Soil infiltration and hydraulic conductivity under long-term no-tillage and conventional tillage systems

Long-term tillage practices may affect crop growth, in part by changing soil hydraulic properties. The hypothesis that long-term no-till (NT) and conventional tillage (CT) practices affect soil infiltration and hydraulic conductivity was evaluated on silt loam and sandy loam soils (both Gray Luvisols). Ponded soil infiltration, water content and matric potential were measured in the field during 1992 and 1993. In most cases, the ponded soil infiltration rates (i) were significantly lower (P less than or equal to 0.05) under the CT than under the NT for both soils. Total volume of soil pores with radii < 14 mu m (micropores) were significantly greater in NT than in CT. Differences in volume of soil pores with radii > 14 mu m (macropores) between CT and NT were not significant. For the initial soil moisture conditions ranging from dry to field capacity, the i values were greater by 0.24 to 3.01 cm h(-1) in NT than in CT for the silt loam and by 3.30 to 4.13 cm h(-1) for the sandy loam. Saturated hydraulic conductivity values were significantly greater in NT (range from 0.36 to 3.0 cm h(-1)) than in CT (range from 0.26 to 1.06 cm h(-1)). Unsaturated hydraulic conductivity increased more with increasing matric potential (less negative) in NT than in CT. Long-term NT practices kept soil pore structure and continuity undisturbed, which contributed to significantly greater hydraulic conductivity and infiltration rates in NT than in CT for both soils.