Cover crops as nitrogen source

Learn how cover crops can produce Nitrogen for your fields.

Cover Crops can be used to produce Nitrogen. The following charts rates legumes as a nitrogen source and gives nitrogen production from common cover crop species.

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. Legumes have the ability to “fix” nitrogen from the air and store it in nodules in their roots. This nitrogen can be released or use by subsequent crops.

The following chart rates typical legume cover crops grown in Michigan for its nitrogen fixation 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

Berseem Clover

Crimson Clover

 

Cowpea

Red Clover

Field Pea

 

Hairy Vetch

 

Sweet Clover

White Clover

Chart information taken from Managing Cover Crops Profitably third edition, SARE Handbook Series 9.

            There have been many research studies conducted to determine how much nitrogen cover crops produce. There are many factors that determine how much nitrogen can be credited to cover crop. For that reason a large range for nitrogen credit is given, see chart below. It is very important to take a good soil sample if you plan to use cover crops as a nitrogen source. It is also advisable to follow up with a plant tissue analysis to ensure that you have enough nitrogen for production.        

Cover Crop

Lb./A *

Mustard

30-120

Radish

50-200

Rapeseed

40-160

Berseem Clover

75-220

Cowpea

100-150

Crimson Clover

70-130

Field Pea

90-150

Hairy Vetch

90-200

Red Clover

70-150

Sweetclover

90-170

White Clover

80-200

* Total Nitrogen from the entire plant

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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