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Extension > Agriculture > Crops > Forage Production > Establishment > Prevented plant: cover crop and forage options

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Prevented plant: cover crop and forage options

Phyllis Bongard

The weather continues to challenge farmers across Minnesota. With the late planting window closing, cover crop options for prevented plant acres should be considered. Crops selected for forage use would also be good choices as cover crops. There are several options depending on what a producer's needs and expectations are.

What are my options on prevented plant acres if I need forage?

Planting a cover crop for hay or grazing

If you are a livestock producer and are short on forage inventory, you may plant a cover crop for hay or grazing. However, your prevented planting payment may be significantly reduced if you harvest forage before November 1. Check with FSA and your crop insurance agent for details. Then pencil out the economics for your own enterprise to decide whether or not this is a viable option for you.

There may also be restrictions on feeding a cover crop depending on which herbicides have been used in the past. For example, crops treated with glyphosate cannot be fed or harvested for 8-weeks, while herbicides containing acetochlor (Harness, Surpass, etc.) have an 18-month restriction for grazing or harvesting certain cover crops for feed. Be sure to read all labels from herbicides used this year as well as last season for harvest and feeding restrictions and crop rotation guidelines! For more information on herbicide concerns, see Is it legal to use a cover crop as forage? Maybe not....

While alfalfa and corn silage are the preferred choices for forage quality and yield, summer annuals may help fill inventory gaps when these primary forages are in short supply and herbicide use restrictions are not a concern.

Warm-season grasses

Warm-season grasses include forage sorghum, sudangrass and sorghum-sudan. These warm-season grasses are more tolerant of drought and hot weather than cool-season small grains (oats, wheat, barley, triticale) and produce a large quantity of forage when managed carefully. Depending on your current nitrogen status, a fertilizer N application may boost forage production. While forage sorghum is generally ensiled, sorghum-sudans and sudangrasses can be grazed or harvested for hay. Grazing or green chopping young plants can result in prussic acid poisoning, so it is recommended to wait until the plants are at least 18 to 20 inches tall. When harvesting sorghum-sudan or sudangrass for hay, plants should be 3 feet tall to optimize quality and yield. In Wisconsin trials, a July 1 planting date allowed for 1 to 2 harvests and occasionally yielded as much as late-planted corn. Japanese and pearl millets, also warm-season grasses, are managed like sorghum-sudan hybrids and sudangrasses and have low prussic acid poisoning potential. If you plan to wait until November 1 to harvest, warm-season grasses will probably not be a good forage option for you. These grasses are not frost tolerant and will likely winterkill and lose significant forage value by November 1. For more information on warm-season grasses, visit the following sites:

Cool season grasses, including small grains

Cereals are cool-season crops that are usually seeded in the early spring or fall. When seeded during mid-summer, growth will be reduced by hot weather. Even so, cereals are relatively inexpensive, easy to establish and should still provide cover. Like the warm-season grasses, cool-season grasses may benefit from a nitrogen application. In addition, planting a cereal crop will help prevent "Fallow Syndrome." See Reduce risk of fallow or flooded soil syndrome with cover crops.

Annual legumes

Annual legumes, such as berseem and crimson clovers and winter peas, are a good choice for green manure or forage when planted in early spring. Late summer establishment may provide some forage, but may not yield enough to justify the seeding cost. If planted after August 1, nitrogen contributions from these annual legumes will be negligible. As annuals, they are subject to frost and will not overwinter.

Perennial legumes (excluding alfalfa)

Red clover and vetch are examples of perennial legumes. Since these crops overwinter, they would need to be controlled before the spring 2014 crop.


Brassicas include forage turnips, forage rape and radishes. They should be planted from late July into August to optimize forage yield and quality for a November harvest. Turnip tops can be grazed approximately 45 days after planting. After one or two grazings, the field can be disked so the beets can be grazed. While beet tops have a relatively high RFV (150-250), yields are generally low.


While generally not used for livestock forage, this short-season annual establishes quickly, provides good cover and scavenges soil nutrients.

Seeding alfalfa after August 1

If you are a livestock producer and have lost alfalfa to winter injury, you may wish to replace some of those acres by establishing alfalfa on prevented plant land after August 1 without penalty. In general, seeding with a companion crop is not recommended, due to potential competition for moisture. If the ground will be fallow until the late summer seeding, a chemical burn down of "natural" (i.e. weed) cover may be required. Fall harvest of a late-summer seeding is not recommended, since the risk of winter injury is high. For more information on establishing alfalfa, see the following articles:

Highly erodible land (HEL)

On slopes of more than 3 percent, crop residue cover will have to meet the conservation compliance plan requirements for those acres. Check with NRCS for complete information.

For more information


C.C. Shaeffer, personal communication, 2013.

J.J. Wiersma, personal communication, 2013.


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