Monday, September 23, 2013

When it comes to water, cover crops give more than they take, expert says

It’s a fair question. Why would farmers want to plant a cover crop that uses up water? But David Lamm, a soil health expert with USDA’s Natural Resources Conservation Service, says it’s what those cover crops give – not what they take – that’s the secret.

 “By using diverse annual cropping rotations and cover crop combinations increase soil organic matter. And for each 1 percent in organic matter, there is a 25 percent increase in water holding capacity and up to 30 pounds an acre more of available nitrogen,” he said.

In a recent survey by the Conservation Technology Information Center, 600 farmers affected by the drought
of 2012 reported an average increase of 14 bushels of corn per acre and five bushels more of soybeans per acre where they had a cover crop as compared to none.
Lamm said that while it’s true cover crops use some water in the soil profile to grow, they simultaneously
improve the soil structure by building soil aggregates, providing armor for the soil surface, and recharging the
water in the soil profile though increased infiltration.

“By using cover crops, no-till and crop rotations, farmers are finding that their soil actually has more available water for their cash crops when those crops really need it,” he said. “So those covers actually help protect farms against weather extremes like drought.”

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