Northeast Research and Demonstration Farm
Multi-year results from the Northeast Research Farm suggest that mid-April to mid-May planting dates produce top soybean yields if soil conditions are ideal. Research farm trials have also shown that soybeans yield similarly over a wide range of seeding rates and harvest populations. Based on these results, some producers are planting soybeans as soon as spring field conditions allow, with a seeding rate of 150,000 to 175,000 seeds/acre. The yield response of modern varieties to early planting raises questions about expanding the soybean planting season to late March or early April when conditions allow. Producers considering early planting recognize the risk of stand losses caused by seedling diseases in cooler soils. In 2000 and 2002, a soybean “planting date x seed treatment” study was initiated to evaluate yield response of an adapted, high-yield variety to very early planting. Research objectives are to determine if fungicide seed treatments are needed to maintain high yields across several early planting dates.
Iowa State University
Pecinovsky, Kenneth T., "Seed-Applied Fungicides for Very Early-Planted Soybeans" (2003). Iowa State Research Farm Progress Reports. 1503.