Cover crops are often considered for the functions derived from the first half of their name. Erosion control, reduced runoff, and less nutrient leaching are just a few of the benefits of covering the soil. But when cover crops are managed as intensively as other forages, they can add value to livestock systems as well.
At the American Forage and Grassland Council’s Annual Conference earlier this month in Mobile, Ala., Marcelo Wallau with the University of Florida discussed how to graze livestock on cover crops more effectively. The extension forage specialist said there is potential for better crop and animal performance in an integrated system when producers invest in fertilization and grazing management.
“If we don’t treat cover crops as actual crops, they aren’t going to produce as much,” Wallau said. “Because I’m investing in those plants, I can have better pastures, and because of better pastures, I can have better cattle.”
Fertilizer is a must
Wallau noted some producers might not be in favor of fertilizing cover crops and raising their cost of production. However, he argued that a better average daily gain in cattle from higher crop yields and a longer grazing window could justify fertilizer prices and make the system more profitable overall.
“We often talk about reducing fertilization, but if fertility is added, we are going to be able to graze more, and much earlier,” Wallau stated.
Research has shown that proper grazing management can further enhance cover crop yields, as well as the environmental benefits they provide. For example, Wallau referred to a study conducted in southern Brazil — where the climate is similar to that of the southeastern U.S. — that compared the effects of moderate and heavy grazing on cover crop production and animal performance.
In the latter treatment, cover crops were overgrazed, exposing the soil and exacerbating the rate of nutrient loss. Less ground cover also encouraged more weed growth compared to the moderately grazed areas. What’s more is the heavily grazed cover crops had smaller, weaker root systems.
Wallau noted a third treatment group of cover crops that were not grazed also had less vigorous root systems. He explained moderate rotational grazing stimulates more growth aboveground over the course of a grazing season, which strengthens root systems belowground as well.
Each system is unique
Wallau defined moderate grazing as allowing animals to utilize 50% of cover crops in a field before moving livestock to another area. He advised against trying to maximize cover crop harvest, noting the difference between harvest efficiency and utilization efficiency.
“Whenever we are harvesting less of a plant, we can have greater forage production because there is better residual leaf area and those plants will grow back faster,” he stated. “This translates to a greater average daily gain because the animals are grazing a better part of the canopy.”
When implementing moderate grazing, Wallau said stocking rate, grazing frequency, and the timing of grazing will vary from farm to farm. Instead of offering specific management instructions, he encouraged members of the audience to assess their own stocking rate and then adjust their grazing start date and the length of grazing rotations from there.
In concluding, Wallau acknowledged that not all livestock producers have adequate land to graze cover crops, and not all crop producers have livestock. He pointed to custom grazing as one solution for farmers to work together and make the most of both systems.