Corn Response to Sulfur Fertilizer.

Growing sulfur (S) deficiency across the North Dakota region requires to revise S fertilizer recommendation for corn. The decrease in atmospheric S deposition in addition to large S removal by corn and soybean results in depletion of soil available sulfur. On-farm field trails were conducted to evaluate the corn response to S additions in the Red River Valley of ND and MN at five sites in 2016. Five sulfur rates of 0, 10, 20, 30, 40 lb SO₄-S/ac in a randomized complete block design with four replications were used. Ammonium sulfate was used as sulfur source and fertilizer was broadcasted and incorporated before planting. Along with corn yield, leaf S concentration at V6 and V12 stage were determined. Significant yield response to fertilizer S application was observed at one out of five sites but no correlation was observed between leaf S concentration and yield. Our results indicate corn sulfur response varies from site to site depending on soil characteristics and corn leaf S concentration can not truly predict corn yield.