Annual legumes to complement warm-season perennial grass forage systems in north Florida

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Annual legumes to complement warm-season perennial grass forage systems in north Florida
Abbreviated Title:
2009 Florida Beef Report
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Book
Creator:
Foster, Jamie
Adesogan, Adegbola
Carter, Jeffrey
Sollenberger, Lynn
Myer, Robert
Blount, Ann
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Institute of Food and Agricultural Sciences, University of Florida
Place of Publication:
Gainesville, Fla.
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University of Florida
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Annual Legumes to Complement Warm-Season Perennial Grass Forage
Systems in North Florida

Jamie Foster1
Adegbola Adesogan
Jeffrey Carter
Lynn Sollenberger
Robert Myer
Ann Blount


This study indicated that cowpea and soybean are promising quality forages for hay and haylage
production in North Florida


Summary
This study determined the herbage mass, leaf-to-
stem ratio, and nutritive value of soybean
[Glycine max (L.) Merr.], cowpea [Vigna
unguiculata (L.) Walp.], and pigeonpea
[Cajanus cajan (L.) Millsp.] grown in North
Florida. Forages were grown in each of four
blocks in three yr and harvested biweekly until
the recommended maturity stage. Herbage mass
of the forages increased ;ihmni gh the growing
season, and at the respective maturity stages
soybean (3.8 tons dry matter (DM)/ac) and
pigeonpea (3.9 tons DM/ac) had greater
herbage mass than cowpea (2.3 tons DM/ac).
Leaf-to-stem ratio decreased with maturity after
a slight initial increase in all forages. At
harvest, pigeonpea contained 12% crude protein
(CP; DM basis) and 35% in vitro true DM
digestibility (IVTD), soybean contained 18% CP
and 73% IVTD, and cowpea contained 19% CP
and 69% IVTD. Soybean and cowpea have
potential to provide high quality forage to
livestock in North Florida.

Introduction
In Florida and much of the Southern USA,
bahiagrass [Paspalum notatum Fliigge] and
bermudagrass [Cynodon dactylon (L.) Pers.] are
the main pasture forages. However, their
availability for winter grazing is limited and
their digestibility and CP concentration are often
insufficient for growing and lactating cattle in


mid-to-late fall. Warm-season legumes can
provide the needed supplementary nutrients, and
when stored as hay or haylage, they can be fed
in the winter to supplement stored and
stockpiled grasses. The increasing costs of fuel
and fertilizer have made such legumes more
attractive to producers and necessitated
evaluation of their yield and nutritive value. The
objective of this study was to compare the
herbage mass, chemical composition, IVTD, and
leaf-to-stem ratio of cowpea (cv. 'Iron clay'),
soybean (cv. 'Pioneer 97B52') and pigeonpea
(cv. 'GA-2').

Materials and Methods
In each of three yr, cowpea, soybean, and
pigeonpea were grown at the North Florida
Research and Education Center in Marianna, FL.
Each legume was grown on a replicated plot
within each of four blocks. The field was
prepared by plowing and fertilizing with P and
K to soil test recommendation. Immediately
prior to planting, seeds were inoculated with the
appropriate rhizobia and drilled at 50 lb/ac and
6-in row spacing. Planting dates for yr one
(2005) and two (2007) were 9 and 10 May,
respectively.

Duplicate forage samples were taken from each
plot with mechanical clippers from a 0.2-m2 area
and harvested to a 2-in stubble height after


2009 Florida BeefReport










plants reached approximately 11 in height.
Sampling continued every 2 weeks until harvest
at the following recommended maturity stages:
pods began to turn yellow for cowpea (Twidwell
et al., 2002), pod setting for pigeonpea (Le
Houerou, 2006), and stage R6 (full size seed in
pods at one of the four uppermost nodes and
completely unrolled leaves) for soybean
(Sheaffer et al., 2001). Leaf-to-stem ratio was
measured on duplicate samples from each plot
after removal of leaves at the node. Samples
were ground and analyzed for CP, neutral
detergent fiber (NDF), and IVTD. Economics of
producing these forages was compared to that
for perennial and annual peanut forage using
models of Hewitt (2006) and Prevatt (2008).

Statistical Analyses
The experimental design was a randomized
complete block. Data were analyzed as repeated
measures with PROC MIXED (SAS Inst. Inc.,
Cary, NC). The model included yr, forage
species, week after planting (WAP), block and
the interactions. Significance was declared at P
< 0.05.

