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Soybean Agronomics
Eric P. Prostko
Department of Soil & Crop Science
The University of Georgia
Soybean Production In Georgia – Acres Planted
0
500
1000
1500
2000
2500
3000
Year
Acr
es (X
100
0) .
Source: NASSSource: NASS
430
Soybean Production In Georgia – Yield
0
5
10
15
20
25
30
35
Year
Bu/A
.
Source: NASSSource: NASS2000-2008 = 27.562000-2008 = 27.561990-1999 = 23.201990-1999 = 23.201980-1989 = 21.401980-1989 = 21.40
Soybean Production In Georgia – Average Price
0
2
4
6
8
10
12
14
Year
$/B
u .
Source: NASSSource: NASS2000-2007 = 6.462000-2007 = 6.461990-1999 = 5.891990-1999 = 5.891980-1989 = 6.081980-1989 = 6.08
General Production Practices - I
• Crop rotation– Soybeans or other legumes once every 2 years
– CBR (peanuts) = Red crown rot (soybeans)
• Soil Fertility Issues– pH = 6.0
– Fertilize according to soil test results
– 40 bu/A soybeans will use 38 lbs/A P2O5 and 144 lbs/A K2O
– Use inoculant if soybeans have not been planted in last 3 years
• Soybeans = Bradyrhizobium japonicum
General Production Practices - II
• In-row sub-soiling in Coastal Plain region
• Planting Date– Optimum: May 10-June 10
– Late: June 11-June 30
– Avoid planting Group V after June 15
• Row Spacing– 15-36”
Row Spacing Effects on Soybean Yield In Georgia
• Carter and Boerma, 1979 (Athens, GA)
– 38” to 19” = 11% yield increase
• Boerma and Ashley, 1982 (Plains, GA)
– 36” to 20” = 17% yield increase
• Ethredge et al., 1989 (Plains, GA)
– 30” to 20” = 8% yield increase
– 30” to 10” = 11% yield increase
– 20” to 10” = 3% yield increase
• Woodruff, 2007-2008 (Camilla, GA)
– 36” to 24” = 8% yield increase
Washington County, GA (2008)
What about twin row soybeans?
• No Georgia data available.
• LSU trials indicated that twin rows outyielded single rows by 9%.
• MSU trials indicated that twin rows outyielded single rows by 10%.
• In Texas, twin rows outyielded single rows by 11%
• Will twin rows produce higher yields than narrow single rows??
General Production Practices - III
• Seeding Rate– May-Early June – 145,000 seed/Acre
• 36” rows = 10 seed/ft• 15” rows = 4 seed/ft
– Late June – 160,000 seed/A• 36” rows = 11 seed/ft• 15” rows = 4.6 seed/ft
• Planting Depth– 1”-1.25” deep
• UGA Recommended Varieties
What Group should you plant?
• UGA OVT Results
• 2001-2007 (7 years)
• Planted in early May
• Irrigated
• Six locations– Athens, Calhoun, Griffin,
Midville, Plains, Tifton
51.2 50.3 49.8
0
15
30
45
60
V VI VII,VIII
Maturity Group
Bu/A
.
Planting Early and Late Maturing Varieties Can Spread Drought Risks and Optimum Harvest Time
2008 UGA OVT ResultsGroup V – May PlantingTop 5 Yielding Varieties
Tifton Plains Midville Griffin Athens Calhoun
RT5951N RT5930N P95Y20 Progeny
5650RR
AGS
568RR
RT5760N
AG5905 Progeny 5650RR
RT5160N RT5760N Progeny
5650RR
Progeny
5650RR
P95Y20
Progeny 5706RR
Progeny 5622RR
AG5905 RT5960 Progeny
5622RR
UGA G03-1668RR
Progeny
5650RR
Dynagro
33X55
RT5930N AGS
568RR
UAK R0-976
RT5930N
UAK R0-976
UGA G03-1668RR
Progeny
5650RR
Progeny
5622RR
USG 7582nRR
RT5540N
2008 UGA OVT ResultsGroup VI – May PlantingTop 5 Yielding Varieties
Tifton Plains Midville Griffin Athens Calhoun
UAK R01-327
RT6207RR AG6702 RC 6298 RC 6298 UAK R03-1232
Musen AG6301 UAK R31-1134
V61N9RR UAK R01-327
UAK R31-1134
UAK R31-1134
USG 7635nRR
UAK R03-1232
AG6301
UAK R01-327
RT6988N DKB64-51
USG 7635nRR
USG 76S17
RT6600N NKS61-Q2 DKB64-51 AGS
606RR
USG 620nRR
RC 6298 AGS
606RR
UAK R03-1232
AG6702 USG 76S17
2008 UGA OVT ResultsGroup VII/VIII – May PlantingTop 5 Yielding Varieties
Tifton Plains Midville Griffin Athens Calhoun
