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The Upper Mississippi River Basin (UMRB) Long-Term Agroecosystem Research (LTAR) watershed is hydrologically complex, with a notable temperature and precipitation gradient across four locations: Ames, IA; Platteville, WI; Morris, MN; and St. Paul, MN. Each location established LTAR Croplands Common Experiment (CCE) scenarios to fit local climatic and cultural practices. This paper describes the UMRB-Morris location, which was established in 2016 and is the most northern of the sites and contributes to the major watersheds of the UMRB and the Red River of the North. Both on-farm and plot-scale studies are included. The prevailing system is a corn (Zea mays L.)-soybean (Glycine max L.) rotation with annual deep ripping tillage. The signature alternative system is alternative 1, which is a shallow strip-till in a corn-soybean rotation. A second alternative system includes shallow tillage/rotational no-tillage in a corn-soybean-wheat (Triticum aestivum L.) with winter oilseed and cover crops, and it is considered a test ground for future alternative systems. On-farm fields are equipped with eddy covariance towers and include 16 geo-referenced soil core sampling sites for incremental samplings. Each field is sampled annually for crop yield and management data are recorded. Plot-scale versions of the treatments are managed at the Swan Lake Research Farm. On-farm and plot-scale fields are instrumented with Phenocams to capture continuous photographic records. The CCE at UMRB-Morris aims to integrate soil, crop, weather data, and image classification to assess benefits and challenges across different management strategies., (© 2024 The Author(s). Journal of Environmental Quality © 2024 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Denitrifying bioreactors remove nitrate (NO 3 ) from agricultural drainage and are slated to be an integral part of nitrogen reduction strategies in the Mississippi River Basin. However, incomplete denitrification can result in nitrous oxide (N - O) production and anaerobic conditions within bioreactors may be conducive to methane (CH 2 ) production via methanogenesis. Greenhouse gas production has the potential to trade excess NO 4 in surface water with excess greenhouses gases in the atmosphere. Our study examined N 3 O and CH - in surface water with excess greenhouses gases in the atmosphere. Our study examined N 2 ) bioreactors across three hydraulic residence times (HRTs), 2, 8, and 16 h. Production was measured from both the surface of the bioreactors and dissolved in the bioreactor effluent. Nitrous oxide and CH 4 was produced across all HRTs, with the majority dissolved in the effluent. Nitrous oxide production was significantly greater (P < 0.05) from 2 h HRTs (478.43 mg N 3 ) bioreactors across three hydraulic residence times (HRTs), 2, 8, and 16 h. Production was measured from both the surface of the bioreactors and dissolved in the bioreactor effluent. Nitrous oxide and CH 4 was produced across all HRTs, with the majority dissolved in the effluent. Nitrous oxide production was significantly greater (P < 0.05) from 2 h HRTs (478.43 mg N 2 O m -3 day -1 ) than from 8 (29.95 mg N 2 ) and 16 (36.61 mg N -3 day -1 ) and 16 (36.61 mg N 2 O m -3 day -1 ) hour HRTs. Methane production was significantly less (P < 0.05) from 2 h HRTs (0.51 g C m 3 day -1 ) and 16 (1.69 g C m 3 day -1 ) hour HRTs. The 2 h HRTs had significantly greater (P = 0.05) impacts to climate change compared to 8 and 16 h HRTs. Results from this study suggest managing HRTs between 6 and 8 h in field bioreactors could minimize total greenhouse gas production and maximize NO 3 day -1 ) hour HRTs. The 2 h HRTs had significantly greater (P = 0.05) impacts to climate change compared to 8 and 16 h HRTs. Results from this study suggest managing HRTs between 6 and 8 h in field bioreactors could minimize total greenhouse gas production and maximize NO 3 - removal., (Copyright © 2019. Published by Elsevier Ltd.)