Response of Corn to Residue Management and Nitrogen Fertilization.

Corn stover is targeted as a major feedstock for bioenergy production. However, stover removal can affect the growth and yield of a following corn crop and its response to N fertilizer. Stover removal may also influence the optimal tillage system with regard to yield and N-use efficiency. In southern Minnesota, concern about yield reductions due to cool, wet soil conditions, partially attributed to high amounts of crop stover, have limited the adoption of reduced-tillage systems for continuous corn. In the fall of 2008, a high-yield continuous corn study was established at the University of Minnesota Research and Outreach Center at Waseca on a Nicollet-Webster clay loam soil complex to investigate the effects of stover removal (full vs. no removal), tillage system (disk-chisel, strip- and no-tillage), and N fertilizer (six rates ranging from 0 to 269 kg N ha-1) on continuous corn growth and yield. Stover removal increased grain yield, as yield with full stover removal was 10.8 Mg ha-1 compared to 9.2 Mg ha-1 with no stover removal, averaged across tillage systems and N fertilizer rates. Tillage did not significantly affect grain yield in 2009. Stover removal and N fertilization also increased emergence, normalized difference vegetation index at the eight leaf collar stage, leaf chlorophyll at the tassel stage, and stover yield under all tillage systems. While stover removal increased yield in the short-term and did not affect the response of corn grain yield to N, long-term stover removal without organic additions could reduce long-term soil productivity and corn yield potential.