Group Title: Fort Pierce ARC research report
Title: Legumes vs. fertilizer nitrogen in tropical pastures
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Permanent Link: http://ufdc.ufl.edu/UF00056020/00001
 Material Information
Title: Legumes vs. fertilizer nitrogen in tropical pastures
Series Title: Fort Pierce ARC research report
Physical Description: 7 leaves : ill. ; 28 cm.
Language: English
Creator: Kretschmer, Albert E ( Albert Emil ), 1925-
University of Florida -- Agricultural Research Center
Publisher: University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research Center
Place of Publication: Fort Pierce
Publication Date: [1974]
 Subjects
Subject: Grasses -- Fertilizers -- Tropics   ( lcsh )
Grasses -- Fertilizers -- Florida   ( lcsh )
Plants, Effect of nitrogen on   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Albert E. Kretschmer, Jr.
General Note: Caption title.
General Note: "January, 1974."
 Record Information
Bibliographic ID: UF00056020
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 02934072

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
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(EDIS)

site maintained by the Florida
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Copyright 2005, Board of Trustees, University
of Florida






S1L Fort Pierce ARC Research ileport RL-1974-1


LEGWUMS VS. FERTILIZER NMITROCGE IN-ROPI pjLLESUBRARY

Albert E. Kretschmer, Jr.- Pi 1974


1.O i1..S. Univ. of Ficrida
Climates of tropical areas in Latin America can e asste U
as: (1) desertic, (2) definite dry period without rain for 3-6 months per
year, (3) year-round rainfall, and (4) subtropical (mountainous areas with
rainfall patterns similar to (2) or (3).

Soil differences which modify climatic differences are extremely large
among countries, provinces, and even within local farming zones. Physical
differences such as perieability and particle size are important factors of
drainage and influence pasture plant types that are best adapted. Chemical
differences in soil acidity, toxic elements such as aluminum and manganese,
and deficiencies particularly of phosphorus and nitrogen modify and are
very important in pasture plant growth.

A further modifying influence on beef cattle production is the type
of pasture being used and the grazing management needed to obtain mtinmim
animal yields. Furthermore, animal programs such as cow-calf versus
fattening require mar'eedly different management systems.

In the succeeding presentation, I wish to limit my remarks primarily
to research results of tropical grass pasture growth as influenced by
nitrogen fertilization and results of tropical legume-grass mi:.tures here
no fertilizer nitrogen is applied. No attempt was made to relate this to
dairy cattle or milk production.
FITPOGEH FERTILIZATION

Effect on Grass and Beef Yields

Results of iany clipping experiments with various grasses in the
tropics and subtropics have shown that ma-wimun yields generally are 2/
reached with total annual nitrogen applications of about 500 to 600 1g/ha-'
(assuming other elements are not limiting). Although the maximum response to
nitrogen does not differ greatly among grass species, total annual grass


i/ Agronomist, University of Florida, I AS, Agricultural Research Center,
Fort Pierce, Florida.


2/ 1 kg/ha = 1 kilogram per hectacre = 0.89 pounds per acre






-2--


yields vary widely depending on species, frequency of cutting (or presumably
stockl:ing rate) and height of cutting. A survey of the literature shows that
dry weight yields of tropical species such as Pangola (Digitaria dectuLbens),
Elephant (Pennisetum p4urreum), Guinea (Panicum maximuam), ahod3estCh1_ oris
gayana), Jaragua iyparrhnia rufa), Aler'an (EchinocMhoa polystacha)7
molasses (Ielinis Ainutifflora) a- d African ta beuda Tiynodan nlemfuensis)
respond more to higher rates of nitrogen application than Carpet (Aono-pUs
affinis, A. Compressus), en Bahia (Paspalma notatum). Yields as hifh as
IS metric tons per hectareJ/ per year have been reported. Normal yields,
however, for nitrogen applications of 500 :g/ha/yr. range from about 10
to 30 metric tons per hectare; or if annual production were evenly distri-
buted from about 50 to 80 "tg/ha per day.

