Quantifying the impact of 4R nutrient stewardship and cover cropping on soil health across the U.S. Cornbelt

Authors: CRESPO, CECILIA - Oak Ridge Institute For Science And Education (ORISE); BIRU, MOGES - University Of Florida; NUNES, MARCIO - University Of Florida; Kovar, John; Abendroth, Lori; BROUDER, SYLVIE - Purdue University; Carney, Derek; CHRISTIANSON, LAURA - University Of Illinois; DRURY, CRAIG - Agriculture And Agri-Food Canada; EAGLE, ALISON - Environmental Defense Fund; Emmett, Bryan; FERNÁNDEZ, FABIÁN - University Of Minnesota; GENTRY, LOWELL - University Of Illinois; HELMERS, MATT - Iowa State University; Malone, Robert; NELSON, KELLY - University Of Missouri; O'Brien, Peter; PREZA, FONTES - University Of Illinois; Rogovska, Natalia; Ruis, Sabrina; VOLENEC, JEFFREY - Purdue University

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2026
Publication Date: 7/11/2026
Citation: Crespo, C., Biru, M., Nunes, M., Kovar, J.L., Abendroth, L.J., Brouder, S.M., Carney, D., Christianson, L.E., Drury, C.F., Eagle, A.J., Emmett, B.D., Fernández, F.G., Gentry, L.E., Helmers, M.J., Malone, R.W., Nelson, K.A., O'Brien, P.L., Preza, F.G., Rogovska, N.P., Ruis, S.J., Volenec, J. 2026. Quantifying the impact of 4R nutrient stewardship and cover cropping on soil health across the U.S. Cornbelt. Soil and Tillage Research. https://doi.org/10.1016/j.still.2026.107366.
DOI: https://doi.org/10.1016/j.still.2026.107366

Interpretive Summary: The 4R (Right source, Right rate, Right time, Right place) nutrient stewardship framework is intended to increase crop production and farmer profitability while maintaining or enhancing the quality of soil and water resources. However, there is limited research evaluating the impact of 4R nutrient management on soil health across various locations in the U.S. Corn Belt. In this study, we utilized a network of seven coordinated studies within the major corn-producing region of the U.S. to measure and compare soil health in crop production fields with typical practices, such as conventionally tilled continuous corn or conventionally-tilled corn-soybean rotations, for the region, 4R nutrient management, and 4R nutrient management combined with cover crops. A comprehensive soil quality index (SQI), which integrates crop productivity, nutrient cycling, and environmental protection, was used to quantify soil health. Results showed that after four years of implementation, 4R practices only improved soil health indicators when combined with cover crops. These results highlight the importance of integrating conservation practices such as cover crops with the 4R practices to improve soil health in the short-term. These results will enable land managers, producers, and crop advisors to better understand how to improve soil health for sustainable crop production in the U.S. Corn Belt.

Technical Abstract: The adoption of the “4R” Nutrient Stewardship framework in crop production has been increasing over the last few decades. However, studies evaluating how these practices affect both agronomic outcomes and soil health across various environments in the U.S. Corn Belt are limited. With a network of coordinated studies in the major corn-producing region of the U.S., we evaluated the change in soil health indicators over four years of 4R management practices with and without a cover crop as compared to the prevailing practice used by farmers in the region, and/or a system without nitrogen (N) fertilization. Soil properties were determined in 2017 and 2020 at 0-15 cm depth. Eight soil indicators were individually scored using the Soil Management Assessment Framework (SMAF) curves and integrated into an overall Soil Quality Index (SQI). After 4 years of implementation, 4R practices only improved soil health indicators when combined with cover crops compared to 2017 (up to 16% increase in SQI). In contrast, the other treatments only led to small changes in SQI after 4 years. Changes in SQI were not correlated with corn yields. Over a 4-year timeframe, 4R management alone did not enhance soil health; however, the incorporation of conservation practices such as cover crops was beneficial for improvements in SQI in the short-term.