Corn response to incremental applications of sulfate‐sulfur

Reports of sulfur (S) deficiency symptoms in corn (Zea mays L.) fields of the Red River Valley of North Dakota and Minnesota are increasing. Current soil tests cannot predict the availability of S correctly due to the presence of gypsum in soils of this region. Field trials were conducted to determine corn yield and S uptake response to incremental applications of S (0, 11, 22, 33, and 44 kg S ha–1) in the form of ammonium sulfate [(NH4)2SO4]. Corn yield and S uptake varied significantly between sites. Out of 12 sites, only two sites had the highest corn yield without S application. Corn grain S removal ranged between 11 and 17 kg S ha–1 at harvest. Fertilizer‐S (SO4) application did not result in a significant yield response. The current recommendation of 11 kg S ha–1 may be necessary to reduce the risk of future S deficiency across this region and compensate for the removal of S in grain due to the uncertainty of adequate plant available S.