Proper management needed to gain nitrogen from cover crops

COLUMBIA, Mo. – Some cover crops are better than others when it comes to providing nitrogen benefits in a corn-soybean cover crop rotation.

“We’re trying to understand how the cover crop may influence our nitrogen management system,” says University of Missouri Extension natural resource engineer Kent Shannon.

Shannon uses a set of sensors mounted on a baby stroller to measure light reflection or absorption by corn plants in the research plots. He ties the results to the amount of nitrogen present.

“We did see some benefit from a legume such as crimson clover giving some nitrogen credit to the corn so we didn’t have to apply as much side-dressed nitrogen,” Shannon says.

However some other cover crops failed to provide a nitrogen benefit. Shannon’s earlier research indicated corn planted after cereal rye actually needed more nitrogen. However, he says they were late killing out the cereal rye, which likely influenced the results.

Later research showed no nitrogen deficit when cereal rye was killed at the appropriate time.

Shannon says to gain a nitrogen benefit through the use of cover crops requires altering crop management techniques.

“It is going to depend on management and weather,” Shannon says. “But with the technology at least we can get a handle on how much extra nitrogen we’re going to need and be more efficient.”