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Submitted to: International Soil and Water Conservation Research
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/31/2018 Publication Date: 8/29/2018 Citation: Gonzalez, J.M. 2018. Runoff and losses of nutrients and herbicides under long-term conservation practices (no-till and crop rotation) in the U.S. Midwest: A variable intensity simulated rainfall approach. International Soil and Water Conservation Research. 6(4)265-274. doi.org/10.1016/j.iswcr.2018.07.005. DOI: https://doi.org/10.1016/j.iswcr.2018.07.005 Interpretive Summary: The U.S. Farm Bill includes conservation practices that benefit both the environment and the farmer. The USDA Conservation Effects Assessment Project is a multi-agency effort to assess the efficiency of conservation practices to minimize non-point source pollution. The long-term effects of tillage and crop rotation on soil properties, discharge, surface runoff and losses of sediments, ammonium, nitrate, soluble reactive P (SRP), atrazine, and glyphosate were investigated using rainfall simulations in corn-planted plots with corn and soybean residues under no-till and chisel tillage systems. Soil carbon and nitrogen, water infiltration, and water content were higher under long-term no-till, compared to chisel tillage. Furthermore, the positive influence of long-term no-till, relative to chisel tillage, were observed on runoff and losses of sediments, ammonium, and nitrate; however, tillage did not affect losses of SRP, atrazine, and glyphosate. Conversely, corn residue reduced the losses of ammonium, atrazine, and glyphosate, relative to the soybean residue, but nitrate and SRP losses were not affected. The results of this study suggest that additional conservation practices, in conjunction with no-till and crop rotation are needed to reduce surface losses of nutrients and pesticides. Such conservation practices may include grassed waterways and/or filters at the edge of the fields, blind inlets in closed depressions, and the use of adjuvants that adhere to crop residue. Technical Abstract: The U.S. Farm Bill includes conservation practices that benefit both the environment and the farmer. The USDA Conservation Effects Assessment Project (CEAP) is a multi-agency effort to assess the efficiency of conservation practices to minimize non-point source pollution. This is follow-up study of a long-term experiment design to assess the influence of tillage and crop residue on soil health and water quality. In this study, the long-term effects of tillage and crop rotation on soil properties, discharge, surface runoff and losses of sediments, ammonium-N, nitrate-N, soluble reactive P (SRP), atrazine, and glyphosate were investigated using rainfall simulations in corn (Zea mays L.)-planted plots with corn and soybean (Glycine max [L] Merr.) residues under no-till and chisel tillage systems. Soil C and N content, infiltration, and water content were higher under the long-term no-till, compared to chisel tillage. Furthermore, the positive impact of long-term no-till, relative to chisel tillage, was observed on surface discharge and losses of sediments, ammonium-N, and nitrate-N; however, there was no tillage effect on runoff of SRP, atrazine, and glyphosate. Conversely, corn residue reduced the losses of ammonium-N, atrazine, and glyphosate, relative to the soybean residue, but nitrate-N and SRP losses were not affected. The results of this study suggest that additional conservation practices, in conjunction with no-till and crop rotation are needed to reduce surface losses of nutrients and pesticides while improving soil health. Such conservation practices may include grassed waterways and/or filters at the edge of the fields, blind inlets in closed depressions, and the use of adjuvants that adhere to crop residue. |
