Capturing Unused Nitrogen is Serious Business

Still time to plant cover crop to tie up most of the N.

Published on: Oct 3, 2012

Time is growing short if you're going to take action to try to capture N that your corn crop didn't use by seeding a cover crop this fall. Dave Nanda, a consultant and director of genetics and technology for Seed Consultants, Inc., thinks it is one of the more important things you can do following this droughty year.

Otherwise, he says, nitrogen will leach below the reach of next year's corn or soybean crop. It may also leach out into waterways through tile lines and cause environmental watchdogs to throw the red flag, warning that nitrates are high and again contributing to such serious conditions as hypoxia (a lack of oxygen for fish) in the Gulf of Mexico.

Come back with corn? Dave Nanda makes a case for following corn and a cover crop planted to capture N with corn rather than soybeans.
Come back with corn? Dave Nanda makes a case for following corn and a cover crop planted to capture N with corn rather than soybeans.

By now your best choice is likely wheat or rye. You may still be able to seed annual ryegrass, depending upon where you live, but the window to successfully seed it and get a good stand with enough growth going into winter is closing fast. On the other hand, wheat and rye typically will survive and produce spring growth if planted into early November, although earlier planting is recommended. How well they grow next spring following late planting depends partially upon winter conditions.

Nanda points out that if you elect to use a cover crop to capture N, you may want to think about going back to corn in that field rather than soybeans. While it could break up your normal rotation, the nitrogen that is captured and released as the cover crop breaks down would be more beneficial for corn than soybeans.

The kicker is that if you're planting corn, especially corn after corn, you need to order seed quickly to have a good shot at getting the best hybrids. For corn after corn, you need hybrids with a good disease package. Nanda anticipated that the best hybrids will be in short supply, and should be ordered and locked in as soon as possible.