Covering Up

Consider Cover Crops for Prevented Planting Acres

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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Leaving prevented planting acres bare this summer can lead to serious problems with soil erosion, nutrient loss, and weed control, agronomists warn. (DTN photo by Elaine Shein)

ST. LOUIS (DTN) -- It may be a relief to see shallow lakes slowly recede from fields across the Midwest, but more work lies ahead: covering up those empty acres.

After relentless rains flooded fields and stalled planting efforts, some Midwestern growers have been forced to declare prevented planting on some acres. Now agronomists are urging them to consider planting a cover crop to limit looming problems with soil erosion, nutrient loss and weed control this summer.

In Missouri, USDA crop progress scouts reported 27% of soybean acres remained unplanted as of July 5, a date when the state's beans are usually launching into reproductive stages.

Oversaturated and ponded fields also remain in states like Iowa, Michigan, Ohio, and Indiana, where half of the state's topsoil is bogged down in surplus moisture, USDA crop progress scouts noted.

"I know if you've just lost a crop, it's hard to get enthusiastic about planting something else and paying for it," said Purdue agronomist Eileen Kladivko. "But cover crops will build up soil health, so they'll see a benefit in the crop next year compared to leaving the soil bare."

FOLLOWING THE RULES

The USDA's Risk Management Agency gives growers two options for managing lost acres for the rest of the growing season if they want to receive their full prevented planting payment. Growers can either leave the ground bare or plant cover crops that won't be harvested, hayed or grazed before Nov. 1 (which would count as an economic return on a second crop).

Growers who harvest or use their cover crops for feed before that date will receive only 35% of their full prevented planting payment. See the official RMA policy on prevented planting acres here: http://1.usa.gov/….

Before buying any cover crop seed, check with your crop insurance agent and local Farm Service Agency to make sure you aren't jeopardizing your coverage or violating any farm program restrictions, Kladivko said.

Farmers are likely to find the herbicides they applied this spring will limit their crop choices. Some herbicides can carry over and injure certain cover crops, Kladivko warned. For a good summary of which corn and soybean herbicides may pose a problem for which cover crops, see this chart from Pennsylvania State University: http://bit.ly/….

Keep in mind that if the spring herbicide you used on your prevented planting acres is not labeled for use with the cover crop you choose, haying or grazing it in the fall is a violation of federal law. See this University of Wisconsin guide to determine which corn and bean herbicides are labeled for use with some common cover crop options: http://bit.ly/….

PICKING THE RIGHT COVER

When used correctly, cover crops can be a great opportunity to boost soil health and structure, Kladivko noted.

Simply by growing, they can keep soil, wind and water erosion at bay. Their root structure can loosen compacted soils and improve soil structure. The plants themselves can use nutrients and fertilizers that you spent money on, as well as add nutrients back into the soil and build organic matter.

Perhaps most importantly, a cover crop can compete with the weeds that are sure to thrive on empty acres this summer, Kladivko added.

However, seizing on these benefits requires first knowing what your field needs, said Keith Berns, co-owner of Green Cover Seeds, which sells forage and cover crop seed.

"What are your goals for the cover crop?" Berns said. "Nitrogen fixing, erosion protection, soil building, compaction breaking, nitrogen capture, grazing?" Consider also what fertilizers you've applied and the crop you're planning to plant on those acres in the spring, he added.

For example, growers who applied nitrogen to lost corn acres should consider nitrogen-scavenging cover crops such as radish, sorghum, oats and cereal rye to recover their investment, he told DTN.

For growers who didn't get into the field with nitrogen but want to rotate to corn in the spring, nitrogen-fixing crops like peas, vetch and clovers would be a better choice.

If you plan to rotate to beans in the spring and have no fertilizer applied, focus on residue-building cover crops such as oats, rye, ryegrass, radish, sunflowers and clovers to suppress weeds and build up soil, Berns added.

Finally, keep in mind how you want to terminate the cover crop, Kladivko said. "For people just starting in cover crops, I recommend they use cover crops that winterkill and that way nature takes care of it," she said. Winterkilled cover crops are an especially good choice for acres going into corn, which requires an earlier planting date and nitrogen application, and is vulnerable to pests like armyworm, which can thrive in early spring cover crop growth.

Crops that overwinter, like cereal rye, are more easily suited to the later spring soybean plantings, but growers need to plan ahead in order to terminate them before they gain too much biomass, she added.

For more information on how to best select a cover crop for your acres, see this Purdue University press release: http://bit.ly/…. For more details on terminating cover crops, following insurance guidelines, and timing the planting of your cover crops, see this National Resources Conservation Service page: http://1.usa.gov/….

The Midwest Cover Crops Council also serves as a comprehensive guide to all aspects of growing cover crops, from seeding to termination: http://www.mccc.msu.edu.

Emily Unglesbee can be reached at emily.unglesbee@dtn.com

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(PS/AG/CZ)

Emily Unglesbee