USDA Releases New Cover Crop Termination Guidelines

USDA Releases New Cover Crop Termination Guidelines

USDA/NRCS has released updated guidelines for terminating cover crops prior to spring planting in 2014.

By Jason Johnson

USDA's Natural Resources Conservation Service in Iowa has released its updated guidelines for terminating cover crops prior to spring planting in 2014. 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 gather 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 covers for silage are all acceptable cover crop uses during a typical year," says Stewart. "But farmers must leave enough cover crop biomass to meet the conservation purpose."

TO KILL A COVER CROP: Some types of cover crops die out during winter, other types need to be killed by applying herbicide prior to planting. NRCS has issued new guidelines for when to kill a cover crop this spring. Timing is important.

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


Thinking About A Cover Crop? Start With Developing A Plan
Taking time to design your cover crop plan will increase the successful establishment of the crop and potentially allow for improved staggering of fall harvest.


For Iowa farmers planting cover crops to benefit their annual crops of corn or soybeans, there are almost no other changes from guidelines released in 2013. "Although many of the changes don't affect Iowa farmers, it serves as a good reminder of the best timing and considerations for cover crop termination," she says.

NRCS map shows Iowa zones which recommend when to kill cover crops
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.

USDA Releases New Cover Crop Termination Guidelines

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Stewart says 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, others need to be manually terminated through tilling, mowing or applying herbicide. If not terminated properly, cover crops can act as weeds in crop production, slowing soil drying and warming in spring. Stewart recommends avoiding tillage to terminate cover crops. "Tillage negates most of the soil health benefits cover crops provide, and could lead to additional erosion issues," she notes.

A map showing the Iowa zones, along with more recommendations for managing cover crops, are on the NRCS Iowa website
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 soil, and living roots during more months of the year. Some cover crops, like radishes, create natural passages to improve water infiltration. Grasses such as annual ryegrass scavenge nutrients that are often lost after harvest or during winter. Cover crops also provide livestock farmers with additional grazing or haying opportunities, and offer winter food and cover for birds and wildlife. During the growing season, cover crops provide food for pollinators.


Thinking About A Cover Crop? Start With Developing A Plan
Taking time to design your cover crop plan will increase the successful establishment of the crop and potentially allow for improved staggering of fall harvest.


For information about cover crop termination, visit your local NRCS office or go online to the Iowa NRCS website and click on "Agronomy." That section of the site has a map showing Iowa's management zones for cover crop termination. In the fall of 2013 Iowa farmers planted a record 300,000 acres of cover crops.

Johnson is a public affairs specialist for USDA/NRCS in Des Moines.

TAGS: Soybean
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