Soybean response to sulfur fertilizer applied as a broadcast or starter using replicated strip trials

Sulfur fertilizer is not recommended for soybean [Glycine max (L.) Merr.] production in the northern Corn Belt even though responses to S have been occurring more frequently in other crops. The objectives of this study were to determine the impact of fluid fertilizer combinations containing N, P, and S on early S uptake, soybean grain yield, and S removal and to evaluate various soil and plant tissue testing factors for predicting S need. Field trials were conducted at four locations, one with a sandy soil and three locations with finer soil textures. Preplant broadcast S was compared with liquid starter N and NP combinations applied with and without S 5 cm beside and below the seed row. Nitrogen increased soybean early plant mass while S increased plant S concentration, uptake, S removal in grain, and grain protein concentration but decreased seed oil concentration. Soybean grain yield was increased by S at one location and was not increased by N or P. Grain yield response to S occurred only when soil organic matter concentration was<20 g kg^-1. The factor best correlated to yield response to S was grain S concentration, followed by tissue S concentration at the R2 growth stage and whole-plant S concentration at the V5 stage. Extractable SO₄-S in the soil was negatively correlated to yield response to S. The data indicate that soybean plants will accumulate S in higher quantities than needed for growth and development and that yield response is possible under limited circumstances.