Adding Forage Options with Summer Annuals

Consider warm-season annuals as part of your forage rotation.
By: Warren Rusche, Cow/Calf Field Specialist, SDSU Extension

Warm-season annuals are excellent options to consider as a way to increase a farm or ranch’s forage production. These are a group of annual grasses that perform best during the warmest part of the summer and are typically planted in June or July. These crops can be a complement to cash grain and cover crops to enhance forage production or grazing opportunities.

The most common warm-season annual planted in the Northern Plains are the hay millets, pearl millet, sudangrass and sorghum-sudan hybrids, and forage sorghums. Each of these crops has advantages and disadvantages, depending on the environmental conditions and the planned usage.

Hay Millets

• As the name implies, these crops are best suited to be harvested as hay rather than grazed or cut for silage. These plants have finest stems and cure the easiest compared to other summer annuals. Hay millet is most drought-tolerant and can produce forage in as little as 8 weeks after planting.

Pearl Millet

• Pearl millet offers more production potential than do the hay millets. Pearl millet has the ability to re-grow, making it a better option for grazing or for multiple cuttings at any growth stage. Pearl millet has coarser stems than hay millet, making curing for baled hay more challenging. Unlike sudangrass, sorghum-sudangrass and forage sorghum, pearl millet doesn’t accumulate prussic acid, which means that cattle wouldn’t have to be temporarily removed because of an early frost.

Sudangrass and Sorghum-Sudangrass Hybrids

• Because of the thicker stems for these crops, they are much better suited to be harvested as silage compared to hay. These also work well as supplemental summer grazing. Prussic acid can be a concern when grazed. The greatest risk for prussic acid poisoning occurs under drought conditions, when plants are damaged by frost, or when livestock graze short regrowth. To minimize risk defer grazing until sudangrass is 18 to 20 inches tall and sorghum-sudangrass hybrids reach 24 to 30 inches. Remove livestock for 5 to 6 days if these plants are damaged by a killing frost so that the plants can dry out and the prussic acid can dissipate.

Forage Sorghum

• This crop is the latest maturing and has the most production potential. Forage sorghum is best suited for silage production.

Other Factors to Keep in Mind:

• As with all forages, maturity at harvest determines quality. Earlier harvest dates will result in higher quality forage. Delaying harvest will tend to increase dry matter yield.
• Prior crop history needs to be considered as well. Prior herbicide usage, especially for products such as atrazine can impact stand establishment. Soil sampling and testing is also important to determine proper fertilizer application rates.
• Before a grower considers planting an annual forage crop, they should visit with their crop insurance advisors to make sure they are not jeopardizing coverage.