Tillage effects on soil properties and crop production in southern Illinois

Accelerated erosion is major environmental and economical problem throughout the world. In this study, the presence and concentration of fly ash, the product of high temperature coal combustion, and magnetic susceptibility in soil profiles of the cultivated and the uncultivated sites were used to estimate the soil loss due to accelerated erosion since European settlement. The primary source of fly ash was assumed to be the coal-powered rail service in the area which started in 1855. The results indicate the removal of 10.6 cm or 47 percent of the plow layer (22.5 cm) since 1855 (142 years) due to accelerated erosion at the cultivated site which placed the study site in moderately eroded phase of Grantsburg (fine-silty, mixed, mesic Typic Fragiudalf) soil with an estimated soil loss of 12.8 Mg/ha/yr.; On these sloping and previously eroded soils, the long-term maintenance of soil productivity with the moldboard plow system is a great challenge. A project was initiated in the spring of 1989 to determine the effects of three tillage systems: no-till (NT), chisel plow (CP) and moldboard plow (MP) with a corn-soybean rotation on the soil properties including different fractions of organic matter, crop production, and soil quality. After 8 years the soils with the NT system had less soil erosion due to higher surface residue. Crop yields with the NT system were higher in the fourth through eighth years of study. Based on 8 years of crop yield data, the NT system appears to result in improved long-term productivity compared to the MP and CP systems.; The 8 years of continuous CP and MP systems resulted in the loss of water-filled soil porosity due to decreased soil aggregate stability whereas the NT system maintained its water-filled soil porosity. Bulk density of soil in the NT system was higher due to reduction in the air-filled soil porosity. Exchangeable K was lower in the NT system than the CP system in the 0-5 cm layer probably due to higher leaching and runoff. Eight years of tillage resulted in a significant reduction in aggregate stability and different fraction of organic matter (particulate and mineral associated organic matter) in the 0-5 cm soil layer of the MP and CP systems. The NT system maintained soil organic C and aggregation over the 8 years.; The Harris et al. (1996) soil quality index (SQI) model was tested and modified according to local and regional conditions by changing the threshold limits and standardized scoring functions (SSF) for soil quality indicators. Soils that had been in 8 years of the NT system had SQI of 0.64 as compared to 0.52 in the CP and MP systems. The MP system had a higher rooting relations rating than the NT system whereas the NT system had better water (erosion resistance) and nutrient relations rating than the MP system. The MP and the CP systems had water relation rating of 0.25 and 0.21 than the NT system (0.60) showing that residue on soil surface is important for protection of soil against erosion. (Abstract shortened by UMI.)...