Cover Crops Can Be Used to Prevent Nitrogen Loss

By Sarah Fronczak

Updated from an original article written by Christina Curell, Michigan State University Extension.

Careful manure management is a principle of farm profitability and environmental stewardship. Livestock farmers are looking for ways to reduce the incidence of nitrogen leaching into groundwater from manure. Farmers have adapted and changed their practices to address timing of applications and application methods. Applying manure to land that has a cover crop is another practice that can help with nitrogen management.

The Michigan State University Extension field crops team is releasing two short videos, on solid and liquid manure. These videos are part of a series highlighting cover crops use with manure management. MSU Cover Crop & Soil Health Team YouTube channel will host the recordings.

Minnesota researchers, led by Dr. Les Everett, University of Minnesota Water Resource Center, wanted to determine:

1. Fate of nitrogen in the soil from injected manure with and without a cover crop
2. Nitrogen needs to the cash crop with and without cover crops are met

Winter cereal rye was planted following corn silage or soybeans during the 2016 and 2017 growing season on 19 farms in central and southern Minnesota. Dairy or swine manure was injected in the 3 replicated plots with a check strip after the rye was established. In the spring, cover crop biomass, nitrogen content of the cover crop, and soil nitrate was checked. Rye was terminated and in most cased incorporated into the field. The fields were then planted with corn and a starter fertilizer was applied during planting. Corn yield and nitrogen content were determined during harvest.

The research resulted in the following findings:

1. In both years, adequate growing season existed to establish the rye cover crop after either corn silage or soybean harvest, but above-ground fall growth was limited.
2. The rye was very resilient to manure injection, however, stand reduction was considerable at two sites where shank injectors or disk coverers were too aggressive.
3. At most sites, the spring rye growth did well with soil nitrate reduced under the cover crop. Compared to the check strips of all sites.
4. Rye growth and nitrogen uptake were greater in southern Minnesota rather than central Minnesota.
5. Across sites, there was not a significant difference in silage or grain yield between the cover crop and check strips.

Future research is required to assess the effects of cover crop termination methods and timing on nitrogen dynamics and performance of the subsequent corn crop. To obtain the full research report visit this link.

Adoption of a cover crop management scheme allows for a responsive cover in the event of sudden thaws that characterize winter in Michigan. Cover crops proved to be effective in reducing NO3-N loading through tile-drainage across the spectrum of common nitrogen fertilizer management systems.