Influence of Long-Term No-Tillage on the Physical Properties of an Ultisol

No-tillage cultivation offers significant advantages over con­ ventional tillage in terms of water, energy, and particularly soil conservation (Francis et al., 1987). However, continuous no-tillage farming on sandy Ultisols may lead to high bulk density that has a pronounced effect on soil strength due to traffic compaction and lack of plowing (NeSmith et al., 1987). This increase in soil strength under no-till cultivation might have a significant effect on root distribution. On sandy loam soils with good soil structure, greater root density has been reported in no-till as compared to conventional systems (Fran­ cis et al., 1987). In contrast, on structurally unstable soils, the presence of a high-strength, root-impeding layer can lead to proliferation of roots above this layer resulting in a greater root density in the top soil of plowed than in no-till soils (Fran­ cis et al., 1987). Infiltration of rainfall into the soil is important, both in supplying water to the root zone and in preventing excessive ero­ sion due to high runoff volumes. In the southeastern United States, infiltration rates on bare soils are typically low, due to crusting of the highly weathered, poorly structured soils (Miller and Bahruddin, 1986). However, infiltration of water into these soils is usually higher under no-tillage than in con­ ventional tillage (Hargrove, 1985). The objective of this paper is to examine the effect of longterm continuous no-tillage on physical properties, with em­ phasis on the effect of no-tillage on infiltrability of these soils.