Corn Residue Harvesting Effects On Yield Response to N Fertilization.

Removing corn (Zea mays L.) residue for use as livestock feed or as a bioenergy resource reduces the amount of residue remaining for soil surface protection and alters the cycling of nutrients. This could affect nutrient availability for crop use. The project evaluated the effects of tillage and corn residue removal on corn yield response to N fertilization in continuous corn. The study was conducted at two sites in Iowa with different soil conditions and drainage class; with chisel plow tillage and no-till as the main plots, corn residue removal subplots (0, 50 and 100% removal), and six early sidedress N rates as sub-subplots (0 to 275 kg N ha^-1 in 55 kg increments). In 2009, tillage had no effect on corn yield across sites; however, removing corn residue increased corn yield by 0.43 and 0.68 Mg ha^-1 for the 50 and 100% removal, respectively, compared to no residue removal. In 2010, tillage increased corn yield by 0.79 Mg ha^-1 compared to no-till, and residue removal increased corn yield by 0.86 and 1.24 Mg ha^-1 for the 50 and 100% removal, respectively. Tillage had no effect on the maximum N response rate in either year. The 50 and 100% residue removal reduced the maximum N response rate in 2009 by approximately 30 kg N ha^-1, compared to no residue removal. In 2010, no difference in N rate response could be determined between the 0% and 50% residue removal as the N response was to the highest applied rate; however, the maximum N response rate for the 100% removal was at 242 kg N ha^-1, less than the highest applied rate. Results of the first two years indicated that corn residue removal and tillage increased corn yield, tillage did not affect N response, and residue removal reduced the needed N fertilization rate.