Non-legume cover crops can be crucial for trapping nitrogen in a field and preventing loss. When left fallow, nitrate can move out of the root zone and field through tile drainage and groundwater. Non-legume cover crops will take up nitrogen during their growth and return it to the soil when it decomposes. This practice can extend the time a nitrogen input is in the field and improve the return on investment.
Species Selection
Grasses and brassicas are typically planted for nitrogen scavenging. Their growth and biomass will influence the amount of nitrogen they can trap.Common Cover Crop Species for Nitrogen Scavenging
- Winter Cereal Rye
- Winter Triticale
- Barley
- Oats
- Radish
Considerations
Cover crops can scavenge residual nitrogen left in the soil after the cash crop harvest. They will also trap any fall manure or nutrient applications and hold them in the field for next year's crop. This practice can also improve cover crop growth and biomass, which may enhance other benefits.It is important to remember that nitrogen scavenging is not the same as nitrogen fixation. These cover crops do not add additional nitrogen but help prevent the loss of costly nitrogen inputs from a farmer's field.References
- Natural Resources Conservation Service. (2019). Cover Crops and Prevented Planting. U.S. Department of Agriculture. https://www.farmers.gov/sites/default/files/documents/Prevented%20Planting%20and%20Cover%20Crops%20fact%20sheet%20-%2007022019.pdf#:~:text=Cover%20crops%2C%20including%20annual%20grasses%20and%20brassicas%2C%20can,a%20higher%20total%20nutrient%20availability%20for%20subsequent%20crops.
- O’Dea, J. K. & Cornell Cooperative Extension of Ulster County. (n.d.). How are Cover Crops Affecting my Nutrient Levels?: Understanding cover crop qualities and strategies for efficient nutrient management. Cornell Cooperative Extension. http://www.hort.cornell.edu/expo/proceedings/2016/Soil%20Health%20HOW%20ARE%20COVER%20CROPS%20AFFECTING%20MY%20NUTRIENT%20LEVELS%20ODea.pdf
- Precision Sustainable Agriculture. Cover Crop Selector. https://covercrop-selector.org/
