Novelly, P. E. (Agriculture Western Australia, Kununurra); Agriculture Western Australia Kununurra District Office; Meat Research Corporation (Australia)
Grazing systems; Grazing trials; Beef cattle; Range management; Range pastures; Range condition; Forage plants; Soil types; Soil analysis; Farm management; Sustainability
The potential cattle carrying capacity of Kimberley rangelands has been reduced from an estimated potential of around 1 million cattle units by as much as 30 to 40% as a result of declining range condition. However, while cattle numbers were undoubtedly excessive in some areas, the area of severely degraded and eroded rangeland in the region is relatively small. While some pasture types are defined as being in poor range condition, others pasture types remain in close to pristine condition. An analogous situation exists in parts of the Northern Territory, particularly the Victoria River District. Uneven cattle grazing patterns are commonly associated with reduced carrying capacity. Some preferred pasture types are constantly overgrazed, other pasture types are only lightly used. Concentrations of feral animals exacerbate the problems associated with this preference for one community or species over another. Therefore the impact of this localised degradation is often a symptom of more fundamental problems associated with uneven grazing patterns. Yet, since localised areas of degradation occur within larger good condition areas its impact is wider, and severely reduces the ability to graze the total area. Moreover, isolation of degraded areas merely moves the problem to another locality, as the fundamental problem of spatially uneven grazing pressure remains unresolved. Under extensive grazing systems, stocking large paddocks at the carrying capacity is only the most preferred pasture type, foregoing the carrying capacity of the often much larger but less preferred types avoids the problem. This strategy has a high opportunity cost in a large proportion of seasons. Another alternative is to fence along pasture type boundaries, and so permitting each pasture type to be stocked at its own capacity. But, both initial capital expenditure on fencing and on-going maintenance are expensive. Since the gross value of per unit area of the rangeland is low, neither of these options is readily adopted by land managers. Concurrently, in terms of its future potential productivity, the rehabilitation of very poor condition or degraded rangeland is often uneconomic. This encourages prevention of degradation rather than rehabilitation. A preferred option to addressing this problem, and one that may be more commercially acceptable to managers, would be modify the cattle grazing distribution to the extent possible by low cost means, and so making forage use more uniform across the landscape, while concurrently monitoring the grazing impact on the more preferred pasture types to ensure that they are not being overused. By partially mitigating the effects of spatially uneven grazing pressure and strategically spelling areas based on identified soil and vegetation indicators, a more uniform and sustainable grazing pattern would exist, permitting more profitable and sustainable production. Moreover, a more uniform cattle grazing pattern could improve cattle diet, and hence cattle performance. Therefore, the long-term economic sustainability of the extensive cattle industry could be improved through the better management of the rangeland resource.
