Continuous Corn Response to Residue, Sulfur, and Nitrogen Management.

High corn prices have caused some growers in the northern Corn Belt to adopt continuous corn cropping systems. Improved hybrids have improved overall plant health and decreased pest levels, potentially leading to hardier crop residues. This, in combination with higher levels of residue production and the adoption of continuous corn, have resulted in more corn residue present at planting. Recently, growers have started to incorporate fall applications of N and S with stalk chopping and aggressive tillage to manage residues. There is little evidence to support the value of applications of N and S as practices to reduce residue levels in the spring. The objective of this study is to evaluate S and supplemental N fertilizer on fall corn residue in a continuous corn system under chopped and unchopped corn residue treatments. To accomplish this, a two-year study was initiated at two Minnesota locations in 2011 and 2012. The study was a complete factorial, including unfertilized controls, with main plots being chopped or unchopped corn residue. Treatments included supplemental applications of fall- and spring-applied N and S. Fall and spring applications of S were applied at 17 kg S ha^-1. Supplemental applications of N were applied at a rate of 34 kg N ha^-1 using urea ammonium nitrate in the spring and fall. Additional applications of N were applied at 190 kg N ha^-1 of urea in the spring to ensure adequate N for crop production. Residue bags were buried the previous fall in select plots to measure residue decomposition of four specific treatments within the main plots. Bags were removed at select growth stages throughout the growing season for analysis.  Plant nutrient analysis of N and S were completed at four growth stages throughout the growing season. Other data collected included grain yield, moisture and soil residue coverage.