Runoff and nutrient losses in extended and conventional crop rotations

Authors: Logsdon, Sally; O'Brien, Peter

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2022
Publication Date: 11/23/2022
Citation: Logsdon, S.D., O'Brien, P.L. 2022. Runoff and nutrient losses in extended and conventional crop rotations. Agrosystems, Geosciences & Environment. 5(4). Article 20318. https://doi.org/10.1002/agg2.20318.
DOI: https://doi.org/10.1002/agg2.20318

Interpretive Summary: Corn and soybean are the most common crops grown in the Midwestern United States, but they grow only during certain months of the year. Because plants are not growing for long periods of time the soil can be uncovered for lengthy periods of time. Heavy rainfall on bare soils can result in water lost through runoff and soil and nutrients lost through erosion. Some ways to protect the soil include less soil tillage, more crop residue being left on the soil, and longer crop rotations including the use of perennial crops which continue growing beyond one season, in addition to the production of corn and soybeans. These strategies are effective in reducing soil and nutrient runoff when perennial crops are growing, but they do not continue to work during the corn and soybean years of the extended crop rotation. Using a rainfall simulator, it was shown that a field which included perennial crops, lost less water as runoff compared to a field that grew only corn and soybeans every year. However, there were no differences in soil erosion or nutrient losses. Overall, the benefits of the seven-year crop rotation were caused by less soil tillage and more ground cover rather than the including different crops. This information is important for scientists, crop advisors, conservation professionals, policy makers, and farmers that are trying to find ways to have high crop production under new weather conditions caused by climate change.

Technical Abstract: Management systems prioritizing surface ground cover throughout the year, such as extended crop rotations with perennial phases or reduced tillage, may be more resilient to changing precipitation regimes associated with climate change. The purpose of this study was to determine if the benefits of perennials for reducing runoff and erosion persisted in the annual crop phases for infiltration, runoff, and sediment and nutrient losses. Experimentation using rainfall simulations at four landscape positions in a seven-year rotation with ridge-tillage and in a conventional corn-soybean system were evaluated. Using data paired by landscape position across four years, the seven-year rotation had significantly less runoff than the conventional field, though infiltration and sediment losses were similar. Overall, runoff was correlated with ground cover, indicating that tillage practices and residue removal had a greater influence than any indirect effects of the extended rotation.