MAR 2 5 1993
D.L Wright, I.D. Teare and R.L. Stanlejn iversOity, f Florida
The greatest economic value from a corn crop is obtained when
it can be used as silage rather than for grain only. The ojectives
were to study tropical corn silage yield and quality in relation to
starter fertilizer, planting date, corn hybrid, and fall armyworm
stress. This study was conducted in the field at Quincy and Jay
Florida during 1991 and 1992. Results have shown the interaction
of tropical corn silage to starter fertilizer and hybrids. Pioneer
X304 C was a positive changer, DeKalb DK 9101 was a no-changer, and
Pioneer 3099 and Cargill X701TR were negative changers. In 1992,
fall armyworm migrated to Quincy one month earlier than usual.
Some hybrids were not as tolerant to fall armyworm as others. Late
planted tropical corn resulted in high yields of corn silage. Feed
quality (%CP and IVOMD) of tropical corn grain and silage varied in
relation to planting date and hybrid.
North Fla. Res. & Educ. Ctr., Quincy FL 32351.
Florida, Fla. Exp. Stn Res. Rep. No. NF 93-9
Grain and Silage Evaluation
of Tropical Corn
in a Minimum Tillage System
The greatest economic value from a corn crop is obtained when
it can be used as silage rather than only for grain. Recently in
the "Sunbelt" of this area, there has been a surging growth of
population accompanied by increased sales of milk and milk products
and significant growth in dairy farming. Increased dairying has
been most notable in Florida, Georgia and Texas with a concommitant
increase in the demand for corn silage of highly digestible dry
Most of the high yielding (temperate) corn hybrids in the U.S.
produce silages in which nearly 50 % or more of the DM is grain.
Feeding these silages, high in non-structural carbohydrates
(starch), to ruminants such as production stressed cows can cause
severe problems in the digestive tract unless the total is
.formulated to compensate for the high proportion of starch.
If corn silages with lower starch contents were used (no more
than 40 % of the DM as grain, ie, tropical corn) it would be easier
to maintain lactating cows with normal heathly digestive systems.
Thus, corn silage containing lower proportions of grain would be
more desirable for dairy farmers provided high digestibility could
be maintained or increased without any reduction of silage intake
by cows (Johnson, 1991).
Legislated disposal of dairy waste and the recycling of waste
as fertilizer for the year-round production of dairy forage
(sequential-cropping) may become the driving force for the use of
tropical corn or pearl millet (Teare et al., 1991) during the hot
summer months in the southeast.
Struink (1989) showed that when harvested at similar
maturities, the digestibilities within corn genotypes were fairly
constant when grown in a wide range of environments. However,
other plant charactistics such as yielding ability were strongly
influenced by differences in climatic conditions and associated
Tropical corn hybrids are most useful where prevailing
environmental conditions usually are unfavorable for adapted
domestic temperate cultivars. Tropical hybrids have been selected
for their adaptation for short days, high temperatures and high
humidity; moderate yields at moderate fertility levels; and disease
and insect resistance. In contrast, temperate hybrids have been
selected for maximization of yields (high fertility rates and
adequate soil moisture), early planting (cooler weather), and
northern latitudes (longer days and lower humidity). Thus, we have
two corn hybrid groups that are used in different environments,
depending on the planting date and degrees latitude. All tropical
corn hybrids may not perform well under Southeastern conditions.
Pioneer X304C is tolerant to fall armyworm and southern rust
(Puccinia polysora) invasion, but some tropical hybrids have been
noted to have no more tolerance than temperate hybrids. Therefore,
tropical corn hybrids must be evaluated for each area/use before
reliable recommendations can be made.
Tropical corn hybrids can be no-till planted and multiple-
cropped after winter grains, vegetables, or early-planted,
temperate corn harvested for silage (Wright et al., 1990). Early
May planting of tropical corn allows the escape of heavy infesta-
tion of fall armyworm [Spodoptera fruciperda (J. E. Smith)] that
can devastate tropical corn planted after 10 June (Teare et al.,
Much of the "Sunbelt" of the southeastern United States is
suitable for sequential-cropping because silage crops do not
require full maturity. It is possible to produce on the same land
in the southeast: one winter crop of cereal grains, followed by an
early spring temperate corn crop, then a mid-summer planted
tropical corn crop.
