Sudangrass is a viable forage alternative for Chouteau County

Sudangrass is a good haying and grazing alternative for Chouteau County livestock producers. Sudangrass can be seeded and harvested with conventional equipment in normal crop rotations. Secondly, working with a warm season crop helps distribute the farming workload because seeding takes place in late May or early June. Lastly, later seeding results in effective weed and disease management.

Sudangrass must be seeded after soil temperatures are consistently above 60 degrees Fahrenheit. After establishment, sudangrass can be very productive on dryland. Compared to small grain forages, warm season forages typically yield more forage per inch of soil moisture. Depending on moisture, warm season forages can yield 1.5 to 6 tons of dry hay per acre.

Sudangrass serves as an excellent pasture or hay crop. Having three feet to five feet height and slender, leafy stems make sudangrass well suited for pasture, dry hay, or silage. Sudangrass requires 60 to 90 days of frost-free weather with soil temperatures of 65 to 70 degrees Fahrenheit. Sudangrass can be drilled or broadcast at a seeding rate of 25 to 30 pounds per acre. Under irrigation, the seeding rates should be increased to optimize forage yield and quality. Seeds should be planted 1 to 1.5 inches deep into a firm seedbed. A good fertilizer guideline is to supply about 20 pounds of N per every ton of anticipated yield. Phosphorus and potassium requirements are similar to those of small grains.

Sudangrass is best suited for grazing or hay production. Sheep can be turned out when the crop is 12 to 14 inches tall, and cattle when the crop is 18 to 24 inches tall. Livestock should not graze the crop below about 4 inches to allow for fast regrowth. For optimum use, fencing should be used to set up a rotational grazing scheme. Sudangrass should be cut for hay in the heading stage, or for silage in the dough stage.

Disadvantages of sudangrass include deep water removal in the summer, nitrate toxicity and prussic acid toxicity. Many grasses have high

nitrate accumulations in the early stages of growth, and particularly during drought stress. MSU Extension provides a nitrate “QuikTest” on a representative sample of the crop prior to cutting or grazing. In addition, Prussic acid (hydrocyanic acid) produces toxic effects in livestock. Commercial laboratories can analyze for prussic acid concentrations, but sampling and timeliness are critical. Prussic acid hay is not a high concern for testing because the acid levels start decreasing as soon as the sudangrass is cut. Conversely, sudangrass needs to be tested before it is grazed. Prussic acid levels decline after a killing frost.

Information for this article comes from Dennis Cash (former MSU Extension Forage Specialist, Emily Meccage (former MSU Extension Forage Specialist) and Mike Schuldt (MSU Extension Custer County). Copies are available at the Chouteau County Extension office located in the green building behind the Chouteau County Courthouse.

Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.