Forage Options with Prevented Planting Fields

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 delayed and prevented planting provision need to involve a conversation with your crop insurance provider. There is a nice article available on the Ag Decision Maker website that talks about the insurance provision implications. There is alsoa recent ICM News article called "2024 Cover Crop Options in Prevented Planting Fields."

Additionally, 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; approach this decision with caution and armed with good information.

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

Please note: under prevented planted provisions a cover crop or emergency forage can be grazed or harvested for forage at anytime but cannot be harvested for grain without reduction to the prevent plant coverage payment. Please discuss this with your crop insurance provider.

Annual Forage Crop Alternatives

There are a couple of considerations when selecting forage options: some will offer grazing or harvested forage very quickly, while others will take longer before they can be used, and planting timeframe will vary. Therefore, the strategy of what and when to plant depends on the final objective. When considering crops for annual forage, practical options include grazing, dry hay, green chop, and silage (Table 1). While many crops may work as forage, those listed in Table 1 are the most practical, predictable, and economical. Seed supplies for some of these forage crops may be limited due to increased demand, so it's important to check seed availability as you consider your options.

When considering forage species for prevented planting acres, review carefully what herbicides were used earlier in the spring for corn or soybean planting. This can restrict what you may be able to plant, and if there are restrictions on when it can be harvested or grazed for forage. Additionally, some herbicides from the prior growing season might have restrictions that need to be considered. Here is a resource that can be used to access herbicide labels.  Additionally, if a high rate of pre-plant nitrogen was applied for corn, it would be appropriate to screen the warm-season annuals (except teff) for potential nitrate accumulation.

Table 1. Forage uses, seeding rates, plant by date, estimated yields, and potential toxicities.

+ Silage, haylage, or baleage
^±PA = Prussic Acid, N = Nitrates

Sudangrass is a multiple-cut, summer annual; used for green chop, pasture (rotation grazing is recommended), or silage; difficult to dry thoroughly for hay; varieties vary in height and leafiness. Plant through early-July. The first growth is usable in about 30 to 40 days. Leave a 6-inch stubble height to maximize regrowth. Prussic acid poisoning risk is minimal but avoid pasturing severely drought stressed or very short (<18 inches) growth/tiller regrowth and do not graze following a frost for at least one week, or until that plant is killed.

Sorghum × Sudangrass can be used as a multiple-cut or single- cut, summer annual; used for green chop, pasture (rotational grazing is recommended) or silage; varieties vary greatly in height, leafiness depending on the parent lines making up the hybrid. Plant through early-July. The first growth is useable in as little as 30 days in the optimum environment, and regrowth is from tillers. Leave a 6 to 8-inch stubble height to maximize regrowth. There is prussic acid poisoning risk if plants or tillers are grazed or green fed at short height (<24 inches) or during severe drought and do not graze following a frost for at least  one week, or until that plant is killed.

Forage Sorghum is a single-cut, summer annual; used for green chop, and silage. Varieties can vary greatly. It can be planted until mid-July. While useable in 40 to 50 days, it will take approximately 15 to 25 days longer to reach soft dough (ideal timeframe for silage harvest).  Will terminate with a fall frost.  There is prussic acid poisoning risk if plants or tillers are utilized for green chop at short height (<24 inches) or during severe drought or following a frost. If prussic acid is a concern, ensiling estimates a 50% reduction in prussic acid potential.

Sudangrass, and sorghum × sudangrass, and forage sorghum hybrids are better adapted than most species to drought, high temperature and low soil pH but will yield less in seasons with cool August and September temperatures

Pearl Millet is a multiple-cut, summer annual; green chop, pasture (rotational grazing is recommended), or silage; resembles sorghum × sudangrass hybrids in plant structure. Usable in about 30 to 45 days. Leave a 6-inch stubble height to maximize regrowth. Somewhat slower regrowth than sorghum × sudangrass hybrids; poor production in cool summer seasons; no risk of Prussic acid poisoning. Will terminate with fall frost.

Foxtail Millet, also called German, Siberian or hay millet, is a summer annual grass used as harvested or grazed forage. Plant through mid-July. Useable in about 50 days. Foxtail millet is  great option as an emergency hay crop; can become a weedy grass if allowed to produce mature seed. Will terminate with fall frost.

Japanese Millet is a summer annual grass; relatively coarse (stemmy) forage; used as green chop, hay, silage or pasture. Plant through mid-July. Useable in about 50 days. Very little regrowth if first growth is allowed to reach maturity. Leave a 5 to 6-inch stubble height to maximize regrowth. Closely related to the grassy weed barnyard grass, so avoid allowing seed formation.

Teff is summer annual grass. It is a fine stemmed, leafy forage of good quality, that needs a firm seed bed. If well-established, it can be used in about 40 to 45 days.  Dry-down for hay is difficult. A shallow root system makes it problematic for grazing. Good, rapid regrowth following harvest depends on leaving a stubble height of at least 4 to 5 inches.

The summer annuals are a great option to produce forage quickly during the height of the summer, and each will terminate will fall frost. Here are some more opportunities outside of the summer annual grasses.

Spring Cereals (Oats, Wheat, Barley) can be planted in June or July as a cover crop, can be grazed about any time. Will likely head at a short height and shattering will occur. Can be cut and stored as dry hay or silage form late-vegetative through early milk stage. At dough stage, the stems decrease feeding value greatly. Oats are usually the cheapest option.

Berseem Clover is an annual legume that grows well in a wet summer. It requires a specific rhizobium for nodulation. Like alfalfa, first growth is useable in about 60 to 70 days. The seed is more expensive than other species. Can be planted till mid-August. It is terminated with a killing frost.

Italian Ryegrass can be planted through August and would provide some forage for grazing in November. There would likely be a hard freeze before then, but still provide available grazing forage.

Winter Cereals (Rye, Wheat, Triticale) can be planted as early as June or July. They will remain vegetative through the season only reaching a height of about one foot. There is no stem production until it goes through the winter. Clipping winter rye in late summer is advised to ensure overwintering success. Winter triticale would be expected to respond similarly whereas winter wheat would likely experience winterkill. Suitable for grazing and forage.

Winter cereals planted in 2024 and harvested in the spring of 2025 can be ensiled and make good feed for young stock and even mature animals. When harvesting silage, moisture content is critical. The target is similar to corn silage at 35% dry matter or 65% moisture. These forages tend to dry-down fast, so it is better to plan harvest when final dry matter is around 35%. Because of the structure of the stem, high packing density is essential for good fermentation. To achieve high density, harvest at boot stage and chop at ½ inch or shorter length. The use of silage inoculants is highly recommended for this type of forages.

This article has been adapted from two previous ICM News articles; Prevented Planting and Cover Crop Considerations, June 2013, and Forage Options with Prevented Planting Fields, May 2019.