TILLAGE AND CROP EFFECTS ON PONDED AND TENSION INFILTRATION RATES

Tillage and residue management practices influence soil surface compac tion and sealing, but the effects vary with time and weather history. The objective of this study was to compare surface ponded and tension infiltration rates for different tillages and crop rotations at variou s dates in a Kenyon loam. Four tillage systems (minimum tillage (no-ti ll system with two cultivations), chisel, moldboard plow, and ridge-ti ll) and two rotations (continuous corn and soybean-corn rotation with corn in 1991) were examined. Ponded and tension infiltration rates wer e measured in the row at four dates: 18 June 1991, 9 July 1991, 23 Sep tember 1991, and 11 May 1992. Soil was collected for measurement of ag gregate stability and undisturbed soil cores were collected for measur ements of saturated hydraulic conductivity and bulk density on the fir st measurement date to relate the infiltration measurements. Minimum t illage had significantly faster ponded infiltration than chisel or mol dboard, as well as greater aggregate stability and less bulk density a t that date because of reduced surface sealing. Tillage and crop rotat ion effects on infiltration for the other measurement dates were incon sistent. When the measurement dates were compared, ponded and tension infiltration rates for the first measurement date were less than for m easurements at later dates because of a surface seal which was not pre sent at the later dates. Temporal changes in infiltration were greater than tillage or rotation differences. To quantify management effects on surface soil properties we conclude that several well documented me asurements are required. If possible, the measurements should be taken soon after rainfall events.