Cover crops and nitrogen scavenging

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.

For more information or to help decide what cover crop will be best for your farm contact Michigan State University Extension educators Christina Curell, .(JavaScript must be enabled to view this email address) or Paul Gross, .(JavaScript must be enabled to view this email address). More information can also be found at the Midwest Cover Council website.

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