Long-term tillage effects on runoff and soil erosion under simulated rainfall for a central Ohio soil

Adoption of soil resource management and agricultural practices that seek to conserve soil and water resources and minimize environmental degradation is attracting overwhelming interest among scientists and the general public. Research data, long-term experiments and land use experience are pre-requisites to draw solid conclusions with regard to changes in soil physical and chemical properties. Experiments were conducted in 1994 to determine soil erodibility, soil and water runoff, and leaching characteristics of a Wooster silt loam following 32 years of continuous corn (Zea mays, L.) production at Wooster, OH, USA. Undisturbed soil cores of 250 mm diameter and 150 mm depth were extracted immediately after corn harvest from plots sown with three tillage methods, i.e. mouldboard ploughing (MP); chisel ploughing (CP); and no-till (NT). Soil cores were subjected to two events, 24 h apart, of 'simulated rainstorm' of 50 mm each at an intensity of 50 mm h(-1). Soil erosion and surface runoff were markedly affected by tillage practices in the order of MP > CP > NT and in a ratio of 4.4:2.9:1 and 1.85:1.6:1, respectively. The volume of leachate were found to be NT > CP > MP, and were 0.561 m(-2) in NT, 0.21 m(-2) in CP, and 01 m(-2) in MP. Previously wet soil conditions enhanced soil and water runoff but decreased soil splash. Soil splash was 2.5-fold higher in MP than in CP and NT. Not unexpectedly, soil and water runoff and leachate increased significantly after the initial 30 min of rainstorm. Surface runoff pH was 6.7 in NT compared with MP and CP which were at 7.0, suggesting that in NT surface soil became somewhat acidic possibly because of continuous surface application of fertilizer. Tillage methods had no effect on pH of the leachate. (C) 1997 Elsevier Science B.V.