Written by Rachel Frost and Jeff Mosley, Montana State University
When properly implemented, a grazing system can help rangeland and livestock managers achieve management objectives related to rangeland and livestock production and ecosystem structure and function. Selection of the proper grazing system depends upon understanding the unique combination of topography, soils, vegetation types, and climate that overlap the management unit. No grazing system is better than any other, but each system is appropriate for specific conditions.
A grazing system is a particular way of managing the interactions between plants, soils, and grazing animals. If you graze animals, you already have a grazing system of some kind. As you begin to design or redesign your grazing system, remember that any grazing management problem usually has many possible solutions, and very few things you can do are "right" or "wrong." Most of all, remember than no one grazing system is "best."
By addressing a few simple principles, most grazing management problems can be solved. The successful grazing plan creatively combines these principles specifically for your operation's unique circumstances. Your grazing system will be your particular way of managing your plants, soils, and grazing animals.
A variety of grazing systems have been used on rangelands in the western United States and Canada. Follow the links below to learn more about each system:
- Rest-Rotation Grazing
- Deferred-Rotation Grazing
- Seasonal Suitability
- Best Pasture
- Short Duration Grazing
- Continuous Grazing
Rest-Rotation Grazing The rest-rotation grazing system was designed by Gus Hormay of the U.S. Forest Service and was first implemented in the 1950s and 1960s. Under rest rotation, one or two pastures are rested the entire year while the remaining pastures are grazed seasonally, depending on the number of pastures and herds. For example, one pasture in a three-year, three-pasture rest rotation might be managed as follows during a three-year cycle: 1) graze the entire year or growing season; 2) defer until desirable forage plants set seed, then graze; and 3) rest. This schedule rests about one-third of the range annually.
- Advantages: Rest provides an opportunity for vegetation and soils to recover and helps meet multiple use objectives such as providing hiding cover for birds and forage for other wildlife and leaving ungrazed areas for public viewing and enjoyment. Rested pastures provide forage for emergency use during drought and provide opportunities to implement relatively long-term rangeland improvement practices — for example, burning, reseeding, brush control — during scheduled rest periods.
- Disadvantages: Elk or other wild herbivores may graze rested pastures, negating some of the benefit of rest or deferment from livestock grazing. The increased stock density in grazed pastures can reduce dietary selectivity of livestock and decrease their overall diet quality.
The benefits of a full year of rest can quickly be nullified if previously rested pastures are overgrazed, particularly in arid regions where frequent drought conditions can impede rangeland recovery.
Deferred-Rotation Grazing The key feature of deferred-rotation grazing is that each pasture periodically receives deferment until seed set. Systems can vary in the number of pastures and the length of time between deferments (usually 2 to 4 years).
Seasonal Suitability. Seasonal suitability grazing systems attempt to partition and manage diverse vegetation types that differ due to elevation, ecological site, ecological condition, or precipitation, and to move animals based on seasonal forage production. This system allows managers to strategically move grazing animals to take advantage of forage when it is abundant and of high quality. For example, in southwestern deserts, seasonal suitability systems use creosote bush and mesquite shrublands during winter and early spring, while tobosa grass and alkali sacaton ranges are used during summer. In other areas, livestock may be rotated through native range in the summer, crested wheatgrass in the spring, and Russian wildrye pastures in the fall. Seasonal suitability also has been used on mountain ranges in the northwestern United States where grassland, forest, and meadow vegetation types provide late spring/early summer use, late summer/early fall use, and fall grazing, respectively. Seasonal suitability has been practiced where desert (winter use), foothill (spring use), and mountain ranges (summer use) are managed as separate, seasonal grazing units.
The Best Pasture System The best pasture system attempts to match animal movements with irregular patterns of precipitation and associated forage production. Precipitation patterns may be spotty and unpredictable. Therefore, areas separated by only a few miles may differ greatly in forage production. The best pasture grazing system has no set rotation schedule; rather, it requires that land managers exercise flexibility. For example, when a local rain event causes a flush of annual forbs in a particular pasture, grazing animals are moved to that pasture until desired utilization levels of the ephemeral forbs have been achieved.
Continuous grazing is defined as grazing a particular pasture or area the entire year, including the dormant season, while season-long grazing refers to grazing a particular pasture or area for an entire growing season. Stocking rate is key to the success of a continuous or season-long grazing plan. Stocking at light rates during the growing season is particularly important in continuous grazing systems to ensure adequate forage is left to carry animals through the dormant season. Light stocking rates enable animals to be highly selective in the plants they consume, resulting in a higher quality diet. Furthermore, livestock are not subjected to the stress of frequent moving to new pastures, which can decrease production. Continuous or season-long grazing works best on flat areas with well developed water systems — that is, watering points no more than two miles apart — and where most of the plants have some value to grazing animals.