The objectives of were to: 1) study tropical corn silage
yields in relation to starter fertilizer and no-starter, 2) observe
tropical corn silage yield damage in relation to planting date and
fall armyworm stress, 3) measure grain and silage quality in
relation to grain and silage yields, planting, and corn hybrids.
MATERIALS AND METHODS
All tropical corn studies reported herein were conducted under
a medium-energy-input system defined by Teare et al. (1993) as a
no-till planting system following wheat harvest, fertilized with
<134 kg N ha'' and grown under natural-rainfall conditions. The
experiments were conducted at two locations: 1) the North Florida
Research and Education Center on a Norfolk sandy loam soil (fine-
loamy, siliceous, thermic, Typic Kandiudult) and 2) The
Agricultural Research Center, Jay, FL on a Orangeburg sandy loam.
The plot sizes were 7.6 m long by 6 m wide (eight rows). Row
spacing was 0.76 m. The previous crop in each experiment was Fla
303 winter wheat, harvested in mid-May. Tropical corn hybrids were
planted no-till into the small grain stubble with a Brown-Harden
Ro-Til planter' at a population density of 20,000 plants ha1.
The experimental design of was a randomized complete block with
four replications. Grain and sorghum yields on fourteen tropical
corn hybrids. Planting, silage harvest and grain harvest were 19
May, 18 June, and 5 Oct, respectively.
The tropical corn late planted, June vs July comparison was
planted on 17 June and 6 July at Jay, FL, 1992 and was harvested
'Brown Co., Ozark, AL 32630.
on. Both planting dates were fertilized with 134 kg N ha'1 and a
population density of 20,000 plants ha'1. The rows were 7.6 m long
by 3 m (four rows) with 0.76 m between rows. The previous crop was
winter wheat harvested in late May. The experimental design was
split plot with four replications. Whole plots were the planting
dates. The sub-plots were 14 tropical hybrids (Table 2).
Tropical corn grain yield and % grain crude protein (DM) comparison
was conducted as a measure of grain quality of 27 tropical corn
hybrids in 1991. Planting date was 1 July and harvest date was 31
Oct. The experiment was a completely randomized block with 4
Fourteen tropical corn hybrids were compared in a starter vs
no-starter silage yield experiment. It was a complete randomized
block experiment with four replications. It was planted on 18
June? and harvested for silage on 16 Sept. Interactions are
illustrated according to the technique of Teare and Wright (1990).
Results and Discussion
The interaction of temperate corn hybrid grain yields in
relation to small amounts of starter fertilizer application at time
of planting was described by Teare et al. in 1990. This explained
the highly variable temperate corn yield results from starter
fertilizer experiments reported throughout the United States. It
also provided another management tool for farmers to consider in
their selection of seed corn for optimization of yield. In 1992 a
starter fertilizer experiment was conducted on tropical corn
hybrids for the first time in relation to silage yield. Silage
yields of 14 tropical hybrids are shown in relation to starter and
no-starter application at planting (Table 1). The interactions are
shown in figure 1. Pioneer X304C showed the greatest range as the
"positive changer" and Pioneer 3099 and Cargill X701TR the greatest
ranges as the "negative changers". DeKalb DK 9101 showed the least
change as a "non-changer".
