28 YEARS OF TILLAGE EFFECTS ON 2 SOILS IN OHIO

Evaluation of soil physical properties was conducted on soil sampled in 1990 from long-term tillage experiments established in 1962 on silt loam soils at Wooster and South Charleston, OH. Tillage treatments included: moldboard plowing (MP), chisel plowing (CP), and no-till (NT). No-till treatments had significantly (P = 0.05) more organic C accompanied by a similar increase of cation-exchange capacity (CEC) in the 0- to 15-cm layer in both sites than other tillage methods. High bulk density and penetration resistance were measured in the traffic zone (TZ) compared with the row zone (RZ) in the top 15 cm under NT treatments. The mean hydraulic conductivity in NT plots was 12 times more than CP and MP for TZ and 15 times more for RZ. The aggregation percentage and mean weight diameter (MWD) were significantly (P = 0.05) more in NT compared with other treatments in both zones and sites. The available water-holding capacity (AWC) was in the order of NT > CP > MP, with significant differences among treatments. The mean AWC in NT plots was 24% more than CP and 23% more than MP for RZ, and 8% more than CP and 11% more than MP for TZ.