USDA LTAR network research: Upper Mississippi River Basin – St. Paul, MN

Authors: Dalzell, Brent; Baker, John; Venterea, Rodney - Rod; Spokas, Kurt; Feyereisen, Gary; Rice, Pamela; Alexander, Jonathan

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2024
Publication Date: 9/10/2024
Citation: Dalzell, B.J., Baker, J.M., Venterea, R.T., Spokas, K.A., Feyereisen, G.W., Rice, P.J., Alexander, J.R. 2024. USDA LTAR network research: Upper Mississippi River Basin – St. Paul, MN. Journal of Environmental Quality. https://doi.org/10.1002/jeq2.20615.
DOI: https://doi.org/10.1002/jeq2.20615

Interpretive Summary: The USDA-ARS Soil and Water Management Research Unit in St. Paul, MN, is conducting long-term research integrating kura clover into the typical corn-soybean rotation of the Midwest. The aim is to understand the environmental and agronomic impacts of this conservation practice. Benefits of kura clover living mulch include improved soil quality and reduced nitrogen leaching, but there are challenges like potential nitrous oxide emissions and reduced yields in droughts. Ongoing research aims to find solutions to these challenges and engage stakeholders for practical implementation.

Technical Abstract: The Soil and Water Management Research Unit of the USDA-Agricultural Research Service is located in St. Paul, Minnesota and conducts long-term research at the University of Minnesota Research and Outreach Center located at Rosemount, MN. As part of USDA’s Long Term Agroecosystem Research (LTAR) network, the cropland common experiment (CCE) at this location is focused on integration of a kura clover (Trifolium ambiguum M. Bieb.) living mulch (KCLM) system into the prevailing two-year rotation of corn (Zea mays L.) and soybean (Glycine max L.) that is typical of the midwestern corn belt. The LTAR-CCE conducted at Rosemount, MN aims to compare the long term environmental and agronomic performance of KCLM while identifying challenges and developing management strategies for this alternative practice. The use of a living mulch for this region is advantageous because, once established, it does not require additional time for fall field operations typically associated with winter cover crops. Results from LTAR-CCE studies at this site show that KCLM results in a substantial increase in soil field-saturated hydraulic conductivity and decreases in leaching of nitrate-nitrogen (NO3--N). Disadvantages of the KCLM system include potential for increased emissions of nitrous oxide (N2O) and reduced crop yields, particularly during drought. Also, the optimal approach for crop row establishment in the spring remains uncertain. Ongoing LTAR-CCE research with KCLM aims to better understand and quantify both benefits and risks across conditions of interannual weather variability and changing climate to develop guidance for suitable adoption and management of this alternative practice.