Landscape and conservation management effects on hydraulic properties of a claypan-soil toposequence

Information on the effects of landscape and its interaction with management on soil hydraulic properties is scarce. Our objective was to investigate the effects and interactions of landscape position and conservation management systems (e.g., reduced tillage or permanent grass) on soil bulk density, saturated hydraulic conductivity (K soil water retention, and pore-size distributions for claypan soils in central Missouri. Landscape positions included summit, backslope, and footslope positions. Management included mulch tillage with a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation (MTCS); no-till with a corn-soybean-wheat (Triticum aestivum L.) rotation (NTCSW) with a red clover (Trifolium pretense L.) cover crop following wheat; a Conservation Reserve Program system (CRP); and a hay crop system (HAY). Intact soil cores (76 by 76 mm) were collected from 0- to 10-, 10- to 20-, and 20- to 30-cm depths. Soil properties were affected by management only in the surface 0 to 10 cm, and were controlled by the depth of the claypan horizon. Management and depth effects on soil properties varied with landscape position. Saturated hydraulic conductivity was highest for CRP and lowest for MTCS (20.2 vs. 4.3 mm h(-1)), averaged across all landscape positions and depths. T e management x landscape position interaction indicated that, at the backslope, A;at values for CRP and HAY were 16 and 10 times higher, respectively, than values for MTCS. The CRP retained the most water at soil water pressures from saturation to -1 kPa at the 0- to 10-cm depth. The fraction of larger pores was the highest for CRI? at the 0- to 10-cm depth. Results suggest that the use of perennial grasses in rotation (or permanently) will benefit soil hydraulic properties, particularly at slope positions most vulnerable to degradation where soil conditions cannot be improved by row-crop conservation systems.