Effect of Crop Residue Removal Rate On Micronutrient Availability and Soil Quality.

Corn stover is a potential alternative feedstock for bioenergy and bio-based products, but high residue removal rates may lower the sustainability of the cropping system.  The objectives of this work were to: 1) evaluate availability of the secondary nutrients Ca, Mg, S and micronutrients Zn, Fe, Cu, and Mn, and 2) determine changes in soil quality indicators, under continuous corn with different rates of residue removal. Data were collected at Rosemount, Lamberton and Northfield, MN. Treatments were two tillage systems (conventional-till and strip-till) and 3 residue removal rates (0, 50 and 100% removal). Plant nutrient removal was greater in the 100% than 50% removal rate for all locations. After two years of removal treatments, there were some differences between removal rates in soil micronutrient availability.  There were no significant differences between tillage systems in the availability of soil macro and micronutrients. Small differences in soil availability of some micronutrients appear to be related to variations in pH and OM content. In the short-term (after 1-2 yrs of establishment) soil quality indicators (potentially mineralizable C and N, and particulate organic matter C and N) reflected differences between tillage treatments due to stratification under strip-till systems compared with conventional-till systems, but no differences were detected due to residue removal rates, except in  Northfield, where the concentration of POM-C was the same for the 0% and 50% removal rate, but significantly greater than 100% removal.