Wednesday, 9 November 2005
9

Management System Effects on Water Infiltration and Density of Two West Texas Soils.

Deanna Halfmann1, Ted Zobeck1, Richard Zartman2, and Vivien Allen2. (1) USDA-ARS, 3810 4th St., Lubbock, TX 79415, (2) Texas Tech University, Plant and Soil Science Department, P.O. Box 42122, Lubbock, TX 79409-2122

Soil and water conservation are important issues on the Southern High Plains because of limited rainfall and wind erosion. This study was conducted to determine if alternative management styles of ranching and farming may help conserve natural resources by allowing for increased water infiltration and improving soil physical properties. Bulk density and penetration resistance to 30 cm depths and water infiltration rates, using a double-ring infiltrometer, were measured on a Pullman clay loam under an integrated livestock-crop rotation, and an Amarillo loamy fine sand, under no-till dryland and irrigated cotton, conventional tillage dryland cotton, CRP, and native rangeland systems. Penetration resistance and bulk density were associated by depth but not by management system on the clay loam soil. The resistance increased with depth, reaching its maximum mean value at 15 cm (1.26 MPa), lowered at 20 cm (1.16 MPa) and remained fairly constant throughout the 20-30 cm depth to about 1.10 MPa. The mean bulk density values increased through the top 15 cm from 1.17 Mg m-3 to 1.42 Mg m-3, before lowering in the 15 to 30 cm depths (1.36 MG m-3). The infiltration rates (ranging from 0.34 cm h-1 to 2.62 cm h-1) seemed independent of the penetration resistance and bulk density because the systems with the highest resistance and bulk densities did not have the lowest infiltration rates. On the loamy fine sand soil, the native range had the lowest penetration resistance (<0.66 MPa) and bulk density (1.51 Mg m-3) and highest infiltration rate (9.35 cm h-1). The conventional tillage system had the highest resistance (>0.81 MPa) and bulk density (1.64 Mg m-3) and the lowest infiltration rate (1.18 cm h-1). The no-till irrigated and CRP systems were more comparable to the native range, while the no-till dryland system was more comparable to the conventional tillage system.

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