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Serving: IA
CHOICES: There are many choices for cover crops; weigh the pros and cons, and how each fits your situation.

Cover crop options for prevented planting fields

As you consider alternative crops, know seed for some forages is in short supply.

Whether it's too much rain or perfectly timed rain, many fields are flooded or too wet to continue planting in many parts of Iowa. Delayed and prevented planting crop insurance dates are fast approaching with an unfavorable weather forecast. Decisions surrounding your situation with delayed planting and the prevented planting provision need to involve a conversation with your crop insurance provider.

An article available on the Iowa State University Ag Decision Maker website discusses the insurance provision implications. Also, there are articles addressing Late Corn Planting Options and Late Soybean Planting Options. These articles discuss late-planted yield potential. “Each choice has practical and economic implications. You need to approach these decisions with caution and armed with good information,” says Mark Licht, ISU Extension cropping systems agronomist.

Take option?

Licht, with the help and input of several ISU Extension field agronomists who work in various locations around the state, offers the following guidelines for farmers to consider.

If prevented planting is taken, it is highly recommended to plant a cover crop or an emergency forage crop rather than letting the field be fallow through the summer. 

However, note that under prevented planting provisions, a cover crop or emergency forage cannot be grazed or harvested for forage until after Nov. 1 and cannot ever be harvested for grain without reduction to the prevented planting coverage payment. You need to discuss this with your crop insurance provider.

Cover crop considerations

If producers are prevented from planting corn or soybeans, they should consider either planting a forage crop as a second crop or a cover crop to help with weed management, to help keep the soil healthy and alive and to potentially realize a return from another crop:

Winter cereals (rye, wheat, triticale) can be planted as early as August with good success of winter survival and high forage yield potential in spring. Use a minimum seeding rate of 45 pounds per acre for a cover, but twice that amount if you want to maximize a forage harvest of the cover crop in the spring. You’ll have the best success when planting is followed by rainfall. Seeding with a drill is more uniform than broadcast or aerial seeding. Winter cereal rye is generally the most economical choice.

Spring cereals (oats, wheat, barley) can be planted any time before Sept. 15. When planted early, they will likely produce a seed head that will shatter causing some reseeding.

Soybeans can be planted as a prevent planted cover crop option. It is recommended to plant in rows narrower than 15 inches, or you can broadcast the seed. A row crop planter can be used by planting at a one-half seeding rate in the normal row direction followed by planting perpendicular, at an angle, or offset from the original row. Use a seeding rate of 60,000 to 80,000 seeds per acre, maybe slightly higher if broadcast seeding.

Narrower rows and a lower seeding rate will support branching to achieve canopy closure more quickly to provide competition against weeds. Another consideration is that soybeans might be a viable option as a cover crop because you can use treated seed that has already been purchased.

Corn can be planted as a prevented planting cover crop option. This is not a preferred option because of challenges associated with fall crop residue management, future volunteer corn, and seed cost. If using corn as a cover crop on prevented planting acres, use a seeding rate of 60,000 to 80,000 and narrow row spacing as mentioned above in the soybean considerations. This will promote faster canopy closure and reduce the number and amount of viable seeds produced.

Brassicas (turnips, kale, forage rape, radishes) should be planted from late July into August for best biomass. If planted in June, most of these will likely bolt and produce seed by fall. They can be planted with a cereal grain, such as oats, triticale or rye. The brassicas will winter-kill, but they are highly frost-tolerant and will remain a good grazing forage well into November.

Legumes (crimson clover, berseem clover, field pea, hairy vetch, common vetch) are slower to establish and more expensive than other cover crop options. Seeding should occur in August to ensure adequate growth that would lead to higher overwintering success.

Editor’s note: This article contains information from two previous ICM News articles written by retired ISU Extension forage agronomist Steve Barnhart: Prevented Planting and Cover Crop Considerations, June 2013, and Forage and Cover Crop Considerations for Delayed Planting and Flooded Sites, June 2008.




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