Table 1. Silage yield of 14 tropical corn hybrids in relation to
starter fertilizer, Quincy, Florida, 1992. Planting and
silage harvest dates are 18 June and 16 September,
Hybrid at planting (35% DM)
Cargill X701TR 12.6 A
Pioneer 3099 11.3 AB
Pioneer X304C + 11.2 AB
Pioneer 3069 + 11.1 ABC
Cargill X701TR + 10.9 ABC
Pioneer 3072 + 10.8 BCD
DeKalb DK X9052 10.8 BCD
Pioneer 3069 10.5 BCDE
Pioneer 3072 10.5 BCDE
DeKalb DK X9152 10.4 BCDE
Dekalb DK X9052 + 10.3 BCDE
Pioneer X304C -9.9 BCDEF
Dekalb DK X9152 + 9.7 BCDEF
Pioneer 3099 + 9.7 BCDEF
Pioneer 4098 + 9.5 CDEFG
Pioneer 3098 -9.2 DEFGH
Dekalb DK XL510 8.9 EFGH
Dekalb DK XL510 + 8.5 FGH
DeKalb DK XL678C 8.0 GHI
DeKalb DK XL678C + 7.6 HI
DeKalb DK XL520 + 7.5 HI
DeKalb DK XL520 -6.8 I
Cargill C955 -4.1 J
DeKalb DK 9101 + 3.9 J
DeKalb DK 9101 -3.8 J
Cargill C955 + 3.6 J
Cargill 9197 -3.0 J
Cargill 9197 + 2.7 J
"Silage yield in column followed by the same letter are not significantly
different at the 5% level of probability.
Table 2. Grain and silage yield' of 14 tropical corn hybrids,
Quincy, FL, 1992. Planting, silage and grain harvest
dates 19 May, 18 June, 5 Oct, respectively.
Grain yield2 Silage yield3
Hybrid (bu/A) (ton/A)
Pioneer 3099 136.9 A 10.5 B
Pioneer 3069 124.5 AB 10.8 AB
Pioneer 3072 119.9 ABC 10.6 AB
Pioneer 3098 106.7 BCD 9.3 CD
DeKalb XL678C 105.2 BCD 7.8 EF
Pioneer X304C 99.4 CD 10.5 B
Cargill C955 96.8 D 3.9 G
DeKalb XL510 96.7 D 8.7 DE
Cargill X701TR 93.9 D 11.8 A
DeKalb X9052 93.2 D 10.6 B
DeKalb 9101 91.9 D 3.8 G
DeKalb X9152 90.7 D 10.0 BC
Cargill 9197 88.4 D 2.8 G
DeKalb XL520 87.2 D 7.1 F
1 Yield in columns
at the 5 % level
2 Corrected to 15.5
3 Corrected to 35 %
4 Comparison for 35
followed by the same letter are not significantly different
Early (May) planting of tropical corn has been shown to be an
escape management tool for evading fall armyworm damage (Teare et
al., 1990 and 1991. Planting date studies in 1992 show unique
weather influences not observed in the previous eight years of
tropical corn research. Weather during the winter of 1992 was very
mild and spring temperatures and rainfall were higher than normal.
As a result fall armyworm migrations north from Puerto Rico and
southern Florida were about a month earlier than usual. This was
the first time we've seen heavy fall armyworm damage to grain yield
in May planted tropical corn. Grain and silage yields of 14
tropical corn hybrids are shown for the 19 May 1992 plant in Quincy
in Table 2. Grain yields were good, but some silage yields were
low showing the effect of fall armyworms on some tropical hybrids
whose tolerance to fall armyworm must be low. The low silage
yielding hybrids for the May planting was what we'd expect with
June planting dates.
Table 3 shows the grain yields of two late plantings of the
same tropical corn hybrids at Jay. The high grain yields for the
mid-June and Early-July planting dates (the highest in our nine
years of tropical corn research) indicated that the fall armyworm
migrated north earlier than usual and allowed the tropical corn
hybrids to express their grain yield potentials late in the growing
season without heavy insect damage. Early July planted tropical
corn grain yields for 27 hybrids in 1991 (Table 4) are shown as the
more "normal" low grain yields from later migrating fall armyworms
to compare with Table 3.
Table 3. Grain yield' of late planted2 tropical corn hybrid trials
at two planting dates (17 June and 6 July) at Jay, FL,
Hybrid Mid-June Early July
Pioneer 3072 114.1 115.4
Pioneer 3099 98.5 109.5
Pioneer 3069 95.3 100.5
DeKalb X9152 77.1 89.5
Cargill X701TR 78.4 81.0
Pioneer 3098 80.4 79.1
DeKalb X9052 62.9 77.1
Pioneer X304C 50.6 70.7
DeKalb XL678C 50.6 60.9
DeKalb XL510 38.2 42.8
DeKalb XL520 32.4 35.7
Cargill C955 18.1 16.9
DeKalb 9101 14.9 13.0
Cargill 9197 12.3 11.0
Means 59.0 64.2
LSDo0 18.8 16.9
SCorrect to 15.5% moisture.
