Texas A&M AgriLife Extension Service specialists and Texas A&M AgriLife Research scientists developed four new fact sheets that walk farmers through the basics of growing cover crops for grazing, from selecting species and assessing biomass to evaluating grazing economics and animal safety risks.

“Because of the many questions about grazing cover crops and limitations in semi-arid regions, we created the series of fact sheets to address details that producers should consider,” said Jourdan Bell, Ph.D., AgriLife Extension agronomist and associate professor in the Department of Soil and Crop Sciences, Amarillo. 

The fact sheets represent the work of 14 AgriLife Extension and AgriLife Research experts in the Department of Soil and Crop Sciences, Department of Animal Science, Department of Rangeland, Wildlife and Fisheries Management, and Department of Agricultural Economics.

Cover crops basics

Different cover crop species offer different soil health benefits, and not all are adapted to the Southern Great Plains.

In this region, summer cover crops may include blends of sorghum-Sudan grass, millet, cowpeas, okra, sunflowers and other drought-tolerant, warm-season annuals. Monocultures of sorghum-Sudan, millet or cowpeas can also work and may provide producers with beneficial summer and fall forage, depending on the season.

While winter cover crops are most commonly used in rotation with low-residue summer crops such as cotton, summer cover crops can also offer both grazing opportunities and soil health benefits.

Cattle move between a field planted to a cover crop and a grass pasture. Producers in the Southern Great Plains must balance forage type and quantity with grazing duration to make grazing cover crops economically viable. (Paul DeLaune/Texas A&M AgriLife)

Key questions before grazing cover crops

Grazing cover crops can boost soil health and provide a valuable forage source, but only if there is enough biomass to support livestock production and still protect the soil.

Producers should ask these questions before turning out livestock:

• Forage type: Are there any toxicity concerns?
• Forage quantity: Is there enough forage to make grazing economical?
• Grazing duration: How can you graze while still protecting soil health?

For instance, hairy vetch is often used in cover crop mixes as a legume with strong root activity; however, it should be avoided if grazing livestock, as hairy vetch toxicosis can be fatal for certain classes of livestock.

Additionally, nitrates can accumulate in water-stressed cover crops, such as small grains. Producers should factor in current and previous fertility programs when deciding whether stressed forages are safe to graze.

“It is important to always consider your cover crop objective before initiating grazing, including how much biomass you need, how much you plan to leave and when to terminate the cover crop,” said Emi Kimura, Ph.D., AgriLife Extension agronomist and associate professor, Vernon.

Making the economics and logistics work

Biomass quantity is a primary factor for determining if a field is suitable for grazing. In Southern Great Plains grazing systems, there should be at least 90 days of forage available to justify the cost of grazing.

For example, if stocker cattle gain 1.5-2 pounds per day, the cost of the gain should be less than the cost of grazing to ensure a net profit.

While grazing cover crops can add value by improving soil health, producers also should consider:

• Transportation costs.
• Water access and fencing.
• Other basic livestock needs.

 “The stocking rate should be based on potential forage intake and total animal weight rather than the number of animals,” Kimura said. “As long as the field is not overstocked, forage production will continue to increase under nonstressed conditions and also benefit soil health.

To help producers evaluate if grazing cover crops is right for their operation, all four fact sheets are available online at the Southern Great Plains RegenAg site. The documents are part of a larger U.S. Department of Agriculture National Institute of Food and Agriculture project including researchers and Extension specialists from Oklahoma State University and Texas Tech University.