Recent research results have indicated that beef production of greater
than 2000 kg/ha/year is possible using these high nitrogen rates if
irrigation and pasture and herd management are highly developed. After
reviewing more than 60 individual beef gain e:-perimental results in the
tropics and subtropics, it was found that about 500 to 1,400 ,kg/ha/year of
beef could be produced with applications of 300 to 500 g/ha/year of
nitrogen applied to grass pastures. Beef production on grass not receiving
nitrogen varied from about 100 to 10O0 :,g/ha/year with most of the results
ranging from 150 to 250 :-g/ha/year. The range for 100 o g/ha/year of
nitrogen applied uas between about 350 and 500 g/ha/year. It was evident
that at the higher nitrogen rates there vere larger variations in beef
yields. This indicates that the limitation of soil nitrogen (soil fertility)
becomes less and less influencial as nitrogen applications increase. The
approximate relationship between nitrogen rates and beef yields are pre-
sented in figure 1. The general range of beef production that aight be
expected from applications of up to 500 'g/ha/year of nitrogen are shoun
(solid lines). Although a straight line relationship probably exists
between nitrogen rate and beef production at the lower rates, this
relationship would 'e expected to be curvilinear (less response to increas-
ed nitrogen rates at the higher nitrogen rates) at the higher rates near
rarximuB grass response to nitrogen and ina:cizau stocking rates. In
addition to the solid lines, the average is shotn by a broken line in
order to determine the approximate value zf legume-grass_ mi-ctures. This
aspect will be discussed later.

Advantages and Disadvantages

Grasses respond rapidly to nitrogen application. Where soil moisture
and other fertilizer elements are not limiting, the use of nitrogen can
help to provide additional feed in periods of pasture shortage. Under
conditions when pasture crude protein contents are very low (below about
7 percent on a dry matter basis), larger animal consumption of grass can
occur when nitrogen is applied. Under these stress conditions, better
utilization-ofrthe-pasture is generally necessary. On the other hand,


1/ 48 metric tons per hectare = 43,000 kg/ha.






-3--


there is very little evidence that beef gains per head, per se, are
influenced marLedly by nitrogen applications (except under conditions
of over-stoc3ing); or that the nutritive value of the pasture is
enhanced (unless protein levels are very low). Generally, stocking
rates can and should be increased with increasing nitrogen rates.
This results (up to a certain point) in increased beef production
per area.

The main disadvantage of nitrogen fertilization is its cost and the
economic implications, i.e., would it be more economical to buy more
land than apply large rates of nitrogen, etc. Historically, nitrogen
use increases in areas as cattle production intensifies. However, this
trend may not continue at the same rate because of the recent large
increases in nitrogen fertilizer costs which, in Florida are almost
twice those for 1972.

An alternate in the use of nitrogen is to incorporate a legume into
the grass pasture. This addition will increase the nutritive value as
well as the carrying capacity.

USE OF LEGCTr ES

Tropical Pasture Production

The value of temperate legumes such as red and white e clover is vell-
nown. Aside from the production of nitrogen that can be utilized by
the accompanying grass, there are uninown factors that help increase
beef production and assure higher reproductive rates in cous. The
'nowledge of tropical legumes in pasture programs of the tropics is
less advanced. .Thite clover normally grows in combination with shorter
temperate grass species (ryegrass, etc.), or in the subtropics during
cooler periods of the year when the accompanying tropical grass is
dormant. ia:imuna tropical legume growth, however, occurs during hot
periods when tropical grass growth also is at a muaimun. Competition
by the grass for light, moisture, and soil nutrients makes it difficult
to establish and maintain a legume in the pasture.

