Planting date effects on soybean yield and foliar nutrient concentrations across the Mid-Atlantic region

Abstract

The effect of three planting dates on soybean (Glycine max L. Merr.) yield and foliar nutrient concentrations was evaluated across four sites representing the Coastal Plain, Piedmont, and Ridge and Valley regions of the Mid-Atlantic. Group IV soybeans were planted at 2-week intervals from mid-April to late May. Trifoliate leaves and surface soils (0–15 cm) were sampled at the R2 stage. Although yield did not differ significantly among planting dates, several foliar nutrient concentrations were affected. Foliar K, Ca, S, and Fe declined with later planting, though all remained within sufficiency ranges. Only S showed parallel declines in both soil and tissue, suggesting a possible link between soil availability and plant uptake, though loss pathways and timing of availability should be further explored. Foliar Al concentrations were highest with early planting, despite soil pH >5.5, potentially reflecting early-season stress or increased availability. Correlations between nutrients and yield were weak overall, but Mn, Al, and Fe showed planting date-specific trends. These results indicate that while the planting window from mid-April to late May is suitable for soybean in the Mid-Atlantic, nutrient dynamics—especially for metals and immobile nutrients—are strongly influenced by planting timing and early-season conditions.