Using stimulated rainfall to evaluate cover crops and winter manure application to limit nutrient loss in runnoff

Authors: Bhandari, Ammar; GELDERMAN, RONALD - South Dakota State University; GERMAN, DAVID - South Dakota State University; Kharel, Tulsi

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2022
Publication Date: 2/1/2023
Citation: Bhandari, A.B., Gelderman, R., German, D., Kharel, T.P. 2023. Using stimulated rainfall to evaluate cover crops and winter manure application to limit nutrient loss in runnoff. Agrosystems, Geosciences & Environment. Volume6, Issue1. https://doi.org/10.1002/agg2.20348.
DOI: https://doi.org/10.1002/agg2.20348

Interpretive Summary: With winter manure application, management systems such as tillage and cover crops are important to address nutrient loss in surface runoff. Although winter manure application is not recommended, producers are still applying manure during winter due to the limited storage capacities in traditional concentrated animal feeding operations, lack of storage facilities in small farms, and more time available for manure application and spreading, and to avoid soil compaction. Improved understanding of coupling rye cover crops with winter manure injection on nutrient loss in the Northern Great Plains can help develop and support the strategic use of cover crops in winter manure management. Researchers from South Dakota State University and USDA-ARS Crop Production System Research Unit, Stoneville, MS, used data from a rain simulation study to analyze potential risk of nutrient and sediment loss in spring runoff with a significant stake in water quality and manure management. Results indicated that the use of winter cover crops helps to minimize nutrient and sediment loss from an agricultural field in spring runoff. Overall, cover crops reduced nutrient loss in concentration by 6 to 48% in the dry (first rainfall simulation) and 8 to 40% in the wet (second rainfall simulation) run than with no-cover crops. Manure application increased nutrient loss in concentration by 6 to 58% in the dry and 10 to 69% in the wet run than with no-manure. In addition, cover crops are more effective in reducing nutrient and sediment loss when manure is applied. Further, the results also indicated that even if manure was incorporated during winter, approximately six months before the rainfall events, it still poses a potential risk to surface water quality without cover crops. This research on using winter cover crops with manure will help producers and other stakeholders address the winter manure management and surface water quality issues in the Great Northern Plains of the Dakotas.

Technical Abstract: Cover crops can be effective in minimizing nutrient losses from agricultural fields. The objective of this study was to determine the impact of cover crop (rye, Secale strictum) with winter manure application on nutrient loss in simulated rainfall runoff. A split block design study with manure (manure vs. no manure) and cover crops (cover crops vs. no cover crops) was established in 2009. Two rain simulations (the first defined as ‘dry’ and the second ‘wet’) using sixteen 2 m2 steel frames were conducted in May 2010. The runoff volume collected from each plot were analyzed for nitrate-nitrogen (NO3-N), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total dissolved phosphorus (TDP). In the dry run, the concentration and load of NO3-N was significantly lower (p=0.05) in runoff with the cover crop than in no-cover crop treatments. Overall, cover crops reduced nutrient loss in concentration by 6 to 48% in the dry and 8 to 40% in the wet run than with no-cover crops. The concentration and load of NO3-N were significantly higher under manure treatments in both “dry” and “wet” runoff runs compared to no manure application. Manure application increased nutrient loss in concentration by 6 to 58% in the dry and 10 to 69% in the wet run than with no-manure. This study helps understand the complexity of winter manure application with cover crops and potential risks of nutrient and to surface runoff during spring in the Northern Great plains of the Dakotas.