Tropical leguaes have been used successfully on a commercial basis in
A :tralia, Africa, United States (Hawaii and Florida), Latin America,
and elsewhere. Lost of the success has been with the use of trailing,
perennial tropical legumes such as tropical ;udzu (Pueraria phaseoloides),
Centro (Centrosema pubescens), perennial glycine (Glycine wightif), and
more recently Siratr6o -haseolus atropurpureus = i:acroptillium atropurpureum).
These can climb the stems of grasses to obtain sunlight and compete with
the taller grass species. Desmodium species, generally less trailing than
the above, also have proven to be adaptable. The genus Stylosanthes
provides an abundance source of annual and perennial species that are
mostly herbaceous, non-trailing, and probably less competitive-under low
stocking rates.

The least success with these legumes (except possibly tropical Kudzu)
in Latin America appears to be in areas vith high soil fertility (nitrogen)
with high, year-round rainfall, In a similar high-rainfall climatic zone
in Australia, however, udzu, Centro, and Stylo are yeing successfully








used commercially.


It has been stated that tropical legumes can fix up to 500 'g/ha/year
of nitrogen. Generally values of 100 to 200 appear more realistic when
experimental results are evaluated.

In table I are presented various results of small plot cutting experi-
ments where grass alone was compared with grass-legume mixtures. These
data are limited and do not include numerous Australian results. Dry weight
yields of mixtures generally ranged from about 5 to 20 metric tons per
hectare. It appears that yields of about 10 tons would be the commercial
potential with a legume content of the mixture from 25 to 50 per cent on a
dry matter basis. Crude protein (in the harvested plant material) generally
ranged from about 800 to 1,500 and averaged 1,100 %g/ha/year.

In an effort to obtain the value of legumes in tropical pastures, beef
yields obtained in 40 separate experiments (including 13 where white clover
was included as the only legume or in mixture with tropical legumes) were
mar-ed on the dotted line in figure 1. This dotted line represents the
average beef gains per hectare per year on grass pastures receiving different
rates of nitrogen fertilizer. These legume-grass data can be examined in
relationship to the quantity of nitrogen that was needed on grass pastures
to produce the same quantity of beef and thus give an indication of the
value (in terms of nitrogen applied to grass alone) of the legu~ne component.
Because of the diversified type of data obtained, some of the beef gains
from legume-grass mixtures were lower than that plotted for grasses alone
without nitrogen. A majority of legume-grass beef yields were equivalent
to about 50 to 200 !g/ha of nitrogen per year. A majority of mixtures where
white clover was the legume component produced beef at rates equivalent to
100 to 300 pounds of nitrogen applied to grass alone.

Advantages and Disadvantages

Probably the main characteristic advantage of tropical legumes is
their ability to fix nitrogen. A second advantage is that legume quality
digestibilityy and intake by cattle) does not decrease as rapidly with
increasing age as that for tropical grasses. A third advantage is that
intake of tropical legumes by cattle is greater than that of tropical
grasses at the same level of digestibility. Since legume digestibilities
generally are equal to or higher than those of grasses of the same age,
better animal performance would be expected with legume-grass pastures
than for grass alone.

Although obtaining seeds of many of the successful tropical legumes
is difficult, the major disadvantage of tropical legumes is that the
establishment and maintenance of them appears to require too much time
and effort for many ranchers. A further disadvantage is that maximum
stocking rates on legume-grass pastures will generally be lower than those
on highly fertilized grass pastures.

It is generally agreed that as grass competition increases, tropical
legume persistence decreases; also evidence indicates that it is easier
to maintain a league in grass pastures when cool weather, infertile soil,
or an annual dry season exists. It has been difficult to establish






-5-


significant quantities of legumes in the tropical rain forest creas of
Latin America, vrith the possible exception of tropical 'Tudzu. Establish-
ment of more legume species can be more easily accomplished in the
tropical vet-dry zones or in the subtropics, and even in the zones vith
500 to 750 mm of rainfall.

At present in Latin Americabeef cattle production is almost entirely
based on grass pastures. There is a great opportunity to incorporate a
tropical legume in tiny of these pastures to increase pasture carrying
capacity and quality.








