Soil Management for Pastures and Rangelands
Pasture Grazing Systems
A grazing system is a particular way of managing the interactions between plants, soils, and grazing animals. When properly implemented, a grazing system can help ranchers and farmers achieve management objectives related to livestock production and sustainable soil management. Selection of the right pasture 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. Developing and implementing a grazing plan forces one to consider the economic and ecological consequences of different management decisions and alternatives. Some of the more popular grazing management systems used by producers include continuous, rotational, strip, management intensive grazing, or high stock density grazing.
Continuous Grazing
In a continuous-grazing system animals are allowed to have unrestricted, uninterrupted access to a specific unit of land throughout the entire or part of the grazing season. This is often referred to as the open gate method where all gates on the farm are open and cattle have access to every field. In a continuous-grazing system livestock have a tendency to graze selectively, choosing their favorite species first and grazing them harder and more frequently while avoiding less desired species. This selective grazing is exacerbated when livestock have access to larger grazing areas and are not rotated frequently enough.
Rotational Grazing
Rotational grazing can mean many things but generally means dividing the pasture into sub-pastures typically called paddocks. Rotational grazing allows a producer to better manage forage in a pasture, but requires more labor than continuous grazing systems. There may be only a few paddocks and livestock are moved every two to three weeks or there could be many paddocks and livestock are moved every few days.
Strip Grazing
This technique involves utilizing a movable, electric fence to allot enough forage for a short time period and then moving the fence forward providing a new allocation of forage. Typically, no back fencing is used in this method, and thus grazing should start in the area nearest to the water source to reduce waste due to trampling. One drawback to this method is that animals are continually crossing back and forth across the same ground as they come and go from water, which can increase the chances of soil compaction, especially near the water source.
Management Intensive Grazing
The goal of management intensive grazing (MIG) is to improve forage production by maintaining enough of a plant’s leaf area to foster healthy above and belowground growth. Management intensive grazing accomplishes this using time-controlled grazing (i.e., short grazing periods of 1 to 3 days) coupled with moderate degrees of defoliation (50% or less) and periods of rest ranging from approximately 21 to 40 days. The stocking rate is very high within one paddock (high grazing pressure) and overgrazing can occur rapidly.
High Stock Density Grazing
Sometimes intensive grazing is taken to an extreme level through high stock density (HSD) grazing, commonly referred to as mob grazing (sometimes known as tall-grass grazing), where extremely high stocking densities are used for very short time periods (from 1-3 days, for example), and consuming 50 percent or less of available forage. This approach is used as a soil amelioration technique, where animals suppress or kill poor quality plant species and with their hoofs help to reseed the paddock with more productive species.
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