Soybean Agronomics Eric P. Prostko Department of Soil & Crop Science The University of Georgia

Soybean Production In Georgia – Acres Planted Source: NASS 430

Soybean Production In Georgia – Yield Source: NASS = = = 21.40

Soybean Production In Georgia – Average Price Source: NASS = = = 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 P 2 O 5 and 144 lbs/A K 2 O –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, (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 (7 years) Planted in early May Irrigated Six locations –Athens, Calhoun, Griffin, Midville, Plains, Tifton

Planting Early and Late Maturing Varieties Can Spread Drought Risks and Optimum Harvest Time

2008 UGA OVT Results Group V – May Planting Top 5 Yielding Varieties TiftonPlainsMidvilleGriffinAthensCalhoun RT5951NRT5930NP95Y20Progeny 5650RR AGS 568RR RT5760N AG5905Progeny 5650RR RT5160NRT5760NProgeny 5650RR Progeny 5650RR P95Y20 Progeny 5706RR Progeny 5622RR AG5905RT5960Progeny 5622RR UGA G RR Progeny 5650RR Dynagro 33X55 RT5930NAGS 568RR UAK R RT5930N UAK R UGA G RR Progeny 5650RR Progeny 5622RR USG 7582nRR RT5540N

2008 UGA OVT Results Group VI – May Planting Top 5 Yielding Varieties TiftonPlainsMidvilleGriffinAthensCalhoun UAK R RT6207RRAG6702RC 6298 UAK R MusenAG6301UAK R V61N9RRUAK R UAK R USG 7635nRR UAK R AG6301 UAK R RT6988NDKB64-51 USG 7635nRR USG 76S17 RT6600NNKS61-Q2DKB64-51AGS 606RR USG 620nRR RC 6298AGS 606RR UAK R AG6702USG 76S17

2008 UGA OVT Results Group VII/VIII – May Planting Top 5 Yielding Varieties TiftonPlainsMidvilleGriffinAthensCalhoun V76N9RRV72N7RRUGA G (Woodruff) -UGA G (Woodruff) - AG7502USG 77U28 UGA G RR -UGA G RR - UGA G RR NKS78-G6AG7501-UGA G RR - UGA G (Woodruff) UGA G RR USG 7732nRR -USG 77S27 - UGA G RR Progeny 7208RR RT 7355N-NKS78-G6-

General Production Practices - IV Control Weeds Control Insects –Boron ( 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 phenomenonQuadrisDomark

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: 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 P = CV = 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 = ” –Vegetative = ” –Flower to Pod Fill = ” –Maturity to Harvest = ” When to stop? –Pod-fill (R6) –50+% of pods –green seed touching in pod

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

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 Bu/A Irrigation > dryland by 12.5% but no differences in yield between schedules

Irrigation vs Dryland Stripling ( ) - Yieldb a aa Averaged over 2 years, 2 varieties, and 2 row spacings.

Irrigation vs Dryland Stripling ( ) – Cost/Bu Averaged over 2 years, 2 varieties, and 2 row spacings Variable + Fixed Costs

Irrigation vs Dryland Stripling ( ) – Net Return Averaged over 2 years, 2 varieties, and 2 row spacings $9.00/Bu

Stripling Irrigation Research Park Rainfall Source: Georgia Automated Environmental Monitoring Network

2009 Soybean Production Guide – Minor Editions 2008 UGA OVT Results (pages ) MG VI –JGL EXP862 = Croplan Genetics RC 6298 MG VII & VIII –Pioneer 95Y11 = Pioneer 98Y11

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