Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2011
Publication Date: 12/27/2011
Citation: Cullum, R.F. 2012. Influence of tillage on maize yield in soil with shallow fragipan. Soil and Tillage Research. 119:1-6.
Interpretive Summary: Success of maintaining good production of corn grown annually on sloping land with a shallow water restrictive layer is based on the assumption that the tillage management can aid in conserving soil and soil moisture and controlling weeds. A genuine concern for landowners and other stake holders is whether conservation tillage contaminates shallow groundwater even though it greatly reduces erosion. The study showed conservation tillage while maintaining good yields did not significantly increase chemical contamination of the shallow groundwater. Conservation tillage had slightly higher herbicide levels in the first runoff event of the growing season as compared to conventional tillage. The research points to using pre-emergence rotating herbicides and post-emergence Roundup in resistant corn to effectively control weeds in conservation tillage systems. Some form of conservation tillage that decreases or prevents erosion will be required on sloping lands with shallow fragipan to sustain long term continuous corn production. Information from this study provides the NRCS and extension personnel with additional guidance for making tillage and pesticide management recommendations to farmers.
Technical Abstract: A six-year continuous corn study was conducted that compared corn yields from no-tillage (NT), reduced-tillage (RT), and conventional-tillage (CT) on 4 to 6% sloping soils overlying a shallow fragipan. The objective was to test the hypothesis that no-tillage and reduced tillage has a different effect than conventional-tillage on corn produced on soils with a shallow water restricted layer. The study showed conservation tillage had minor detrimental effects on the water quality in runoff and shallow groundwater and promoted more soil water for crop use during the growing season than conventional tillage. With adequate weed control, NT produced higher yields than CT on these Loring soils due to soil moisture conservation. However, inadequate weed control occurred in several years of the study along with above normal rain resulting in lower NT corn yields as compared to CT yields. Significant differences in corn yield were found for type of tillage, year, and tillage-year interaction. These differences were explained by a tillage system’s ability to conserve soil moisture and control weeds. Other results included low sediment amounts lost from NT corn plots and insignificant free water quantities at the fragipan’s surface during the cropping season for all tillage systems. Maximum groundwater movement across the surface of the fragipan occurred during the non-cropping season under soil profile saturation. Amount, timing, and distribution of rainfall rather than tillage system primarily influenced agrichemical movement from corn systems in this study.