Wind Erodibility, Soil Moisture, and Freeze-Thaw Frequency: Implications of Harvesting Corn Residue for Energy Feedstock in Southwest Kansas.

Dependence on foreign oil has led to increased interest in 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. 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 0.23 Mg ha^-1. The objective of this experiment is to determine the impact of residue removal, by conventional methods (stalk chop, rake, and round bale) on the wind erodibility and precipitation capture and storage of two productive and important irrigated agricultural soils of southwest Kansas. Residue was harvested in October 2008 from two producer-owned fields with differing soil textures.   Sensors were installed in plots to monitor soil temperature and moisture. Bulk density, gravimetric moisture, dry aggregate stability, and soil roughness were determined in December 2008 and April 2009. Generally, soil temperatures were slightly warmer (about 1°C) and slower to warm up in the spring time where residue remained on the soil surface.  Soil moisture measurements were mostly higher where residue was harvested versus non-removed plots.  On April 23, 2009, at the time of corn planting, a difference of 0.032 volumetric water content was observed between the residue harvested and residue removed plots.  A strip tillage operation in February 2009 roughened the soil surface. Evidence of wind erosion in plots where residue was harvested included loose sand on physical crusts and soil deposition on the leeward side of remaining residue.