The use of multiple pastures for grazing systems provides opportunities for valuable year-to-year changes in when pastures are grazed.
Choosing a Grazing System
Rangeland may be divided into pastures to provide control over the time and extent to which plants are grazed. Cross fencing is often used to separate range sites with different kinds and quantities of plant species.
In addition to keeping livestock from concentrating on preferred range sites, multiple pastures can be used to enhance vigor of preferred plant species. The sequence or season in which pastures are grazed can be changed enough each year to avoid having two years in a row of heavy grazing of preferred plant species during rapid growth. Rotation grazing systems with four or more pastures allow ranchers to make meaningful year-to-year changes in when pastures are grazed.
Because grazing systems simply define periods of grazing and non-grazing, there can be an overwhelming number of potential grazing systems; however, environmental, economic, and resource constraints limit the number of acceptable systems. Most feasible grazing systems fit into the following four categories: season-long continuous grazing, rest-rotation grazing; deferred rotation grazing; and intensively managed grazing.
When different grazing systems have a similar likelihood of accomplishing your objectives, the simplest system generally is the most economically and ecologically efficient.
Pasture Grazing Order
Almost all of the production of different grass species on semi-arid rangeland occurs during 30-day rapid-growth windows, when air temperatures and soil water are most favorable for each species. (See Season and Timing of Plant Growth)
Preferred mid- and tall-grasses are most likely to be overgrazed when livestock are present during the grasses' respective rapid-growth windows. (See Grazing and Drought) Overgrazed grasses or sedges are unlikely to fully recover from heavy grazing in the current year when soil water deficits limit growth.
Simple tools such as the Grazing Response Index and Sandhills Defoliation Response Index are very helpful in determining pasture grazing order.
When using rotation grazing systems, ranchers commonly change the order in which rangeland pastures are grazed each year. Knowing how and when your plants grow will help you graze in a way that improves plant vigor, range condition, and next-year's forage production potential.