Figure 1. Beef production as affected by nitrogen applications
1300 to grass pastures and by legume-grass pastures without
nitrogen fertilization.



1100
lloo



900



700



500 -


4 I -Beef yield from legume+

300 tropical grass pastures.
-Beef yield from white
clover + tropical grass
or white clover + tropical
00 legume + tropical grass
Pastures.


100


200


300


NITROGEN APPLIED TO GRASS--Kg/Ha/Year






-7-


Table 1. Annual dry matter and crude protein yields
of grasses alone and grasses in mixtures
with tropical legumes for selected locations


Country

Colombia


NONE
D. canum/
Centro
D. intortum


Grass


Legume

Calopol/
Clitoria ternatea
D. intortym 2/
Glycine 3/
Kudzu tropical/

NONE
Glycine
Centro 2/
Siratrao
S. humilis'7

NONE
Glycine
Centro
Siratro
S. humilis

NONE
Glycine
Centro
Siratro
S. humilis

NONE
Glycine
Centro
Siratro

NONE
Kudzu tropical

NONE
D. intortum


Nitrogen
Applied
kg/ha/yr.


africana
africana
africana
africana
africana


Pangola
various
various
various
various

Guinea
Guinea
Guinea
Guinea
Guinea

Estrella
Estrella
Estrella
Estrella
Estrella

Pangola
Pangola
Pangola
Pangola
Pangola

Jaragua
Jaragua
Jaragua
Jaragua

Elephant
Elephant

Pangola
Pangola

Pangola
Pangola
Pangola
Pangola


YIELDS
Dry Matter Crude


Metric
Tons
Per ha/yr.

6.8
6.0 to 18.0
12.0 to 14.0
10.0 to 3.0
11.0


15.5
21.1
19.1
24.8
18.5

11.5
15.0
13.8
15.3
12.9

8.3
15.3
14.5
16.4
9.4

13.8
16.7
17.8
21.8

26.5
13.7

3.8
10.8

5.3
5.8
10.3
23.7


Protein

kg/ha/yr.


660
1110
1130
1510
1210

420
1120
1030
lo4o
860

320
980
1010
1080
300

470
1180
1080
1220

1998
1082

260
1910

119
338
863
2325


300
0

0
0


Costa Rica


Puerto Rico


Hawaii







Table 1. (continued)


Nitrogen
Applied
Legume Grass kg/ha/yr.


YIELDS
Dry Matter Crude
Metric Protein
Tons
per ha/yr. kg/ha/yr.


NONE
D. canum
Centro
D. intortum


ARC, Ft.
Pierce,
Florida


NONE
NONE
D. intortum 2/
L. heterocarpon-"
Siratro
S. humilis 7
Hairy indigoY/
Glycine

NONE
NONE
D. intortum
D. heterocarpon
Siratro
S. humilis
Hairy indigo
Glycine


Elephant
Elephant
Elephant
Elephant

Pensacola
Pensacola
Pensacola
Pensacola
Pensacola
Pensacola
Pensacola
Pensacola


Pangola
Pangola
Pangola
Pangola
Pangola
Pangola
Pangola
Pangola


Calopogonium mucunoides
Desmodium
-Glycine wightii
Pueraria phaseoloides


5/ Centrosema pubescens
6/ Phaseolus atropurpureus =
Macrotilium atropurpureum
/ Stylosanthes humilis


0
126
0
0
0
0
0
0

0
126
0
0
0
0
0
0


Country


bahia
bahia
bahia
bahia
bahia
bahia
bahia
bahia


5.3
10.0
10.5
23.3

2.6
9.1
12.4
9.9
8.4
7.9
5.9
6.3

2.1
5.7
12.7
8.8
8.4
7.9
5.4
5.6


125
794
806
2175

147
404
1395
946
1064
888
587
671

163
545
1540
915
900
810
547
629


1/




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