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Title: SOYBEAN YIELD RESPONSE TO TILLAGE AND LANDSCAPE POSITION

Author
item JOHNSON, J
item McGregor, Keith
item Cullum, Robert

Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 6/23/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Crop productivity is slowly lost over time from soil erosion on most Southeastern U. S. fields. Reduction of crop yields from different landscape positions may not be recognized until the land is no longer suitable for growing crops. Soybean yields from four no-till plots and four conventional-till plots, within a larger on- going study, were extended to include the effects of slope position on erosion. Fragipan depths within each landscape position varied from about 12 to 18 inches. Row lengths of the 150 feet long plots were divided into 25 feet increments downslope. Slope position influenced soybean yields in 9 of 13 years. After seven years of continuous tillage systems, yields were severely impacted in the 75 to 125 ft range of conventional-till plots each year. Yields in the range of 125 to 175 ft down slope were not impacted in the conventional-till plots. Apparently, sedimentation was taking place in this area of the lower slope. Yields in the no-till areas were not as affected by slope position as in the conventional-till plots, which indicated more soil stability along the slope in no-till plots where erosion was not taking place. These results will be useful to farmers and to extension and conservation action agencies.

Technical Abstract: This report expands on an earlier study of the effects of long-term erosion on 12 paired no-till and conventional-till soybean plots. Analysis of four paired plots within the larger on-going study was extended to include the effects of slope position on erosion. During 1984 to 1996, no-till soybean was grown on one plot (150 feet in length) of each pair and conventional till soybean was grown on the other plot. Depth to a fragipan layer varied from about 12 to 18 inches. Row lengths were divided into 25 feet increments downslope. No-till soybean gave higher yields in 11 of 13 years in the four selected paired plots as compared to conventional-till soybean. Slope position influenced soybean yields in 9 of 13 years. After seven years of continuous tillage systems, yields thereafter were severely impacted from 75 to 125 feet downslope in the conventional-till plots. Yields from 125 to 175 feet downslope were not affected in the conventional ltill plots. Apparently, sedimentation was taking place in this area of the lower slope. Yields in the no-till areas were not influenced as much by slope position as in the conventional-till plots, which indicated more soil stability along the slope in no-till plots where erosion was not taking place. These results will be useful to farmers and to extension and conservation action agencies.