Location: Crop Genetics Research
Project Number: 6066-21220-016-028-A
Project Type: Cooperative Agreement
Start Date: Sep 20, 2025
End Date: Sep 19, 2027
Objective:
1. To evaluate agronomic characteristics, soybean productivity, and seed quality (seed composition and seed damage) under a range of soybean planting dates.
2. To determine nutrient recovery and cycling by cover crops with varied planting dates.
Approach:
The Early Soybean Production System (ESPS) involves planting in early spring to avoid the hot dry conditions that occur in late summer. ESPS resulted in higher seed yield, however, changing from traditional Midsouth soybean production systems where long season soybean cultivars were grown, to the ESPS which utilized earlier cultivars and exposed the soybean crop to late summer heat and humidity. Harvesting in late summer when temperatures and humidity are high often results in lower quality seeds with poor seed germination, disease infection, and mechanical damage. This makes the seed unsuitable as a seed source for planting and prone to price discounting when sold as grain. To avoid poor yield and quality and reduce seed damage, choosing the right planting date for soybeans is essential to help improve producer and farmer profitably.
Objective 1 evaluates agronomic characteristics, soybean productivity, and seed quality (seed composition and seed damage) under a range of soybean planting dates. A maturity group 4 soybean cultivar commonly planted in this region will be evaluated. The selected cultivar will be planted in replicated plots, either the more common wide rows or narrow rows. They will also be seeded at three seeding rates and three seed placement depths at the optimal planting date (around April 17th) as well as eight and twelve weeks before the optimal planting date.
Emergence date will be collected along with stand counts collected 15 and 30 days after emergence. Plant height and biomass ratings will be collected pre-flower and at full maturity. At harvest, yield will be measured for each plot. Soybean seed composition (seed protein, oil, and fatty acids) will be evaluated as well as seed damage and seed tested for the presence of seed pathogens (especially Phomopsis).
Seed composition (nutrition) components (seed protein, oil, fatty acids, amino acids, and sugars) will be determined by near-infrared reflectance spectrometer (NIRS™). Macro- and micro-nutrient analyses in seeds will be performed using standard laboratory protocols. Seed germination will be evaluated by the Mississippi State Seed Testing Laboratory.
Under Objective 2, wheat will be planted as a cover crop between soybean plantings and evaluated for nutrient recovery and effect of the cover crop on next year’s soybean crop. Wheat will be planted at three planting dates with the first date broadcast planted prior to soybean harvest, the second planting right after soybean harvest and the third at the optimal wheat planting time. Soil samples will be collected two times, the first immediately after soybean harvest and the second after wheat termination prior to soybean planting. Soybean seed and wheat biomass samples will be analyzed for macro and micro-nutrient content. Soybeans will be planted into wheat residue with stand counts taken 15 days after planting. At early flower, leaf tissue will be sampled to determine nutrient composition. At maturity, yield will be measured for each plot.