Soil compaction and tillage effects on soil physical properties of a mollic ochraqualf in northwest Ohio

Soil compaction affects crop yields through alterations of soil physical properties and processes. Effects of 3 tillage methods and 3 compaction treatments on the physical properties of a clayey soil were investigated in the lakebed region of northwestern Ohio. Tillage treatments included no-till (NT), chisel plowing (CP), and moldboard plowing (MP). Compaction treatments were imposed for 3 consecutive years followed by 4 years without compaction. Compaction treatments involved control, 10 Mg, and 20 Mg axle load on single axis. Effects of tillage las main plots) and axle load (as sub-plots) treatments were evaluated for 2 crop rotations: a 3-year rotation involving corn (Zea mays)-soybean (Glycine max)-oats (Avena sativa) and a 2-year rotation involving corn-soybean. These experiments were initiated in fall 1987, and measurements of soil physical properties were made in 1992 and 1993. Neither tillage nor compaction treatments had a significant effect on soil bulk density (rho(b)), and mean rho(b) measured in 1993 was 1.34 Mg m(-3) for 0 to 10 cm depth and 1.39 Mg m(-3) for 10 to 20 cm depth. Although not significantly different, trends in rho(b) were NT > MP > CP for 0 to 10 cm depth and NT > CP > MP for 10 to 20 cm depth. The data on saturated hydraulic conductivity (K-S) were highly variable and treatments had no effect. Moisture retention characteristics differed significantly among depths but not among treatments. The data highlight the need for development of suitable indices for or to assess management-induced differences in physical properties of clayey soils characterized by high swell-shrink capacity.