingwereobtainedduring151calendardaysendingOctober28.The milk ingcows produced 20,729 pounds of 4.0percentfat-correctedmilkduringtheperiod.Totaldigestiblenutrientsprovidedbythegrassforthemilkingcowsamountedto7,885 pounds, whilethedrycows utilized 6,085 pounds,makingacalculatedtotaldigestiblenutrientproductionof13,970 pounds providedbygrazingduring1943. FIVE-YEARRESULTS ANDDISCUSSIONAsummaryofthedataforthefive-yeargrazingtrialbydairycowsonfertilizedNapiergrassispresentedinTable9.ThevariousgrazingseasonsstartedfromApril17toMay31, dependingonweatherconditionsinthespring.Latefrostsandlackofrainfallinfluencedearly-seasongrowth.Thecloseoftheseason wasdeterminedarbitrarilytoallow sufficienttimefortheplantstostoreupnutrientreservesintherootsbeforefrostsothatampleearlyregrowthwouldbepossiblethesubsequentseason.Asmuchasa six-week differenceoccurredbetweenthetimeswhenNapiergrasswasataheightforgrazinginthespring.Theclosingdateforeachseasonwasarbitratedonappearanceofthegrass.Ratesofgrazingincow-daysfromeightacresoffertilizedNapierareshownseasonbyseasoninFigure9.Frostandweatherconditions affectedthedateswhengrazingbeganorterminatedduringeachseason. Climatic conditions alsowerereflectedintheperiodofpeakgrazing,beinglaterinthethirdandfifthtrialsthanduringothertrials.TheNapiergrasstooksometimetobecomeestablished,andhencethepreliminaryyearwasnotregardedasanintegralpartofthegrazingtrials.Totaldigestiblenutrientyieldsperacreascomputed by inversecalculationfromliveweightsofthecows,theirmilk


75,866.6IT.D. N. IfromI Grazing-poullcfs18, 14,364.613,566.515,440.778857'" TABLEg.-INTENSITYOFGRAZING,MILKPRODUCTION,SUPPLEMENTALCONCENTRATESANDNUTRIENTSOB'.PAlNEDBYDAIRYCOWS l"ROM EIGHTACRESOFNAPIER GRASS GRAZEDROTATIONALLYDURINGFIVESEASONS, I ... I IActualI I 4.0%fat I-T T:n.N. __ Graz0g Cow MIlkfatI CorrectedGrain mentsforfrom StartICloseI Day..,; IDaysIProducedProducedMilk***FedIT. D. N.Grain ,'--.-----1----1-poundspound;'I --poun(!S-poundspounds r pounds 1939 Apr.17Nov.6 205 2,062 57,907 2,737 64,218 20,904 34,201.6 15,678.0 1940Apr.29Oct. 6 161 1,647 39,931 1,884 44,232 14,337 25,117.4 10,752.8 1941May 19 Oct.27166 1,529 39,196 1,833 43,173 13,933 24,016.3 10,440.8 1942May11Oct.26 174 1,600326261,587 36,855 11,238 23,404.3 7,963.6 1943 MayS!Oct.28[151 855* 18;899':'87f!"" 20,729 6,94:3'" 12,801.4* Oct.28 151 737"1I..6,085.5"'1TotaL 1__ 8,43Q. 1-18;,550 8,919 .1209,g.c:::*1'*4.0',';'fat-correct.ed milk iRcomputed onan ellllalenl".u:Y haHis,:lpplying'theforMulaofFllt-('orre<'tl'tl milk '---0.1 Xmilk, plUH I r, Xbutterfat. ;;::-. TABLElO.-YIELD ESTIMATES OFNAPIER GRASSOF THEFIVELOTSGRAZEDBYDAIRY 3,4522,5551,771 2,146 2,158April17 Nov. GApril29 Oct. {-i May H,l Oct.27May1Oct. 28May31Oct. 28Gl'al.inK Season I -"7',,Poundsof Dry Mattel'perAcreLot1 -.J1-ot..2_I Lot 3 1-Lot4I I205 3,8473,748 3,85:32,986 2,825IIII161 2,723I3,069 2,588 2,202 2,193 166 1,668 1,9971,8341,906 1,451I174 2,202 2,554 2,0462,080 1,848I151 2,282 2,487 1,750 2,2631,m)7 I 1--.2,-5:6-' 2,414[2,287 -11939 .. 19401941**_1942 1943 al'ebaspd onavera .. from yield:; inthree quadrats perlot. ;;trippcd hy hand to I:limulate g"mzing.... Late frostanddry weather delayedSpringgrazing.


30 Plorida Agricultural ExperimentStationsyieldsandbutterfatpercentagesvariedwiththeyears.Itwascomputedfromtheeight-acretotalsinTable9thatthetotaldigestiblenutrientsrangedbetween1,696and2,315poundsperacreannually,withanaverageof1,897poundsoverthefive-year period. Likewise,theNapiergrasssamplespluckedfromcagedquadratsrangedbetween1,771 poundsand3,452 poundsofdrymatter,withanaverageof2,416poundsperacre(Table 10).Itwascomputedthata poundofdrymatterfurnished0.785poundoftotaldigestiblenutrients-avalueslightlyabovethecoefficientofdigestibilityofNapiergrassleaves(66.0percent)determinedbyKidder(6).Thismaybeexplainedbythefactthatthecowsmayhavegrazedmorecloselythantheforagesampleswerepluckedforyieldestimates.Thedifference is infavorofefficiencyofthecowsintheirgrazinghabits.I 9 IIIrIIIIIIIIl.940IlIII IlIIrIrl II 'r ;;0:I :: I f Q tU I Q I ....l z o. I 1_ >Q,GrozinQ fours, days 10 APR 10MAYJUNEJULY AUO'" OCTFig. numberofcowsperaCl"epertourduringthepreliminaryand five expcl'lmentalgrazing seasons.Differenceswereobserved in initial,peakand final grazing periodseachseason,aswellasin levelof cow daysofgrazing during each tour. Cowswereadded or withdrawnasforageincreasedordecreased.SUMMARYOFTRIALSWITHDAIRY COWSAtotalof209,208 poundsof4.0percentfat-correctedmilk was producedfromtheeight-acreareaforthefive-year period.