Results and Discussion
Herbage Mass and Leaf-to-stem Ratio
There were no yr or yr x forage species
interactions therefore results shown are means
across yr. Figure 1 shows the herbage mass for
each legume through the growing season.
Pigeonpea reached the recommended harvest
stage at 14 WAP, whereas soybean and cowpea
reached their recommended harvest stages at 16
and 20 weeks per planting, respectively. At the
recommended maturity stage, soybean and
pigeonpea had greater herbage mass than
cowpea. Figure 2 shows that leaf-to-stem ratio
decreased with maturity after a slight initial
increase in all forages. From 10 to 14 WAP, the
leaf-to-stem ratio of cowpea was greater than
those of pigeonpea and soybean, which were
similar. Herbage mass and leaf-to-stem ratio
differences among the species are due to
morphological and physiological differences.
'Iron clay' cowpea is a viney, low growing plant
with large leaves and an indeterminate growth
habit; therefore, it continued to produce new
foliage after flowering and leaves did not
senesce as soon as the other species. The


soybean cultivar used in this experiment was late
maturing (VII), with upright, tall (1.5 to 2.0 m)
growth and the proportion of leaf declined
through maturity at R7 stage. Pigeonpea is a
tree-like legume that grows tall and has a woody
main stem, and its small leaves begin to senesce
at 9 WAP. Pigeonpea and soybean had greater
herbage mass than cowpea because of their
upright growth habit and thicker stems which
supported greater herbage mass.

Nutritive Value
The CP concentration of each forage decreased
through the growing season (Figure 3). Between
8 WAP and the respective recommended harvest
stages, cowpea had the greatest CP
concentration, whereas soybean had a greater CP
concentration than pigeonpea from 10 WAP to
the recommended harvest stage for pigeonpea.
Pigeonpea had a greater NDF concentration than
the other legumes between 10 and 14 WAP, and
soybean had a greater NDF concentration than
cowpea between 8 and 14 WAP. The IVTD of
annual legumes decreased with maturity in
pigeonpea and cowpea, but the rate and extent of
the decrease was greater in pigeonpea. From 8
to 14 WAP, cowpea had the greatest IVTD,
followed by soybean. Soybean and cowpea
have more potential as forages for ruminants
than pigeonpea. Cowpea is a promising energy
and protein supplement but the herbage mass is
relatively low. The greater herbage mass and
high energy and protein concentration of
soybean makes it ideal for producing large
quantities of quality hay or haylage. Pigeonpea
is only recommended for grazing cattle or
storage as hay or haylage if it is less than 8
WAP.
Economics
Establishment of perennial peanut is more
expensive than establishment of the other
legumes; however, the annual maintenance cost
of the seeded legumes is greater because they
are planted each yr (Table 1). Cowpea
produced the least herbage mass (Table 1) and
therefore had the least net present value after 20
yr (Table 2). Perennial peanut is the best long
term investment, but the other legumes will
produce earlier returns on the investment.


2009 Florida BeefReport



























































1Jamie Foster, Former Graduate Student; Adebola Adesogan, Associate Professor, UF/IFAS, Department
of Animal Sciences, Gainesville, Florida; and Jeffery Carter, Former Assistant Professor; Bob Myer,
Professor; Ann Blount, Professor, UF/IFAS, North Florida Research and Education Center, Marianna;
Florida Lynn Sollenberger, Professor, UF/IFAS, Agronomy Department.


2009 Florida BeefReport


Literature Cited
Hewitt, 2006. http://nfrec.ifas.ufl.edu/Hewitt/budgets.htm
Le Houerou, 2006. http://www.fao.org/ag/agP/AGPC/doc/gbase/data/Pf000150.HTM
Prevatt, 2008. http://www.ag.aubum.edu/agec//pubs/budgets/2008/forcrop08.php
Sheaffer et al. 2001. Agron. J. 93:99.
Twidwell et al. 2002. S. Dakota State Univ. Circular 8070.










Table 1. Costs of producing perennial peanut (cv. 'Florigraze'), annual peanut (cv. 'Florida MDR 98'), cowpea (cv.
'Iron clay'), pigeonpea (cv. 'GA-2'), and soybean (cv. 'Pioneer 97B52') forage, hay, or haylage production in 2006
Cost of Cost of
Seed or Seed or Initial Annual Herbage No. of hay Haylage
sprig cost, sprig establishment maintenance mass, tons bales/ baling5, baling6,
Forage $ rate/ ac cost', $/ac cost2, $/ac DM3/ac/yr ac/yr4 $/ac/yr $/ac/yr

