TILLAGE EFFECTS ON CORN PRODUCTION AND SOIL PHYSICAL CONDITIONS

Row crop production on highly erodible soils of the Piedmont in the southeastern USA is often limited by surface sealing, excessive surface water runoff, soil erosion, and low crop yields. The effects of four tillage practices on corn (Zea mays L.) growth and soil properties on two crust-prone soils were evaluated. Tillage treatments at two Piedmont locations, Oxford and Reidsville, NC, were no-till (NT), in-row subsoiling (IRS) (1987 only), chisel plow (CP), and moldboard plow-disk (MP). Residue cover was 1% for MP and ranged from 75 to 87% for NT and 38 to 27% for CP. The interaction between tillage, soil properties, and plant performance was complex. Mean bulk density of the Ap horizon at Reidsville for the 2-yr period was 1.56 Mg m(-3) for NT, compared with 1.48 Mg m(-3) for CP and 1.46 Mg m(-3) for MP. Cone index was not affected by tillage but was greatest in the trafficked interrow, 3.50 MPa, compared with 1.91 and 1.09 MPa in the row and nontrafficked interrow, respectively. Mean corn grain yield for the four year-locations was least, 1.23 Mg ha(-1), for MP, compared with 2.97 Mg ha(-1) for NT and 2.44 Mg ha(-1) for CP; mean yield for IRS in 1987 was 3.69 Mg ha(-1). Tillage practices leaving crop residues on the soil surface, such as NT, CP, and IRS, can reduce or eliminate surface crusting, increase infiltration, and reduce surface runoff and soil loss while increasing crop yield.