HISTORY, RESIDUE, AND TILLAGE EFFECTS ON EROSION OF LOESSIAL SOIL

Abstract

Studies have shown that no-till (NT) management reduces soil erosion relative to chisel/disk-tillage (CT) and thatthis benefit may increase over time. There are fewer data, however, to separate the erosion-reduction contributions of surfaceresidue mulch from those of improved soil properties under NT. The objective of this study was to quantify these separate contributionsfor a silt loam soil (Glossic Fragiudalf) used for corn (Zea mays L.) production in northern Mississippi for five toten years with either CT or NT. The experiment had ten treatments. Two were normal CT and NT managements in which acrop was planted but had not emerged prior to simulated rainfall. The other eight treatments had surface crop residuesremoved and comprised a 2 2 2 factorial arrangement of two tillage histories (CTh or NTh), two levels of tillageimmediately prior to rainfall simulation (disturbed or not disturbed), and two levels of residue removal (residue removed justprior to simulated rainfall or residue removed one year prior to simulated rainfall). Simulated rainfall was applied at a rateof 65 mm h-1 in a three-storm sequence on 10.7 3.7 m areas. NT exhibited greater runoff but much lower sediment lossesthan CT. Residue removal doubled erosion for both tillage histories. Surface disturbance decreased runoff from the first stormfollowing tillage but increased total soil loss 26% to 47%. With residues removed, long-term NTh resulted in one-third thesoil loss of CTh, and similar benefits were observed with or without surface disturbance. This residual benefit of NTh waslost within one year of fallow after residue removal. These results demonstrate that the erosion resistance of NT areas is dueto both residue cover and improved soil quality factors. Although the erosion-resisting soil quality factors developed overseveral years of NT management may be lost within a single year of fallow management, these factors may protect the soilfrom excessive erosion if NT fields that must occasionally be tilled are quickly returned to NT management.