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USDA Releases New Cover Crop Termination Guidelines

U.S. Map Showing Cover Crop Termination ZonesUSDA’s Natural Resources Conservation Service (NRCS) recently released its updated guidelines for terminating cover crops prior to spring planting. The guidelines apply to Iowans who farm on non-irrigated cropland.

Barb Stewart, state agronomist with NRCS in Iowa, says the most important information to take away from the new guidelines is more of a clarification on how farmers can use cover crops. “The new guidelines clearly state that haying, grazing and cutting cover for silage are all acceptable cover crop uses during a typical year,” says Stewart. “Farmers must leave enough cover crop biomass to meet the conservation purpose.”

According to Risk Management Agency crop insurance guidelines, as long as it is not a prevented planting or designated fallow year, haying, grazing or cutting cover are all acceptable. Stewart recommends checking with your crop insurance agent if you are unsure.

For Iowa farmers using cover crops to benefit their annual crops, like corn or soybeans, there are almost no other changes from guidelines released in 2013.

“Although many of the changes do not affect Iowa farmers, it serves as a good reminder of the best timing and considerations for cover crop termination,” says Stewart.

The guidelines use four strategic management zones across the country. About one-third of Iowa – the western portion – is part of Zone 3, while the remainder of the state is part of Zone 4.

For farmers in Zone 3, NRCS continues to recommend terminating cover crops at or before planting the crop. Farmers living in Zone 4 are still advised to terminate cover crops at or within five days after planting, but before crop emergence.

According to Stewart, following the updated termination guidelines provides the best opportunity for farmers to achieve conservation benefits from cover crops, while minimizing risk of reducing yield to the following crop due to soil water use.

Some cover crops winterkill, but others need to be manually terminated through tilling, mowing, or applying herbicides. If not terminated properly, cover crops can act as weeds in crop production, slowing soil drying and warming in the spring.

Stewart recommends avoiding tillage to terminate cover crops. “Tillage negates most of the soil health benefits cover crops provide,” she said, “and could lead to additional erosion issues.”

Cover crops can be an important part of a cropping system. They can be used to manage and improve soil health by adding organic matter in the soil, and living roots during more months of the year. Some cover crops – like radishes – create natural passages to improve water infiltration and grasses such as annual ryegrass scavenge nutrients that are often lost after harvest or during winter.

Cover crops also provide livestock producers with additional grazing or haying opportunities, and offer winter food and cover for birds and other wildlife. During the growing season, cover crops provide food for pollinators.

In 2013, Iowa farmers planted a record 300,000 acres of cover crops. For more information about cover crop termination, visit your local NRCS office or go online to