Tillage and Rotation Effects on Soil Physical Characteristics

Farmers are adopting different cropping systems, so our objective was to identify tillage × rotation interactions for soil physical characteristics in the sixth year of a tillage (moldboard plow, chisel, and ridge) × rotation {continuous corn (Zea mays L.), soybean [Glycine max (L.) Merr.]–corn and soybean–wheat (Triticum aestivum L.)/clover (Trifolium pretense L.)–corn} study. Moldboard plow had lower penetration resistance (0.97 MPa) and bulk density (1.19 g cm−3) and greater infiltration (75 μm s−1) and porosity (−2.5 to −40 kPa soil water potential) compared with ridge tillage (1.39 MPa, 1.31 g cm−3, and 24 μm s−1, respectively) at the sixth leaf (V6) stage and greater infiltration (106 and 31 μm s−1, respectively) during early grain fill (R3) of corn. In ridge tillage, the interrow had lower penetration resistance (1.10 Mpa) and bulk density (1.28 g cm−3) and greater infiltration (35 μm s−1) vs. the row (1.68 MPa, 1.34 g cm−3, and 13 μm s−1, respectively) at V6 but greater penetration resistance (3.13 and 2.46 MPa, respectively) at R3. The soybean–wheat/clover–corn rotation had the greatest earthworm densities (504 m−2) and infiltration (68 μm s−1) among rotations at V6. Earthworm densities and infiltration explained about 25% of corn yield variability, which may have contributed in part to the 15 to 40% yield advantage for corn in the soybean–wheat/clover–corn rotation in moldboard plow. Tillage × rotation interactions did not exist for soil physical characteristics, so 5-yr tillage effects would be consistent across rotations.