Perennial 3.00/bu 80 bu 688 212 4.5 30 420 330
peanut

Annual 0.55/lb 18 lb 256 212 3.6 24 336 264
peanut

Cowpea 0.88/lb 50 kg 296 264 2.3 15 210 165

Pigeonpea 2.00/lb 50 kg 360 328 3.9 26 364 286

Soybean 0.88/kg 50 kg 296 264 3.8 25 350 275

'Includes seed, fertilizer (290 lb/ac 0-20-40 ratio of N:P205:K20), 1,600 lb/ac lime, herbicide, machinery, labor, and
estimated interest on monetary investment
2Includes seed for cowpea, pigeonpea and soybean, fertilizer (290 kg/ha 0-20-40 ratio of N:P205:K20), herbicide,
machinery, labor, and estimated interest on monetary investment, but not lime because it should be required every 2
to 3 yr
3Dry matter (DM)
4Estimated from small (300 lb) round bales utilized
5Estimated from $14.00 charge per bale for twine, machinery, and labor
6Estimated from $11.00 charge per bale for twine, plastic wrap, machinery, and labor
Equations from Hewitt, 2006 and Prevatt, 2008



Table 2. Net present value summary for perennial peanut (cv. 'Florigraze'), annual peanut (cv. 'Florida MDR 98'),
cowpea (cv. 'Iron clay'), pigeonpea (cv. 'GA-2'), and soybean (cv. 'Pioneer 97B52') forage, hay, or haylage production
over a 20-yr horizon

Hay production net Haylage production net
Forage present value', $/ac present value', $/ac
Perennial peanut 3,728 4,596
Annual peanut 3,292 4,068
Cowpea 576 1,064
Pigeonpea 2,664 3,520
Soybean 3,076 3,892
'Estimated rate of return after 20-yr using the value of income and expense today. The greater the number, the greater
the return on investment after 20-yr.
Expenses included 7% interest rate and $80 liming (1,600 kg/ha) in alternate yrs; profit included $37 value of 300 lb
round bale.


2009 Florida BeefReport











Figure 1. Changes in herbage mass (tons dry matter (DM)/ac) of cowpea, pigeonpea and soybean
abcMeans at each week after planting without a common superscript letter differ (P < 0.05).
Standard error of the mean = 0.42 tons DM/ac

-8- Pigeonpea
Soybean
4 ***** Cowpea


.... b c b


10 15
Weeks after planting


Figure 2. Leaf-to-stem ratio of cowpea, pigeonpea, and soybean
abcMeans at each week after planting without a common superscript letter differ (P < 0.05).
Standard error of the mean = 0.05

-e- Pigeonpea
1 Soybean
"***" Cowpea


I .L

I 1

0.8

S0.6

0.4

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Sb
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10 15
Weeks after planting


2009 Florida BeefReport












Figure 3. Whole plant crude protein (CP) and neutral detergent fiber (NDF) concentrations (dry matter
(DM) basis) and in vitro true DM digestibility (IVTD) of cowpea, pigeonpea, and soybean

abcMeans at each week after planting without a common superscript letter differ (P < 0.05).
Standard errors of the means for CP, NDF, and IVTD were 14, 18, and 17, respectively.


a
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Weeks after planting


a a
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10 15
Weeks after planting


ab .......

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c c **3
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10 15
Weeks after planting


2009 Florida BeefReport


b) 90
80

70
60
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Q
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30

