Implications of Harvesting Corn Residue for Energy Feedstock in Southwest Kansas On Soil Quality, Wind Erosion, and Soil Water.

Dependence on foreign oil has led to increased interest in renewable sources of bioenergy and the harvest of crop residues for the production of cellulosic ethanol. Crop residue has many important functions in production agriculture systems, among which are protection of the soil surface from wind and water erosion and minimizing water evaporation. A proposed cellulosic ethanol plant in southwest Kansas will require an estimated 444,000 Mg of biomass annually, the majority of which will initially be supplied by the harvest of crop residues. In 2007, irrigated corn production was the dominant land use in Stevens County, KS, comprising 22% of the land area, and 38% of the harvested ha, with an average irrigated grain yield of 12.79 Mg ha^-1. The objective of this experiment was to determine the impact of residue removal, by conventional methods (stalk chop, rake, and round bale), on the wind erodibility, soil quality parameters, and precipitation capture and storage of two productive and important irrigated agricultural soils of southwest Kansas. Residue was harvested in October 2008 and December 2009 from two producer-owned fields with differing soil textures.  Sensors were installed in plots to monitor soil temperature and moisture. Bulk density, gravimetric moisture, wet aggregate stability, fertility levels, and residue measurements were collected following residue harvest in 2008 and 2009.  Wet aggregate stability, bulk density, and soil fertility levels were measured to depths of 15 cm.   Generally, soil temperatures were slightly warmer (about 1°C) and soil moisture was greater beneath crop residue at both sites.  Differences in wet aggregate stability were observed in the first year, but none of significance.   Residue harvest increased susceptibility to wind erosion due to breakdown of soil aggregates at the surface.  Soil sensor data indicated differences in frequency and length of freeze thaw cycles in plots where residue was harvested.  Only small variances in soil fertility levels were observed at both sites.