Double-crop soybean management practices for high yield and profitability

Double-crop soybean[Glycine max (L.) Merr.] production in Kentucky involves planting soybean after soft red winter wheat (Triticum aestivum L.) harvest during June and July. Double-crop soybean yields are lower than full-season soybean yield planted earlier in the spring. This research aimed to determine the effect of seeding rate, seed treatment, and applying foliar fungicide and insecticide at the R3 growth stage at two planting timings on double-crop soybean seed yield, yield components, and seed quality. Field trials were established in Princeton, KY, in 2017, 2018, and 2019 after wheat harvest. Planting double-crop soybean early, after wheat was harvested at 20 to 22% grain moisture, resulted in increased seed yield, seeds ft^–2, and protein concentration compared with double-crop soybean planted later. A seeding rate of 225,000 seeds acre^–1 resulted in increased seed yield, seeds ft^–2, and seed protein concentration compared with 150,000 seeds acre^–1. A seed treatment including fungicides and an insecticide did not impact seed yield, yield components, or seed protein or oil concentration compared with no seed treatment. Applying a prophylactic foliar fungicide and insecticide treatment at the R3 growth stage increased seed yield and seed mass compared with an economic threshold application. In addition, the most intensive management (225,000 seeds acre^–1, seed treatment, and prophylactic fungicide and insecticide) yielded ∼25% more than the base treatment and had more seeds ft^–2. The results are the first to indicate the potential for intensive management practices to increase double-crop soybean productivity in Kentucky.