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a) 30.0

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p 15.0

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Full Text

PAGE 1

Annual Legumes to Complement Warm Season Perennial Grass Forage Systems in North Florida Jamie Foster 1 Adegbola Adesogan Jeffrey Carter Lynn Sollenberger Robert Myer Ann Blount Summary This study determined the herbage mass, leafto stem ratio, and nutritive value of soybean [Glycine max (L.) Merr.], cowpea [Vigna unguiculata (L.) Walp.], and pigeonpea [Cajanus cajan (L.) Millsp.] grown in North Florida. Forages were grown in each of four blocks in three yr and harvested biweekly until the recommended maturity stage. Herbage mass of the forages increased through the growing season, and at the respective maturity stages soybean (3.8 tons dry matter (DM)/ac) and pigeonpea (3.9 tons DM/ac) had greater herbage mass than cowpea (2.3 tons DM/ac). Leafto -stem ratio decreased with maturity after a slight initial increase in all forages. At harvest, pigeonpea contained 12% crude protein (CP; DM basis) and 35% in vitro true DM digestibility (IVTD), soybean contained 18% CP and 73% IVTD, and cowpea contained 19% CP and 69% IVTD. Soybean and cowpea have potential to provide high quality forage to livestock in North Florida. Introduction In Florida and much of the Southern USA, bahiagrass [ Paspalum notatum Flgge] and bermudagrass [ Cynodon dactylon (L.) Pers.] are the main pasture forages. However, their availability for winter grazing is limited and their digestibility and CP concentration are often insufficient for growing and lactating cattle in midto -late fall. Warm-season legumes can provide the needed supplementary nutrients, and when stored as hay or haylage, they can be fed in the winter to supplement stored and stockpiled grasses. The increasing costs of fuel and fertilizer have made such legumes more attractive to producers and necessitated evaluation of their yield and nutritive value. The objective of this study was to compare the herbage mass, chemical composition, IVTD, and leafto -stem ratio of cowpea ( ), (cv. GA). Materials and Methods In each of three yr, cowpea, soybean, and pigeonpea were grown at the North Florida Research and Education Center in Marianna, FL. Each legume was grown on a replicated plot within each of four blocks. The field was prepared by plowing and fertilizing with P and K to soil test recommendation. Immediately prior to planting, seeds were inoculated with the appropriate rhizobia and drilled at 50 lb/ac and 6-in row spacing. Planting dates for yr one (2005) and two (2007) were 9 and 10 May, respectively. Duplicate forage samples were taken from each plot with mechanical clippers from a 0.2-m 2 area and harvested to a 2-in stubble height after This study indicated that cowpea and soybean are promising quality forages for hay and haylage production in North Florida

PAGE 2

plants reached approximately 11 in height. Sampling continued every 2 weeks until harvest at the following recommended maturity stages: pods began to turn yellow for cowpea (Twidwell et al., 2002), pod setting for pigeonpea (Le Hourou, 2006), and stage R6 (full size seed in pods at one of the four uppermost nodes and completely unrolled leaves) for soybean (Sheaffer et al., 2001). Leafto -stem ratio was measured on duplicate samples from each plot after removal of leaves at the node. Samples were ground and analyzed for CP, neutral detergent fiber (NDF), and IVTD. Economics of producing these forages was compared to that for perennial and annual peanut forage using models of Hewitt (2006) and Prevatt (2008). Statistical Analyses The experimental design was a randomized complete block. Data were analyzed as repeated measures with PROC MIXED (SAS Inst. Inc., Cary, NC). The model included yr, forage species, week after planting (WAP), block and the interactions. Significance was declared at P < 0.05. Results and Discussion Herbage Mass and Leafto -stem Ratio There were no yr or yr forage species interactions therefore results shown are means across yr. Figure 1 shows the herbage mass for each legume through the growing season. Pigeonpea reached the recommended harvest stage at 14 WAP, whereas soybean and cowpea reached their recommended harvest stages at 16 and 20 weeks per planting, respectively. At the recommended maturity stage, soybean and pigeonpea had greater herbage mass than cowpea. Figure 2 shows that leafto -stem ratio decreased with maturity after a slight initial increase in all forages. From 10 to 14 WAP, the leafto -stem ratio of cowpea was greater than those of pigeonpea and soybean, which were similar. Herbage mass and leafto -stem ratio differences among the species are due to morphological and physiological differences. with large leaves and an indeterminate growth habit; therefore, it continued to produce ne w foliage after flowering and leaves did not senesce as soon as the other species. The soybean cultivar used in this experiment was late maturing (VII), with upright, tall (1.5 to 2.0 m) growth and the proportion of leaf declined through maturity at R7 stage. Pigeonpea is a tree-like legume that grows tall and has a woody main stem, and its small leaves begin to senesce at 9 WAP. Pigeonpea and soybean had greater herbage mass than cowpea because of their upright growth habit and thicker stems which supported greater herbage mass. Nutritive Value The CP concentration of each forage decreased through the growing season (Figure 3). Between 8 WAP and the respective recommended harvest stages, cowpea had the greatest CP concentration, whereas soybean had a greater CP concentration than pigeonpea from 10 WAP to the recommended harvest stage for pigeonpea. Pigeonpea had a greater NDF concentration than the other legumes between 10 and 14 WAP, and soybean had a greater NDF concentration than cowpea between 8 and 14 WAP. The IVTD of annual legumes decreased with maturity in pigeonpea and cowpea, but the rate and extent of the decrease was greater in pigeonpea. From 8 to 14 WAP, cowpea had the greatest IVTD, followed by soybean. Soybean and cowpea have more potential as forages for ruminants than pigeonpea. Cowpea is a promising energy and protein supplement but the herbage mass is relatively low. The greater herbage mass and high energy and protein concentration of soybean makes it ideal for producing large quantities of quality hay or haylage. Pigeonpea is only recommended for grazing cattle or storage as hay or haylage if it is less than 8 WAP. Economics Establishment of perennial peanut is more expensive than establishment of the other legumes; however, the annual maintenance cost of the seeded legumes is greater because they are planted each yr (Table 1). Cowpea produced the least herbage mass (Table 1) and therefore had the least net present value after 20 yr (Table 2). Perennial peanut is the best long term investment, but the other legumes will produce earlier returns on the investment.

