Impact of Corn Stover Removal on Soil Microbial Community Composition in a Long Term, Irrigated, Continuous Corn Production System.

Corn (Zea mays L.) residue, or stover, can be used as a dry forage replacement in beef cattle diets and is being considered as a feedstock for cellulosic biofuel production. The soil quality and crop productivity ramifications of removing stover, however, likely will depend on stover removal rate and other management practices (i.e. tillage). Our objectives were to evaluate the impacts of stover removal rate and tillage on soil microbial communities by profiling microbial fatty acid methyl esters (FAMEs) in a 10-yr, irrigated, continuous corn study in the western Corn Belt (Ithaca, NE).  Microbial FAMEs were used to estimate soil microbial biomass and evaluate soil fungal:bacterial ratios throughout the 2014 growing season under conventional disk tillage (CT) and no-till (NT) with variable stover removal rates (none, moderate, and high). Disk tillage resulted in higher total microbial biomass compared to no-till soils when all residue was removed. In contrast, total microbial biomass did not differ between tillage treatments for low or moderate residue removal rates. The ratio of fungi to bacteria was consistently greater in plots that were disked compared to plots that were no-till across any level of residue removal and the greatest in plots where no residue was removed. Understanding how the removal of corn stover affects soil microbial communities, and in turn, soil quality, can aid in the development of corn stover removal thresholds which maintain or improve soil quality while providing a necessary feedstock for bioethanol production.