By Christina Curell, Michigan State University Extension
Cover crops can be used to scavenge for excess Nitrogen. The following chart rates cover crops ability to scavenge nitrogen
The reasons why farmers use cover crops are as varied as the number of species that can be used as a cover crop. Traditionally cover crops were used for erosion control but in the past few years’ cover crops have been used for other purposes.
Nitrogen is necessary for all plant growth. When added to the soil nitrogen if not taken up by the plants can move readily through the soil profile. In the worst case scenario nitrogen will leach through the soil and get into groundwater. One of the ways that farmers can reduce the chances of nitrogen leaching is to add a cover crop that will scavenge nitrogen and hold it in its plant tissue. Once these covers breakdown the nitrogen will be released and used by the subsequent crop. Remember, however, that it will take time for the plant to decompose so nitrogen will not be readily available in the spring.
The following chart rates typical cover crops grown in Michigan for its nitrogen scavenging tendencies. Do not confuse nitrogen scavenging for nitrogen fixing. These are different concepts that will be addressed and I will address them in a subsequent article.
Excellent | Very Good | Good | Fair |
Cereal Rye | Annual Ryegrass | Mustards | Field Pea |
Sorghum-Sudan | Barley | Crimson Clover | Hairy Vetch |
Radish | Oats | Red Clover | Sweetclovers |
| | Wheat | | White clover |
| | Rapeseed | | |
| | Berseem Clover | | |
Chart information taken from Managing Cover Crops Profitably third edition, SARE Handbook Series 9.