Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 1995
Publication Date: N/A
Technical Abstract: We measured surface soil hydraulic properties on three replicate plots of each of four rotation-by-tillage treatments established in 1982. Rotations were wheat-sorghum-fallow (WSF), and wheat-fallow (WF); and tillage treatments were either no-tillage (NT) or conventional (stubble mulch) tillage (CT) on each rotation. At 3 or more sites in each plot, a 20-cm diameter disk infiltrometer was run to steady state at each of 4 tensions. Bulk density and water desorption were measured on undisturbed cores using hanging water column and pressure plate methods to 100 kPa tension. Tension infiltrometer data were analyzed by nonlinear optimization to obtain hydraulic conductivities (K). Water retention and K data were then fit to van Genuchten's and Mualem's equations with r**2 of 0.99. Bulk density was significantly greater in NT than CT and significantly greater in WSF than in WF (10% prob. level). Saturated water content was significantly lower in NT than CT, and for NT plots it was significantly lower for WSF than for WF. Saturated K was significantly higher for CT than for NT in WSF rotations but not in WF rotations. However, the overall fitted K(theta, volumetric water content) curves showed that K was greater in CT than in NT for both WF and WSF rotations over most of the water content range from 0.1 to 0.5 m**3 m**-3.