2 Rainfall Distribution (Inches)
Table 4. Tropical corn grain yield and percentage grain crude
protein (DM) for 27 hybrids at Quincy, Florida, 1991.
Planting and harvest dates were 1 July and 31 October,
yield % CP
Hybrid (Bu/A) (DM)
Cargill Semiden 5
iGrain yield and % CP in columns followed by the same
significantly at the 5% level of probability.
letter are not
Grain and silage feeding quality for ruminant animals is
estimated by measurements of percent crude protein on a dry matter
basis and in vitro organic matter digestiblity (IVOMD) (Moore and
Mott, 1974). Table 4 also shows the percent crude protein of 27
tropical corn hybrids grown at Quincy in 1991 along with
corresponding grain yields.
In vitro organic digestibility and silage yields are shown in
Table 5 for five tropical corn hybrids at Quincy in 1991.
Table 5. In vitro organic matter digestibility and
silage yields of five tropical corn hybrids, Quincy,
1991. Planting date 1.
Hybrid (Ton/A) (%)
Pioneer 3098 9.2 A 38.8 A
Pioneer 3214 7.4 A 38.7 A
Pioneer X304C 8.8 AB 38.6 A
Pioneer 3210 6.0 B 37.2 A
Pioneer 6875 6.4 B 35.5 A
n o N H C%
c < u u u
0 CO LA N LA 0
o- g H -c
0 a)-I 44
H E-4 ,- H -4 ,- 0-
-. '1 4
> a ( *
O N (D
%D 0 m O O o- -
0)i 0 m o
O M **
u >, a 4 V I O
0 "P .
U v 04 C L n '
4o > t rO 0 Nj
S1 rE- N 4 4 -
.-* r>l 1
U0 0 0 00
H Co X C
m o r 0 % r
H 0 N
0 0 H
a1 CO 0 H N C 0A CO Mc 0
4.) I- 0i
O VO c> V
.0 0 X P
p0 0 >
CO) 0 N^ H a t Co CO
C C w 0
0 0 0 4
4-4 Q) >
0 XQ H H N0c E g
El 4 H 0 3 NttA
.0 CI d) <; g 0
rN rt N 14 0
E-l ~ ~ H
In vitro organic matter digestibility and silage yield are also
shown for another study that compared two tropical corn hybrids and
one high yielding corn temperate corn at four planting dates at
Quincy, 1991. The May planting was in a very vulnerable vegetative
stage when the fall armyworm invaded in June which resulted in the
decision to harvest early and reduced the silage yields of the May
planted silage crop of all hybrids. In vitro organic digestable
organic matter was also reduced because of the reduced leaves and
Our thanks to E. Brown, Agricultural Technician IV and B.T. Kidd,
Biological Scientist II; North Fla. Res. and Educ. Ctr. Univ of
Fla., Quincy FL; for plot preparation, and management, data
collection, computer processing, and data illustration.
Johnson, J.C., Jr. 1991. Tropical corn for silage. pp. 5-10. In
I.D. Teare and E. Brown (eds.). "Proceedings Southern
Regional Tropical Corn Symposium" PPI/FAR Tech. Bull. 1991-3.
Potash & Phosphate Inst./Foundation for Agron. Res. and Univ.
of Fla. May 27, 28. Quincy FL.
Lilly, D.P., D.L. Wright, I.D. Teare, R.N. Gallaher, and R.L.
Stanley. 1993. Tropical corn vs. planting dates, nitrogen,
and water. Soil Crop Sci. Soc. Fla. 50:In Press.
Moore, J.E. and G.O. Mott. 1974. Recovery of residual organic
matter from in vitro digestion of forages. J. Dairy Sci.
Rhoads, F.M., D.L. Wright, and I.D. Teare. 1993. Starter
fertilizer responsive versus non-responsive corn hybrids.
