Over time, what once was a monoculture of perennial grass may turn into a mixed stand of grasses, legumes, and even some unwanted species. But just because a pasture isn’t what it used to be doesn’t mean you should throw the baby out with the bathwater.
Mike Trammel, the southeast district forage specialist with Oklahoma State University Extension, says farmers can either reestablish a mixed pasture to reclaim a pure stand, or they can modify their management to optimize the available forage. In the latter case, he provided the following advice in a recent issue of the Cow-Calf Corner newsletter to make the most of the grasses — and legumes — that you’ve got.
Apply lime. Adding lime to low pH soils will encourage more clover, which will enhance diversity in a mixed stand. Trammel says liming can also boost nutrient availability to plants.
Enhance soil fertility. Fertilizer may not only boost forage productivity and persistence, but it can be strategically applied to shift species composition in pastures. For instance, Trammel says the application rate and timing of nitrogen can encourage more grass growth in stands where legumes are taking over. “Early spring and late summer applications will encourage cool-season grass growth. In contrast, late spring and summer applications will shift the mixed pasture toward crabgrass and bermudagrass,” he writes.
In general, better soil fertility will give forage a competitive edge against less desirable plants that would otherwise deprive favorable species of water and nutrients.
Match grazing to grass growth. Adjust grazing rotations and rest periods to accommodate the variety of growth patterns in mixed stands as best as you can. Trammel explains that plants acquire energy to regrow from two sources: leaves and roots. Leaves that remain after defoliation act like solar panels, capturing sunlight for photosynthesis, and the more leaf area that is left after a grazing event, the faster forage will regrow.
The way energy is stored in plant roots varies by species, which can help determine the minimum height livestock should be allowed to graze in mixed stands. Trammel says grasses that store carbohydrates in their stems are less tolerant to close and/or frequent grazing than those that store carbohydrates in crowns, stolons, or rhizomes.
“Close grazing results in a shift toward low-growing species such as bermudagrass, Kentucky bluegrass, and white clover,” Trammel states. “A higher grazing height would tend to shift the pasture mix back toward tall-growing, cool-grass species such as tall fescue and orchardgrass.”
Consider seasonality. Grazing pastures at different times of year can result in different responses from forages, too. “Grazing a mixture that includes both cool-season and warm-season species during the summer months will tend to shift the botanical composition toward the warm-season species, especially during and after drought,” Trammel cautions.
In situations where farmers choose to reestablish pure stands, Trammel recommends selecting and reseeding improved varieties to achieve higher yields, better animal performance, and greater stand persistence.
