Tillage and Crop Rotation Phase Effects on Soil Physical Properties in the West-Central Great Plains

Efficient water use is the primary determinant of profitability in dryland crop production of the western Great Plains. For a sustainable increase in precipitation use efficiency (PUE) from that typical of the traditional winter wheat (Triticum aestivum L.)-fallow rotation with conventional stubble-mulch (sweep) tillage (CT) to occur, decreased use of fallow and tillage is required. Our objective was to quantify the effect of tillage intensity (no-till [NT], reduced tillage [RT], and CT) and phase of the winter wheat-grain sorghum [Sorghum bicolor (L.) Moench]-fallow rotation on selected sod properties that influence PUE, with emphasis on infiltration and the association between water-stable aggregates (WSA) and infiltration rate. Soil water content at -1.5 MPa matric potential, concentration of WSA >= 0.5 mm, mean weight diameter of WSA, and ponded steady-state infiltration rate were significantly greater with NT than RT or CT (infiltration rates: NT, 30.6; RT, 15.3; and CT, 11.4 mm h(-1)). Infiltration rate was significantly greater in the wheat phase (25.8 mm h(-1)) than in the sorghum (15.4 mm h(-1)) or fallow (16.2 mm h(-1)) phases. The significantly better conditions of aggregate stability and water infiltration with NT management and the lack of development of poor infiltration properties during the wheat season that would need to be alleviated by tillage after harvest reinforce the appropriateness of NT management in crop production systems of the region.