Impacts of Residue Removal on Soil Quality in a Corn-Soybean Rotation Seeded with Cover Crops.

The present study was conducted to assess the impacts of corn (Zea mays L.) residue and cover crops on soil quality. The experimental site was located in Brookings County of South Dakota (SD) at the USDA-ARS North Central Agricultural Research Laboratory on a silty clay loam soil. The treatments included: three different residue removal rates: low residue removal (LRR), medium residue removal (MRR), and high residue removal (HRR) managed with and without cover crop. The LRR treatment consisted of harvesting only the corn grain, leaving all other plant materials on the soil surface, MRR consisted of harvesting the grain and then chopping the leftover stalks to be windrowed and baled, and the HRR consisted of cutting the stalks 0.15 m from the ground and removing that portion of the plant. Data from this study show that crop residue removal significantly impacted the soil properties, however, little differences were observed between cover crops and no cover crops. Corn residue removal and cover crop impacted soil properties such as soil organic carbon (SOC), microbial activity, water stable aggregates (WSA), and soil aggregate wettability for the 0-5 and 5-15 cm depths. The LRR treatment resulted in higher SOC concentrations thus enhancing the aggregate stability compared to other treatments (MRR and HRR). The effects of residue removal significantly impacted the microbe activity in the soil. Results from this study concluded that removal of high residue lead to SOC decomposition and affect soil properties and soil quality, therefore, maintaining LRR and using cover crops can improve soil quality. However, a longer period of time is needed to assess the full impact of cover crop and residue removal on soil quality.