E,rperimentswithNapierGrass 31Thiswasinadditiontothemaintenancerequirementsofall cows.The1943season'sherbagewasutilizedpartlybymilkingcowsandpartlybydrycows.Grazingdaysformilkingcowsfortheentireperiodamountedto7,673 cow-days.Thusaproductionof27.26 poundsof4.0fat-correctedmilkwasobtaineddailypercowwhenfedconcentratesattherateof1poundoffeedtoapproximately3 poundsofmilkproduced.Excludingthe1943 season, 188,478 poundsof4.0percentfatcorrectedmilkwasproducedforfourseasonsontheeight-acrearea,makinganannualproductionperacreof5,889 poundsof4.0percentfat-correctedmilk.Throughoutthef,ve-year perioditwascomputedbystandardmethodsthattheNapiergrassontheeight-acreareaprovided 75,866poundsoftotaldigestiblenutrients,oranaverageof1,897 poundsperacreperseason.Thisisequivalenttoabouttwotonsofgreenleafygrasshayperacre.Theseasonaveraged171calendardaysand1,686 cow-daysgrazing.Thusthetotaldigestiblenutrientyieldaveraged88.5poundspercalendardayand9.0 poundspercow-day.ACKNOWLEDGMENTSDr. H.HaroldHume,thenassociatedirector,madean8-acreareaavailable especiallyfortheNapiergrasstrials.FrazierRogersaccuratelysurveyedtheareainto5 equal lots. Dr. A. L. ShealyandthelateW.E.Stokes provided facilitiesandcounselduringtheinvestigation.Dr.G.B. Killingerassistedin agrono micevaluationsduringthelatterpartofthegrazingtrials.AnalysesoffeedandgrasssamplesweresupervisedintheNutritionLaboratorybyDrs.W.M.Neal, L. L. RusoffandGeorgeK.Davis. Dr. R.B.Beckerassistedwiththeprojectplansandpreparationofthemanuscript.ThephotographforFig.5wasmadebyR.W. Kidder.GraphsweredrawnbyAlfO.Barth.LITERATURECITED1.BURTON,G. W. ANewDayfor Grasses. So.Seedsman1(5):4,16-17. May-.June, 1938.2.HARRISON,E.DigestibilityTl'ial onGreenFodders.Trap.Agr.(Trinidad)19:147-150. 1942. 3. HENKE,L. A., andG.W. H. Goo. ComparativeValueofNapierandSudan GrasHwhen Used aH Soiling Crops for Dairy Cows. Jour. Dair}' Sci. 22:1007-1010. 1939.


32FI01'ida Agricultur'alExperimentStation .. The Effect of Stagf Trap.Agr.4. JOACHIM,A.W.R,andD.G.PENDITTESEKERS.ofMaturityontheComposition of Napier(Ceylon) 89,264-269. 1937.5.JointCommitteesonPastureResearch.PastureandRangeRe seH-reh Techniques.Agron.Jour.44: 39-50. 1952.6. KI:DDER, R.W. CompositionandDigestibleNutrientContentofNapierGrassLeaves.Jour, Agr. Res.70:89-93. 1945.7. KNO'l'T, J.C.,R.E.HODGSONandE.V. ELLINGTON.MethodsofMeasuringPastureYieldswithDairy Cattle. Wash.Agr.Expt.St.Bul.295:3-20. 1934.8.LEiUKEL,W.A.,andJ.P.CAMP.FertilizationofPastureand Forage Grasses.Fla.Agr.Expt.Sta.Ann.Rpt.1935:41-43. 1935.9.MORRISON, 1". B. Feeds and l<'eeding, 20thEdit. Morrison Publ.Co.1936.10.NEAL,W. M., R. B. BECKER andP.T.DIX ARNOLD'. TheDigestibleNutrientContentofNapierGrassSilage, Crotalaria intermedia SilageandNatal GrassHay. Fla.Agr.Expt.Sta.Bul.279:3-26.1935.11.PATERSON,D.D.InfluenceofTimeofCuttingonGrowth,YieldandCompositionofFodderGrasses.1.ElephantGrass(Pennisetum pU1pnreum.) .Jour. Agr. Sci.23:615-641. 1933. 12.RITCHEY,G.E.,andW.E.STOKES.F.orageandPastureGrassImprovement.Fla.Agr.Expt.Sta.Ann.Rpt.1937:45. 1937. 13. SHEALY, A. L.,W.G.KIRKandR.M.CROWN.ComparativeFeedingValueof Silages MadefromNapierGrass, Sorghum andSugarcane.Fla.Agr.Expt.Sta.Bul. 358: 3-18. 1941. 14.THOMPSON,J.B.NapierandMerkerGrasses.Fla.Agr.Expt.Sta.Bul.153:136-249.1919.15.WILSIE,C.P.,E.K.AKAMINEandM.TAKAHASHI.EffectofFrequencyofCuttingontheGrowth.YieldandCompositionofNapierGrass.Jour. Arner. Soc.Agron.32:266-273. 1940. 16. \VILSIE., C.P.,andM.TAKAHASHI.pureum),aPastureand Expt.St.BuJ. 72: 1-17.1934.NapierGl'ass (Pennisetumpur CropforHawaii.HawaiiAgr.