Cropping System Diversity Effects on Nutrient Discharge, Soil Erosion, and Agronomic Performance

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Hunt, Natalie D.
Hill, Jason D.
Liebman, Matt
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© 2019 American Chemical Society
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The Department of Agronomy seeks to teach the study of the farm-field, its crops, and its science and management. It originally consisted of three sub-departments to do this: Soils, Farm-Crops, and Agricultural Engineering (which became its own department in 1907). Today, the department teaches crop sciences and breeding, soil sciences, meteorology, agroecology, and biotechnology.

The Department of Agronomy was formed in 1902. From 1917 to 1935 it was known as the Department of Farm Crops and Soils.

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  • Department of Farm Crops and Soils (1917–1935)

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Iowa Nutrient Research Center
The Iowa Nutrient Research Center was established to pursue science-based approaches to evaluating the performance of current and emerging nutrient management practices and providing recommendations on practice implementation and development. Publications in this digital repository are products of INRC-funded research. The INRC is headquartered at Iowa State University and operates in collaboration with the University of Iowa and the University of Northern Iowa. Additional project information is available at:
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Nutrient, herbicide, and sediment loading from agricultural fields cause environmental and economic damage. Nutrient leaching and runoff pollution can lead to eutrophication and impaired drinking water resources, while soil erosion reduces water quality and agronomic productivity. Increased cropping system diversification has been proposed to address these problems. We used the ArcSWAT model and long-term Iowa field experimental measurements to estimate eutrophication and erosion impacts of three crop rotation systems under two weed management regimes. Rotations were comprised of 2-year corn–soybean, 3-year corn–soybean–oat/clover, and 4-year corn–soybean–oat/alfalfa–alfalfa systems. All were managed with conventional or low herbicide applications. Total N and P runoff losses were up to 39% and 30% lower, respectively, in the more diverse systems than the 2-year corn–soybean system, but NO3–-N leaching losses were unaffected by cropping system. Diversification reduced erosion losses up to 60%. The 3- and 4-year systems maintained or increased crop yields and net returns relative to the 2-year conventional system. Reductions in herbicide use intensity generally did not affect nutrient and sediment losses nor crop yields and profitability. These results indicate that diversifying the corn–soybean rotation that dominates the central United States could reduce water nutrient contamination and soil erosion while maintaining farm productivity and profitability.
This article is published as Hunt, Natalie D., Jason D. Hill, and Matt Liebman. "Cropping system diversity effects on nutrient discharge, soil erosion, and agronomic performance." Environmental science & technology 53, no. 3 (2019): 1344-1352. doi:10.1021/acs.est.8b02193. Posted with permission of INRC.