Thursday, November 16, 2006 - 9:55 AM

Soil Hydraulic and Electrical Properties for Different Soils, Slopes, and Crop Rotations.

Sally Logsdon, USDA-ARS, USDA-ARS Natl Soil Tilth Research Laboratory, 2150 Pammel Dr., Ames, IA 50011

Crop management can alter soil physical properties, but variability of these properties may mask treatment effects. The purpose of this study was to compare soil physical property variation under two crop rotations, and to examine interrelations among different soil physical properties. A six year rotation (corn, soybean, corn, three years alfalfa: W2) was compared with a corn - soybean rotation (W1), both under no-tillage. Five soils and thee slope phases were represented on these fields. Soil physical properties measured from undisturbed cores included saturated hydraulic conductivity (Ksat), bulk density (BD), apparent permittivity (n), electrical conductivity (EC), and macropore continuity. Preliminary data suggest that cores with continuous macropores had significantly higher Ksat, but there was no significant difference in Ksat between W1 and W2. W1 had significantly higher air-filled porosity but lower EC and n than W2. Both n and EC increased with increasing water content, but the relationships varied with different groups of samples. Soils with D slopes had significantly lower Ksat than soils with B slopes. The interrelations will be discussed as well as the most useful soil physical measurements for evaluating crop management systems.