Potential for nutrient loss reduction in cover cropped systems in the Upper Midwest

Authors: Weyers, Sharon; THOM, MATTHEW - UNIVERSITY OF MINNESOTA; FORCELLA, FRANK; EBERLE, CARRIE - UNIVERSITY OF WYOMING; MATTHEES, HEATHER - LAND O'LAKES, INC.; Gesch, Russell - Russ; OTT, MATTHEW - UNIVERSITY OF MINNESOTA; Feyereisen, Gary; STROCK, JEFFREY - UNIVERSITY OF MINNESOTA; WYSE, DONALD - UNIVERSITY OF MINNESOTA

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2019
Publication Date: 4/4/2019
Publication URL: https://handle.nal.usda.gov/10113/6659754
Citation: Weyers, S.L., Thom, M.D., Forcella, F., Eberle, C.A., Matthees, H.L., Gesch, R.W., Ott, M., Feyereisen, G.W., Strock, J.S., Wyse, D. 2019. Potential for nutrient loss reduction in cover cropped systems in the Upper Midwest. Journal of Environmental Quality. 48(3):660-669. https://doi.org/10.2134/jeq2018.09.0350.
DOI: https://doi.org/10.2134/jeq2018.09.0350

Interpretive Summary: Winter cover crop systems help reduce nutrient loss through wind and water erosion. However, establishing cover crop systems in the Upper Midwest is challenging due to lack of winter-hardy crop varieties and incentives for adoption. Research conducted at Morris, MN, evaluated the ability of novel over-wintering oilseed crops, winter camelina and pennycress to sequester soil N and potentially reduce nutrient loss from soybean production systems. Winter-surviving oilseed crops sequestered available N while reducing soil water nitrate from fall through spring soybean planting. These novel winter cropping systems can provide much needed mechanisms to reduce potential nutrient loss, but also can be harvested which provides an economic incentive for their adoption. These results will help researchers, land managers and policy makers to develop, support and promote cover cropping strategies that provide both environmental and economic benefits.

Technical Abstract: Over-wintering crops reduce nutrients in soil leachate in spring, but little economic incentive is available to grow these crops in the Upper Midwest. New oilseed-bearing cash cover crops, such as winter camelina and pennycress, may provide needed incentives. However, the abilities of these crops to sequester labile soil nutrients are unknown. To address this unknown, soil water NO3-N and soluble reactive phosphorus (SRP) (sampled with lysimeters placed at 30, 60, and 100 cm) were measured in cover cropped or winter-fallowed soybean (Glycine max L.) cropping systems over two growing seasons. Cover crops, including forage radish (Raphanus sativus L.), winter rye (Secale cereal L.), field pennycress (Thlaspi arvense L.), and winter camelina (Camelina sativa L.), were compared to chisel till and no-till fallow systems. Pennycress and winter camelina were harvested at maturity after relay sowing of soybean. Winter rye and radish sequestered more N in autumn biomass, ranging 26 to 38 kg N ha-1, but over-wintering oilseeds matched or exceeded N-uptake in spring, ranging 28 to 49 kg N ha-1 before soybean planting. Biomass N uptake was reflected by reductions in soil water NO3-N during cover crop and intercropping phases for all cover treatments, averaging 4 mg L-1, compared to fallow treatments, which averaged 31 mg L-1. In general, cash cover crops like pennycress and winter camelina provide both environmental and economic resources to growers in that they represent cash-generating grain crops that sequester labile soil nutrients, especially in spring, and protect and promote soil health from autumn through early summer.