Cover crops can be used to prevent nitrogen loss
Cover crop research shows that winter cereal rye may reduce nitrate leaching
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 things such as manure, timing of applications and application methods. Another practice that we see increasing in Michigan is applying manure to land that has a cover crop. Does adding the expense of a planting a cover crop and terminating a cover crop make economic and environmental sense?
Minnesota researchers, led by Dr. Les Everman, University of Minnesota Water Resource Center retired, wanted to determine:
- Fate of nitrogen in the soil from injected manure with and without a cover crop
- 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 2015 and 2016 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 were checked (see figure 1). Rye was terminated and in most cased incorporated into the field. The fields were then planted with corn and a starter fertilizer was applied at planting. Corn yield and nitrogen content were determined at harvest (see figures 2 and 3).
The research resulted in the following findings:
- In both years, adequate growing season existed to establish the rye cover crop after either corn silage or soybean harvest, but aboveground fall growth was limited.
- 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.
- Spring rye growth was good at most sites with soil nitrate reduced under the cover crop compared to the check strips at all sites.
- Rye growth and nitrogen uptake were greater in southern than central Minnesota.
- Across sites, there was no significant difference in silage or grain yield between the cover crop and check strips.
To obtain the full research report visit http://soilhealthnexus.org/effects-liquid-manure-injection-winter-rye-cover-crop-farm-trials/.
If you would like to learn more about cover crops, how they can benefit your farm, or to find a cover crop educator visit the Michigan State University Extension Cover Crop site.