Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/1996
Publication Date: N/A
Technical Abstract: No-till reduces surface runoff on many but not all soils. This work presents results of a study conducted at the McCredie Claypan Experimental Farm where 40 natural rainfall erosion plots have been in continuous operation since 1941. Study objectives were to: (1) measure the hydraulic conductivity (Ksat) of the Ap horizon as affected by 7 long-term cropping, tillage, and wheel-traffic treatments, (2) analyze 11 years (1983-1993) of surface runoff data, and (3) determine relationships between Ksat and runoff. Results indicate that tillage had a small but significant effect on runoff, Ksat, bulk density, water content, and organic matter. Continuous fallow (F) produced the lowest values of Ksat (3 mm/h), bulk density (1.3 Mg m**-3), and organic matter content (0.9%) for the Ap horizon. No differences in Ksat were found among other tillage treatments. Runoff under F was the highest of all tillage treatments. The greatest amount of runoff occurred from harvest to planting. No-tillage had significantly higher runoff than moldboard (MP) and chisel plow (CP) treatments. Runoff from MP was significantly lower than that from CP during the fallow period. Results indicate that differential surface runoff can be partly explained by the differences in surface residue and soil water content.