Corn Yield as Affected by Sulfur Fertilization in Southern Minnesota.

Historically, sulfur (S) fertilizer has not been recommended on medium- and fine-textured soils in Minnesota, because yield responses to S fertilization were found only on coarse textured soils. Mineralization of S from organic matter in fine-textured soils was generally sufficient to optimize corn yields in past trials. The increasing frequency of greater than 12.5 Mg ha^-1 corn yields along with decreased S additions from various sources (atmospheric deposition and manure application) have reduced the amount of available S in many soils of the Midwest. The objective of this paper is to document corn yield responses to S fertilization on medium- and fine-textured soils in Minnesota. Initial studies were conducted from 1999 through 2006 on tile drained Nicollet-Webster clay loam soils (Aquic Hapludolls and Typic Endoquolls, respectively). In one 6-yr study average corn grain yields were increased 0.5 Mg ha^-1 by an annual broadcast application of 90 kg S ha^-1 as gypsum.  In a 3-yr trial corn yield responses of 0.9 to 1.1 Mg ha^-1 were obtained in 2 of 3 years with planter band rates of 5 and 11 kg S ha^-1. These data support findings in other Iowa and Minnesota studies and suggest fertilizer recommendations for S on medium- and fine-textured soils should be revisited.