Gaps in summer forages for livestock producers can be challenging. University of Missouri Extension agronomy field specialist Valerie Tate in Linn County shares management solutions, including planting warm-season annual forages such as pearl millet and sorghum-sudangrass, to fill a void in summer forage production or when renovating forage stands.

“When moisture and soil nutrients are readily available, sorghum-sudangrass and pearl millet can produce up to 6 tons of forage per acre during the growing season,” Tate said.

Crops such as foxtail millet, Japanese millet or improved crabgrass can also be used, but are not as productive, she said.

When to plant

Plant sorghum-sudangrass in mid-May to late June when soil temperatures reach 60°. Drill sorghum-sudangrass at a rate of 20-25 pounds (lb.) per acre, or broadcast it at a rate of 30-35 lb. per acre. For successful establishment, plant at a depth of ½ to 1 inch (in.) into a firm, tilled seedbed; or control weeds with a burn-down herbicide when using no-till. Drill pearl millet at a depth of ¾ to 1 in. deep at a rate of 15 lb. per acre, or broadcast it at a rate of 20-30 lb. per acre in mid-May through mid-June. Sorghum-sudangrass prefers a soil pH above 5.5. Pearl millet is more tolerant of acidic soils than sorghum-sudangrass.

How to maintain

The key to maintaining high-quality summer annual forage throughout the growing season is to keep the plants from becoming too mature. The first harvest can occur 45-60 days after planting. Harvest or graze sorghum-sudangrass and pearl millet when the plants reach 24-36 in. in height, leaving a 10-in. stubble to promote regrowth. If the plants are allowed to grow beyond 36 in. in height, forage quality drops dramatically. To maximize production, apply 60 lb. of nitrogen fertilizer at establishment, and 40-60 lb. after each harvest.

Careful with grazing

Use caution when harvesting or grazing summer annual forages during periods of prolonged drought. Nitrates can accumulate in the lower stems, resulting in nitrate poisoning. To minimize the risk of nitrate poisoning when conditions are dry and forage growth is slow, delay additional applications of nitrogen fertilizer until adequate moisture is available for rapid plant growth.

Prussic acid poisoning is also a concern with sorghum-sudangrass following frost injury or drought stress. Do not graze sorghum species before they reach 24 in. in height, and do not graze plants for 14 days after they have been stressed or damaged by drought, frost or hail.

Making bales

It can be difficult to get the coarse stems of sorghums and millets to the 18% dry matter necessary to prevent spoilage of dry hay. Making baleage by wrapping bales with plastic at a high moisture content is an alternative. Forage is mowed and allowed to wilt to 45%-60% moisture. This may take six-24 hours, depending upon the crop, yield, swath density and weather. After it is baled, it should be wrapped in plastic within four hours, if possible. The bales will undergo the ensiling process, which might take up to six weeks.

The keys to making high-quality baleage are:

• Make tight, dense bales to eliminate as much oxygen as possible.
• Make wet bales smaller than dry hay bales for ease of handling.
• Use plastic twine or net wrap rather than treated sisal twine, which can break down the plastic.
• Wrap with six layers of 1-mil. white plastic.
• Store bales in a well-drained area near where they will be fed.
• Repair tears in the plastic with silage tape to avoid spoilage.

For more information refer to these related MU Extension guides:

• Warm-Season Annual Forage Crops
• Growing Millets for Grain, Forage and Cover Crop Use

Editor’s note: This article is from University of Missouri Extension.  [Lead photo by Valerie Tate, University of Missouri.]