Influence of Corn Stover Harvest On Soil Quality Assessments At Multiple Locations Across the U.S.

Corn stover has been identified as a biofuel feedstock due to its abundance and a perception that the residues are unused trash material.  However, corn stover and other plant residues play a role in maintaining soil quality (health) and enhancing productivity, thus use of this abundant material as feedstock must be balanced with the need to protect the vital soil resource.  Plant residues provide physical protection against erosion by wind and water, contribute to soil structure, nutrient cycling, and help sustain the soil microbiota.  Replicated plots were established on productive soils at several locations (Iowa, Indiana, Minnesota, Nebraska, Pennsylvania, South Dakota, and South Carolina) and a multi-year study was carried out to determine the amount of corn stover that can be removed while maintaining the current level of soil quality for each soil.  These sites represented a range of soil types and climatic conditions, and have been ongoing for and least five years with some much longer studies.  All sites had at least three levels of stover harvest: grain only (control), maximum removal (90-100%) and a mid-range removal rate (~50%).  The Soil Management Assessment Framework (SMAF) will be used to score and assess changes in soil health. Preliminary examination of the data shows that removal at the highest rates results in a loss in soil quality. current data will be supplemented by concurrent studies at multiple locations designed to determine the impact of conservation practices on soil quality as well as a synthesis of existing literature.