EFFECTS OF TILLAGE AND RESIDUE MANAGEMENT ON RUNOFF AND EROSION

Authors: Wilson, Glenn; McGregor, Keith; Dabney, Seth

Submitted to: Mississippi Water Resources Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/22/2002
Publication Date: 9/24/2002
Citation: Wilson, G.V., Mcgregor, K.C., Dabney, S.M. 2002. Effects of tillage and residue management on runoff and erosion. Eagle Ridge Conference. Mississippi Water Resources Research Conference Proceedings. 164-175.

Interpretive Summary: Information is needed on how residue contributes to erosion control and more information is needed on the impacts of converting no-till management systems (NT) into conventional-till (CT) systems and CT systems converted into NT systems. The objective of this study was to use plots at the Nelson Farm in north Mississippi to determine the effects of residue management and tillage practices on runoff and erosion. Plots with a long-term history as CT and long-term history as NT were used. Some were maintained in CT and NT while others had their tillage systems switched to evaluate the effect of converting the tillage system. Some of the plots had residue from the previous years crop left on the surface and others had the residue removed to mimic poor residue management. Plots had an average slope of 5.6% on a Grenada silt loam (Glossic Fragiudalf) soil. Rainfall was applied to a 3.7 m by 10.7 m area within plots at a rate of 65 mm/h for one hour under natural soil moisture conditions called a dry run, followed by a 30 minute simulation four hours later called a wet run, and another 30 minute application 30 minutes later (very wet run). NT systems exhibited greater runoff than CT systems, however, sediment losses were greater for CT. Initial response to residue removal was an increase in runoff and erosion for both systems. The second year of residue removal did not affect runoff but caused substantially higher sediment losses particularly for plots with a history of NT. This carry-over effect resulted in NT systems having similar erosion rates as CT systems by the subsequent year of residue removal. This work demonstrates that good residue management can be more important than the tillage system for erosion control.

Technical Abstract: Numerous studies have shown the benefits of no-till (NT) cropping systems at reducing erosion. Quantitative information is needed on how residue contributes to erosion control. More information is also needed on the carry-over of benefits when NT systems are converted back to conventional-till (CT) systems. The objective of this study was to use long-term CT and NT plots at the Nelson Farm in north Mississippi to elucidate the effects of residue management and tillage practices on runoff and erosion. Rainfall simulations were conducted on 13 plots in year 1 and 11 plots in year two. Plots were managed to obtain the following treatments: CT history maintained in CT with residue left on the surface, CT history maintained in CT with residue removed from the surface, CT history converted to NT with residue removed from the surface, NT history maintained in NT with residue left on the surface, NT history maintained in NT with residue removed from the surface, and NT history converted to CT with residue removed from on the surface. Plots had an average slope of 5.6% on a Grenada silt loam (Glossic Fragiudalf) soil. Rainfall was applied to a 3.7 m by 10.7 m area within plots at a rate of 65 mm/h for one hour under natural antecedent soil-water conditions (dry run), followed by a 0.5 h simulation four hours later (wet run), and another 0.5 h application 30 minutes later (very wet run). Runoff and soil loss were adjusted for variations in rainfall to the prescribed application rate and soil loss was further adjusted for difference in slope among plots. NT systems exhibited greater runoff than CT systems, however, sediment losses were greater for CT. Initial response to residue removal was an increase in runoff and erosion for both systems. The second year of residue removal did not affect runoff but caused substantially higher sediment losses particularly for plots with a history of NT. This carry-over effect resulted in NT systems having similar erosion rates as CT systems by the subsequent year of residue removal. This work demonstrates that residue management can be more important than the tillage system for erosion control.