Soil Management Strategies for Sustainable Corn Stover Harvest.

Corn (Zea mays L.) stover has been identified as a primary feedstock for cellulosic bioenergy production in the U.S. Midwest because of the vast area upon which the crop is grown. We conducted five years (2008 – 2012) of field research designed to quantify short- and long-term effects of stover harvest on Mollisols in central Iowa, U.S.A. Chisel plow and no-tillage practices were used to produce corn using standard, 75 cm row spacing and a population of 7.9 plants m² or in twin-row configuration with a population of 9.4 plants m². A single-pass combine was used to harvest grain and an average of 0, 3.9, or 6.0 Mg ha^-1 yr^-1 [LSD_(0.1) = 0.3] of stover from single-row or 0, 4.5, or 6.1 Mg ha^-1 yr^-1 [LSD_(0.1) = 0.3] of stover from twin-row treatments each year. SamplePoint software was used to estimate surface cover following the 2011 and 2012 harvest seasons. Average post-harvest cover for the three stover treatments was 94, 84, and 70% [LSD_(0.1) = 4.4] for single-row and 97, 86, and 77% [LSD_(0.1) = 3.4] for twin-row configurations. Photos before and after chisel plowing in 2012 showed that tillage decreased average residue cover to 27 and 33% for single- and twin-row treatments, respectively. Grain yields showed significant seasonal differences primarily due to rainfall amount and distribution, with the highest levels for both planting configurations being 12.5 Mg ha^-1 in 2010 and lowest being 8.5 and 8.7 Mg ha^-1 for single- and twin-row configurations in 2012. Tillage practice had no significant effect on grain yield for either planting configuration. Grain yield was increased by approximately 1 Mg ha^-1 for both row configurations when stover was harvested, presumably because of more efficient nutrient cycling.