Agron J. 86:In Process.
Struik, P.C. 1982. Production pattern, chemical composition and
digestibility of forage maize (Zea mays L.). Agricultural
University, Wageningen, Vagroep Landbouwplantenteelt en
Graslandkunde, Mededling nr. 64,28 p.
Teare, I.D., J.C. Johnson, and F.M. Rhoads. 1991. Tropical corn
and it's relation to dairy waste disposal. pp. 11-14. In I.D.
Teare and E. Brown (ed.). "Proceedings Southern Regional
Tropical Corn Symposium" PPI/FAR Tech. Bull. 1991-3. Potash
& Phosphate Inst./Foundation for Agron. Res. and Univ. of Fla.
May 27, 28. Quincy FL.
Teare, I.D., D.L. Wright. 1991. The environment and tropical
corn. pp. 37-41. In I.D. Teare and E. Brown (ed.).
"Proceedings Southern Regional Tropical Corn Symposium"
PPI/FAR Tech. Bull. 1991-3. Potash & Phosphate Inst./
Foundation for Agron. Res. and Univ. of Fla. May 27, 28.
Teare, I.D., D.L. Wright, R.K. Sprenkel, R.L. Stanley, and D.P.
Lilly. 1991. Tropical corn hybrids in a no-tillage system.
pp. 75-80. In T. C. Keisling (ed.) Proc. 1991 Southern Cons.
Tillage Conf. Ark. Expt. Stn. Rep. 91-1, Fayetteville, AR,
Univ. of Arkansas.
Teare, I.D., D.L. Wright, and R.K. Sprenkel. 1990. Early planting
reduces fall armyworm problems in no-till tropical corn. pp.
38-41. In J.M. Mueller (ed.) Proc. 1990 Southern Cons.Tillage
Conf. SB 90-1, Raleigh NC, North Carolina State Univ.
Teare, I. D., and D. L. Wright. 1990. Corn hybrid-starter
interaction for yield and lodging. Crop Sci. 30:1298-1303.
Teare, I.D., D.L. Wright, and D.J. Zimet. 1989. No-Till research
with tropical corn in a doublecrop system. pp. 43-45. In
I.D. Teare (ed.) 1989 Southern Conservation Tillage
Conference, SB 89-1, Tallahassee, Florida.
Wright, D.L., I.D. Teare, and R.N. Gallaher. 1991. Corn silage
production in north Florida. pp. 15-20. In I.D. Teare and E.
Brown (ed.). "Proceedings Southern Regional Tropical Corn
Symposium" PPI/FAR Tech. Bull. 1991-3. Potash & Phosphate
Inst./ Foundation for Agron. Res. and Univ. of Fla. May 27,
28. Quincy FL.
Wright, D.L., R.N. Gallaher, and I.D. Teare. 1991. Tropical corn
as a grain crop. pp. 28-30. In I.D. Teare and E. Brown
(ed.). "Proceedings Southern Regional Tropical Corn
Symposium" PPI/FAR Tech. Bull. 1991-3. Potash & Phosphate
Inst./Foundation for Agron. Res. and Univ. of Fla. May 27,
28. Quincy FL.
Wright, D.L., D.P. Lilly, and I.D. Teare. 1990. Planting tropical
corn in minimum tillage systems. pp. 81-83. In J.M. Mueller
(ed.). Proc. 1990 Southern Cons. Tillage Conf. NCSU SB
90-1, Raleigh NC, North Carolina State Univ.
Wright, D.L. 1989. Starter fertilizer placement in no-till corn.
p.27-29. In I.D. Teare (ed.) 1989 Southern Conservation
Tillage Conference, Tallahassee, FL. 12-13 July 1989. SB 89-
1. Univ. of Fla., North Fla. Res. and Educ. Ctr., Quincy FL.
Wright, D.L., I.D. Teare, and B.T, Kidd. 1988. Ontogeny of maize
in relation to sequential cropping. Trop. Agric. (Trinidad)
Wright, D.L., and F.M. Rhoads. 1980. Management practices for 300
bushel corn. Fla. Coop. Ext. Serv., Agron Facts 108:1-7.