V76N9RR V72N7RR UGA G00-3209
(Woodruff)
- UGA G00-3209
(Woodruff)
-
AG7502 USG 77U28
UGA G04-2414RR
- UGA G03-1187RR
-
UGA G04-1618RR
NKS78-G6 AG7501 - UGA G04-1618RR
-
UGA G00-3209
(Woodruff)
UGA G04-1618RR
USG 7732nRR
- USG 77S27
-
UGA G04-2215RR
Progeny
7208RR
RT 7355N - NKS78-G6 -
General Production Practices - IV
• Control Weeds
• Control Insects– Boron (0.25-0.5 lb/A) + Dimilin (2-4 oz/A) at R2-R3 stage –
Coastal Plain Region
• Control Soybean Rust if needed
R2
R3
Strobi Fungicides will cause green stem/leaf phenomenon
QuadrisQuadris DomarkDomark
Early Soybean Production Systems
• Planting Date: April 30-May 10• Harvest Date: Mid-September• MG IV or early V varieties (indeterminate)
– Pioneer 94M80 (RR), Southern States RT4808N (RR/STS), Southern States RT 5160N (RR)
• 15-30” row spacing• Increase seeding rates by 10-20%• Concerns
– stink bugs at early pod-fill (July)
– seed quality/shatter at maturity (timely harvest)– August/September hurricanes
2008 Early System Soybean Trial – Sunbelt Ag Expo
• Planting date: April 25• Seeding Rate: 175,000/A
– 6/row foot
• Row Spacing: 18”• Plot Size: 0.365-0.874 A• 3 replications• Fertility: 2 tons/A chicken litter• Irrigated• Fungicides: Headline (2x)• Insecticides:
– Boron + Dimilin– Stinkbugs
• Harvest Date: September 10• Trial conducted by Dr. John Woodruff
78 75 77
0
16
32
48
64
80
SSRT4808
P 94Y80 SSRT5160
Variety
Bu/A
.
P = 0.6597P = 0.6597CV = 4.17CV = 4.17
Soybean Irrigation
• Soybeans will produce ~ 2 bu/A for every 1” of water use.– 40-50 bu/A = 20-25” water
• Water Use by Stage (in/day)– Germination/Seedling = 0.05-0.01”– Vegetative = 0.10-0.20”– Flower to Pod Fill = 0.25-0.35”– Maturity to Harvest = 0.05-0.20”
• When to stop?– Pod-fill (R6)– 50+% of pods– green seed touching in pod
2007-2008 Soybean Irrigation Study
• Stripling Irrigation Research Park (Camilla)
• Varieties (2)– AGS 568– AGS 758
• Row Spacing (2)– 24” or 36 “
• Irrigation (4) (KanSched)– None (except emergence)– 60% irrigation all season– 120% irrigation all season– 60% irrigation during vegetative
growth, 120% irrigation during reproductive growth
2007-2008 Soybean Irrigation Study - Results
• No interaction between year, variety, row spacing, irrigation
• AGS 568 = AGS 758– 65.2/63.6 Bu/A
• 24” > 36” (8%)– 66.9 vs. 62.0 Bu/A
• Irrigation > dryland by 12.5% but no differences in yield between schedules
Irrigation vs DrylandStripling (2007-08) - Yield
5967 66 66
0
15
30
45
60
75
Dryland 60% 120% 60/120%
System
Bu/
A .
bbaa aa aa
Averaged over 2 years, 2 varieties, and 2 row spacings.Averaged over 2 years, 2 varieties, and 2 row spacings.
Irrigation vs DrylandStripling (2007-08) – Cost/Bu
6.647.73 7.92 7.88
0
2
4
6
8
10
Dryland 60% 120% 60/120%
System
$/B
u .
Averaged over 2 years, 2 varieties, and 2 row spacingsAveraged over 2 years, 2 varieties, and 2 row spacingsVariable + Fixed CostsVariable + Fixed Costs
Irrigation vs DrylandStripling (2007-08) – Net Return
139.24
85.0971.28 73.92
0
25
50
75
100
125
150
Dryland 60% 120% 60/120%
System
Net
Ret
urn
($/A
) .
Averaged over 2 years, 2 varieties, and 2 row spacingsAveraged over 2 years, 2 varieties, and 2 row spacings$9.00/Bu$9.00/Bu
Stripling Irrigation Research ParkRainfall 2007-2008
0
3
6
9
12
15
May June July Aug Sept Oct
Month
In .
Average 2007 2008
Source: Georgia Automated Environmental Monitoring Network
2009 Soybean Production Guide – Minor Editions
• 2008 UGA OVT Results (pages 109-128)
• MG VI– JGL EXP862 = Croplan Genetics RC 6298
• MG VII & VIII– Pioneer 95Y11 = Pioneer 98Y11
UGA Soybean Web-Pagehttp://www.gasoybeans.uga.edu