Grazing does not occur evenly across a whole paddock or property and the tendency for animals to graze some areas and plants rather than others has important implications for long and short-term carrying capacity and grazing management.
The four main reasons why livestock do not graze a paddock evenly are:
- Distance to water.
- Patch grazing.
- Land type preference.
- Plant species preferences.
Distance to water
In extensive grazing operations, distance to water can have a major affect and result in what is known as a grazing gradient. This term describes the situation where overgrazing occurs near the watering point while pasture remains underutilised away from the watering point. In the case of cattle, while they will walk up to 10 km from water, most of the grazing, up to 80%, occurs within 2 km of water.
Distance to water must therefore be considered when calculating the carrying capacity of a paddock. If paddocks are stocked simply according to paddock size (rather than to the area within an appropriate distance from water), areas close to water will be over-grazed while remaining parts of the paddock will be underutilised.
Patch grazing describes the situation where livestock preferentially graze concentrated areas or patches in a paddock. These areas are then continually grazed as the pasture regrows leading to chronic overgrazing in those areas while leaving other areas rank and unutilised. This makes determining a safe carrying capacity for the paddock difficult.
If left unchecked, continual patch grazing can result in the loss of palatable species in the grazed areas, weed invasion and even the development of scalds and erosion.
Patch grazing can be managed with burning, the spelling of affected paddocks and fencing.
Land type and plant preference
Livestock will always graze some species and land types in preference to others and it is important that grazing pressure be managed to prevent preferential species and areas from being overgrazed.
Similarly, livestock tend to prefer particular areas and land types over others. Grazing distribution according to land type preference can be managed to a certain extent through paddock design, such as the positioning of watering points; however, in some cases fencing may be the only way to encourage livestock to modify their grazing behaviour.
Infrastructure and grazing management
Managing grazing distribution is an important part of grazing management. This can be achieved by strategically positioning watering points and through the strategic fencing of land classes and vulnerable areas.
Other techniques for attracting livestock to under-utilised areas within paddocks include the strategic placement of feed supplements away from heavily grazed areas, improving the attractiveness of the vegetation through fire or slashing and creating pathways by slashing or grading livestock.