PAGE 3

Literature Cited Hewitt, 2006. http://nfrec.ifas.ufl.edu/Hewitt/budgets.htm Le Hourou, 2006. http://www.fao.org/ag/agP/AGPC/doc/ gbase/data/Pf000150.HTM Prevatt, 2008. http://www.ag.auburn.edu/agec//pubs/budgets/2008/forcrop08.php Sheaffer et al. 2001. Agron. J. 93:99. Twidwell et al. 2002. S. Dakota State Univ. Circular 8070. 1 Jamie Foster, Former Graduate Student; Adebola Adesogan, Associate Professor, UF/IFAS, Department of Animal Sciences, Gainesville, Florida; and Jeffery Carte r, Former Assistant Professor; Bob Myer, Professor; Ann Blount, Professor, UF/IFAS, North Florida Research and Education Center, Marianna; Florida Lynn Sollenberger, Professor, UF/IFAS, Agronomy Department.

PAGE 4

Jamie Foster Adegbola Adesogan Jeffrey Carter Lynn Sollenberger Robert Myer Ann Blount Table 1. in 2006 Forage Seed or sprig cost, $ Seed or sprig rate/ ac Initial establishment cost 1 $/ac Annual maintenance cost 2 $/ac Herbage mass, tons DM 3 /ac/yr No. of bales/ a c/yr 4 Cost of hay baling 5 $/ac/yr Cost of Haylage baling 6 $/ac/yr Perennial peanut 3.00/bu 80 bu 688 212 4.5 30 420 330 Annual peanut 0.55/lb 18 lb 256 212 3.6 24 336 264 Cowpea 0.88/lb 50 kg 296 264 2.3 15 210 165 Pigeonpea 2.00/lb 50 kg 360 328 3.9 26 364 286 Soybean 0.88/kg 50 kg 296 264 3.8 25 350 275 1 Includes seed, fertilizer (290 lb/ac 0 20 40 ratio of N:P 2 O 5 :K 2 O), 1,600 lb/ac lime, herbicide, machinery, labor, and estimated interest on monetary investment 2 Includes seed for cowpea, pigeonpea and soybean, fertilizer (290 kg/ha 0 20 40 ratio of N:P 2 O 5 :K 2 O), herbicide, m achinery, labor, and estimated interest on monetary investment, but not lime because it should be required every 2 to 3 yr 3 Dry matter (DM) 4 Estimated from small (300 lb) round bales utilized 5 Estimated from $14.00 charge per bale for twine, machinery, and labor 6 Estimated from $11.00 charge per bale for twine, plastic wrap, machinery, and labor Equations from Hewitt, 2006 and Prevatt, 2008 Table 2. over a 20 yr horizon Forage Ha y production net present value 1 $/ac Haylage production net present value 1 $/ac Perennial peanut 3,728 4,596 Annual peanut 3,292 4,068 Cowpea 576 1,064 Pigeonpea 2,664 3,520 Soybean 3,076 3,892 1 Estimated rate of return after 20 yr using the value of income and expense today. The greater the number, the greater the return on investment after 20 yr. Expenses included 7% interest rate and $80 liming (1,600 kg/ha) in alternate yrs; profit included $37 value of 300 lb round bale.

PAGE 5

Figure 1. Changes in herbage mass (tons dry matter (DM)/ac) of cowpea, pigeonpea and soybean abc Means at each week after planting without a common superscript letter differ ( P < 0.05). Standard error of the mean = 0.42 tons DM/ac Fi gure 2. Leaf to stem ratio of cowpea, pigeonpea, and soybean abc Means at each week after planting without a common superscript letter differ ( P < 0.05). Standard error of the mean = 0.05

PAGE 6

Figure 3 Whole plant crude protein (CP) and neutral detergent fiber (NDF) concentrations (dry matter (DM) basis) and in vitro true DM digestibility (IVTD) of cowpea, pigeonpea, and soybean abc Means at each week after planting without a common superscript letter differ ( P < 0.05). Standard errors of the means for CP, NDF, and IVTD were 14, 18, and 17, respectively.