Todd and Arliss Nielsen inspect their ryegrass cover crop in Wright County, Iowa. USDA photo.
A growing number of farmers throughout the nation have “discovered the cover” — and for some very good reasons.
They’re recognizing that by using cover crops and diverse rotations, it’s possible to actually improve the health and function of their soil, said David Lamm, a soil health expert with USDA’s Natural Resources Conservation Service.
Farmers are also reaping the benefits healthy soils bring to their operations in the form of better nutrient cycling, improved water infiltration and more consistent yields over time.
“The principles of building healthy soils are the same everywhere — you have to stop tilling the soil and switch from a monoculture crop rotation to one with a diversity of crops that should include cover crops,” Lamm said. “But the path to soil health is different on each farm.”
Keeping soil covered and growing with living roots is a critical component in improving the health and function of the soil, Lamm said.
“That means understanding how to manage cover crops in a soil health management system, and that can be one of the biggest challenges farmers face,” he said.
Cover crop and cash crop selections and rotation sequences should be chosen to fit the farmer’s resource concerns and priorities, and the resources available at that farm.
“Farmers not familiar with how mixtures of cover crops work together might ask ‘why would I want to plant a cover crop that uses up all my water?’” Lamm said. “But using diverse annual cropping rotations and cover crop combinations increase soil organic matter. And for each 1 percent in organic matter, there can be a 25 percent increase in water holding capacity and up to 30 pounds an acre more of available nitrogen.”
While it is true cover crops use some soil profile water, they simultaneously improve the soil structure by building soil aggregates, he said. They also provide mulch that reduces evaporation and runoff losses and break up subsoil to increase water recharge.
“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. “Those covers actually help protect farms against weather extremes like drought.”
Learn more about cover crops and “Unlock the Secrets in the Soil,” the agency’s soil health awareness campaign.
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