PHYSICAL-PROPERTIES OF A CLAYEY COASTAL-PLAIN SOIL AS AFFECTED BY TILLAGE

A 4-year study was conducted to determine the effects of different tillage systems on physical properties of a clayey Coastal Plain soil. The systems no-till NT), fall moldboard plow-spring disk barrow (MB), and fall chisel plow-spring disk barrow (CP) were used in a winter wheat (Triticum aestivium L.), summer grain sorghum (Sorghum bicolor L. Moench) rotation on a Greenville sandy clay loam. Bulk density, saturated hydraulic conductivity, and soil moisture retention were determined on soil samples collected from the no traffic interrow areas of plots used concurrently for a rainfall simulator study of surface runoff and N movement. Examination of changes in the physical properties of the top soil zone (2.5-10.1 cm) showed that, after 1-1/2 years of tillage treatment and thereafter, the NT soil was different from the other two treatments. The NT top soil zone had significantly greater bulk density, lower saturated hydraulic conductivity, and held more water than the same soil zone on the other two treatments. Without tillage, the top soil zone of the interrow areas of this sandy clay loam soil bence was denser, harder, and bad more smaller sized pores than the same zone on the other two treatments. A final sampling using soil pits showed the NT treatment to be denser and have lower saturated hydraulic conductivity in the 15-38 cm depth zone. The NT had greater soil moisture retention than the other two treatments at depths greater than 30 cm. Rainfall simulator work on these same treatments showed greater infiltration into and less surface runoff from the NT treatment than for the other treatments. With greater water-bolding capacity, less surface runoff and more water infiltrating during rainfall events, and reduced evapotranspiration from under the mulch layer, as indicated by observed greater soil surface moisture contents, the NT treatment on this soil was beneficial to soil erosion protection and promoted increased crop production.