Yield, nutrient, and soil sulfur response to ammonium sulfate fertilization of soybean cultivars

Abstract With the reduction of sulfur levels in high‐analysis nitrogen (N) and phosphorus (P) fertilizers and in atmospheric deposition, sulfur (S) fertilization may become more important, especially with intensive cropping systems. When high clay content is likely to limit root development into the subsoil, low extractable sulfate‐sulfur (SO4‐S) levels in the topsoil may suggest possible plant response to S fertilization. Even though ammonium sulfate [(NH4)2SO4] is widely used and readily available for plant uptake, field data are limited on the use of (NH4)2SO4 as an S source for soybeans [Glycine max (L.) Merr.]. A study was initiated to determine the effect of S fertilization as (NH4)2SO4 on: (i) the yield, seed weight, grain quality, and leaf and whole‐plant nutrient concentrations of four soybean cultivars grown on soils with high clay content subsoils; and (ii) selected soil chemical characteristics. Sulfur rates were 0, 28, 56, and 84 kg/ha, and soybean cultivars were two Maturity Group IV beans, ...