Corn Response to Sulfur Fertilizer in the Red River Valley

The recent incidence and severity of sulfur (S) deficiency due to a decrease in atmospheric S deposition and greater S removal by crops requires reevaluating current S recommendation for corn ( Zea mays L.). Ten on‐farm field trials were conducted to evaluate corn response to S additions at sites in the Red River Valley of North Dakota and Minnesota between 2016 and 2017. Sulfur rates of 0, 11, 22, 33, 44 kg S ha –1 as granular (NH 4 ) 2 SO 4 were broadcasted and incorporated prior to corn planting using randomized complete block design with four replications. Plant tissue S concentration and N/S ratios were determined at two corn growth stages (V6 and V12 in 2016, V12 and R1 in 2017) and grain yield was measured at harvest. Plant tissue S did not increase with S fertilizer at V6 and V12 stages in 2016 whereas in 2017, tissue S increased with 11 kg S ha –1 at two sites in the V6 growth stage. Yield was not related to both soil S and plant parameters. Corn yield increased with 11 kg S ha –1 fertilizer rate at two of ten locations. Lack of response at the remaining sites suggests that S from organic matter and mineralization was enough for crop growth and hence applied fertilizer S had no effect on yield. Core Ideas Corn grain yield increased with S fertilizer at two of ten sites. No response to S fertilizer occurred due to dry early growing season. Plant tissue tests were not reliable indicators in predicting response.