Continuous corn response to residue management and nitrogen fertilization

Harvesting corn (Zea mays L.) residue in continuous corn (CC) may require changes in crop management for increased efficiency. Experiments were conducted in Illinois to determine how residue removal and tillage affect surface residue after planting and the response of CC to N fertilization. Partial removal of residue left 21 to 26% surface residue coverage with a chisel plow system, compared with 53 to 65% with no-till. Across 2 yr with 92 to 128 mm rainfall during June and July, grain yield only responded to N fertilization with no-till. When compared with full removal of residue in no-till, no removal increased the economically optimum N fertilizer rate (EONR) by 58% and yield at the EONR from 8.6 to 10.3 Mg ha^-1. Across five environments with 201 to 264 mm rainfall during June and July, yields with full removal of residue were 13.1 Mg ha^-1 with no-till and 13.4 Mg ha^-1 with tillage. With partial and no residue removal, yields were 5 and 12% greater with the chisel plow than with the no-tillage system, respectively. Across tillage systems in these environments, retaining all residue increased the EONR by 13% and decreased yield at the EONR by 4% when compared to full or partial removal of residue. On productive soils with adequate rainfall, removal of residue has the potential to raise yields and to lower N fertilizer requirements in the short term. This advantage, however, needs to be balanced against the need to retain adequate soil cover to maintain soil productivity.