CROP AND TILLAGE ROTATIONS - GRAIN-YIELD, RESIDUE COVER, AND SOIL-WATER

Information regarding crop yield response for different tillage and rotation systems is needed to determine regional or local suitability for a given production system. Our objective was to determine the effects of continuous and alternating tillage sequences in corn (Zea mays L.) monoculture and corn-soybean [Glycine max (L.) Merr.] rotation on residue cover, soil water, and grain yield. Continuous conventional tillage (CT), continuous no-tillage (NT), or CT and NT alternating every other year were evaluated during a 5-yr period on a Rion (fine-loamy, mixed, thermic Typic Hapludult)-Pacolet (clayey, kaolinitic, thermic Typic Kanhapludult) sandy clay loam complex at a Piedmont location and an Eunola sandy loam (fine-loamy, siliceous, thermic Aquic Hapludult) at a Coastal Plain location. The 5-yr average NT corn grain yield was 27% (1.15 Mg ha-1) higher than CT at the Piedmont location, but only 4% (0.32 Mg ha-1) higher at the Coastal Plain location. Continuous Nt at the Piedmont location also resulted in higher corn yields 2 out of 4 yr compared with NT following CT. The increase in corn yield with NT was associated with greater soil water availability, primarily attributed to surface residue cover from corn stover fostering greater infiltration on a crust-prone soil. Soybean yield during the 5-yr period was 5% higher with NT at the Piedmont location and unaffected by tillage at the Coastal Plain location. In general, crop rotation had no effect on corn yield at either location. Results indicate that continuous NT should be the system of choice on this upland Piedmont soil.