The Effect of Planting Date, Seeding Rate, and Seed Treatment On Grain Yield in Group II and III Soybeans.

An optimal plant population in soybean production is one that maximizes profit per acre. With increasing seed costs, growers are interested in reducing seeding rates. Fungicide seed treatments protect soybean seedlings from several soil fungi that cause seedling diseases and stand loss; using a fungicide seed treatment may allow growers to reduce seeding rates while achieving desired final plant populations. The objectives of this study were 1) to determine the optimum seeding rates for maximizing yield and profitability in soybeans at two planting dates, early and normal, and 2) to evaluate the benefit of using seed treatments to increase yield and/or safely reduce seeding rates. This study was planted at several Midwest locations. There were two targeted planting dates, early and normal. Three seed treatments were included, CruiserMaxxPak¹, ApronMaxx¹, and an untreated check. Seeding rates were 55,000, 110,000, 165,000, and 220,000 seeds/acre. The yield response in this study showed that late-April to early-May plantings produced the highest yield. The optimum economic seeding rate for the ApronMaxx and CruiserMaxx treatments were lower than the optimum economic seeding rate for the untreated check in the early planting date. The optimum economic seeding rate for the CruiserMaxx treatment was lower than the untreated check in the normal planting date. Income/acre was higher than the untreated check for all seeding rates for the CruiserMaxx treatment in both planting dates. Environmental conditions are different each year and vary from field to field making it difficult to make a standard recommended seeding rate for all situations.  Recommendations should be made based on current market price and individual field conditions.