Spring will arrive before we know it. There will be new growth emerging from seedlings and plants that have been dormant through the winter. With sufficient moisture, life will spring forth across the range, thus beginning a new growing season. However, last year was dry and many native grass pastures have been heavily used this winter - in many cases leaving little residual forage. Now is the perfect time to begin planning how to manage native grass pastures for this season.
Much of the planning depends on the goals for the pasture and exactly what there is to work with. If you have significant stands of the preferred tallgrasses, such as Big bluestem, Little bluestem, Indiangrass, Switchgrass and perhaps Eastern gamagrass, you are probably at an advantage over those who do not. But even if you have a presence of these grasses, it will benefit you to plan to manage grazing around these key species. The easiest means to discuss this without writing a dissertation is to give an example.
The Noble Research Institute Ag Division operates several properties in southern Oklahoma. At the Coffey Ranch, on a 20-acre pasture (one of the least productive), a mixture of desirable native grasses including Eastern gamagrass was broadcast and then trampled into the soil with cattle. Several springs later, the resident manager of the Coffey Ranch, Kent Shankles, noticed what appeared to be seedlings of the more desirable tall grasses. He conferred with several Ag Division forage specialists, and we decided to change the grazing management of the pasture for the season. Previously, the pasture was dominated with mid-seral grasses, predominantly broomsedge bluestem, and had been grazed intensely and often (rotationally) during the early growing season, leaving a 2- to 3-inch residual plant height and returning for another grazing event in about 25 to 30 days. The objective of this type of grazing was to use a less-desirable forage as much as possible, delaying the onset of growth of reproductive structures. The new grazing strategy was to graze the pasture only long enough to maintain a minimum of a 6-inch residual on the desirable grasses, which turned out to be mostly Eastern gamagrass with some Switchgrass, and extend the recovery period to 45 to 60 days during the early growing season and even longer later in the season when moisture conditions were poor. We guessed we would be sacrificing some grazeable production in the short-term for long-term benefit of the stand.
The results were surprising. At the end of the growing season when managing the grazing for the Eastern gamagrass plants, the grazed production from the pasture had actually increased over previous years totals, from about 30 AUDs (animal unit days - AUD = 26 lbs. DM per acre) to 58 AUDs. The following years showed an increase in AUDs upwards of 90 AUDs when the same grazing management was practiced. After each growing season, plant residuals exceeded 10 inches going into the winter, and, furthermore, this occurred during the late 1990s, which were not known as abundant rainfall years.
All that said, the only reason why this was observed and documented was because Kent was looking at his pastures in the spring prior to turning in the cattle. The question then became, "How many tallgrass plants does it take to impact the grazed production?" Upon establishing ten random transects, the basal intercept (ground level) of plants along these transects averaged just over 5 percent the third and fourth years post emergence. Granted, not all tallgrasses have the same growth structure as Eastern gamagrass, but the take-home message is it does not take very many tallgrass plants to significantly impact production. If you have tallgrasses present in native grass pastures, address grazing management to improve or sustain range condition. That does not mean everyone should rotationally graze cattle through pastures as indicated in this example, but recovery periods and residual plant heights need to be a significant part of the management scheme.