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EnviroNorth > VRD-Sturt > Grazing > Grazing management issues in the Sturt Plateau

Grazing management issues in the Sturt Plateau

Grazing management issues of the Sturt Plateau are quite distinct from the Victoria River District. The plateau is at present characterised by ongoing subdivision of large extensive leases (around 2000 square kilometres) to smaller ones (around 600 square kilometres). The majority of the original properties have now been subdivided to some extent. Many of these newer properties are in the earlier stages of development, and stock numbers are limited by lack of infrastructure including fences and bores. However, as development proceeds, herd sizes are increasing.

While the majority of enterprises run cattle on native pastures, there is a trend toward developing more intensive grazing systems based on improved pastures and other crops. The area has seen some clearing to this end, although limited roads have restricted horticultural options mainly to grain and hay cropping. The provision of land for agistment, and short-term 'depoting' of live export cattle on route to Darwin, represent additional income sources for plateau producers.

Constraints

Property viability is determined by debt levels, management ability, off-farm income and property size. Given the limited development of infrastructure on the plateau, capital is especially important. Those pastoralists with more capital, or less debt, are therefore better positioned to develop their properties to a self-sustaining level of production.

The effort and capital required to reach sustainable production levels may have contributed to the high rate of property turnover, although rising land prices have resulted in significant property speculation also.

A further constraint is the dearth of research into various issues on the plateau. Knowledge of pasture communities and carrying capacities for example is limited. However, groups such as the Sturt Plateau Best Practices Group and the Northern Territory Department of Lands, Planning & Environment Land Use Development and Management Strategy are in the process of redressing such imbalances.

Ground and surface water

While this region has been identified (Day 1985) as having the potential to intensify agricultural production, a number of constraints remain, limited water and complex access to groundwater in particular. As a result, stocking rates have traditionally been maintained at a low level.

Groundwater throughout the Sturt Plateau is mainly exploited from within aquifers developed in the fractures and cavities of the region's extensive limestone formation.

The availability of groundwater over the majority of the plateau however has been a complex issue. The interaction of the geology and a moderately deep water table (greater than 50m from the ground surface) usually determines the suitability of environments for aquifer development. Depending on these conditions, groundwater prospects vary and may range from excellent, particularly in the north-western sector and along the eastern flank, to poor in the central region.

Surface water options are limited on the Sturt Plateau. Bores currently supply the vast majority of the water needs with a supplement coming from waterholes where they exist. Where bores are used, steel tanks serve as temporary storages. During the wet and the early dry season, most of the available surface water that is accessible is used, but as the dry season progresses, these sources become depleted. Many waterholes within the Western Creek system and the black soil areas developed on the palaeo channels of the Dry River persist throughout the year.

While knowledge of where to find water for bores has increased, this kind of property development, along with fencing, can be extremely costly.

Land systems

Average annual rainfall on the Sturt plateau ranges from 780mm in the north to 590mm in the south. Reliability of rain is fairly high over much of the plateau, although declines south of the Murrangi stock route. Soil types range from very light sands through to poorly drained soils, to extensive wide valleys of red earth soils and limited areas of black soils.

Major pastures in the south of the region include spinifex (Plectrachnepungens and Triodia spp), flinders grass (Iseilema spp.) and some mitchell grass (Astrebla spp.). However the majority of the plateau supports pastures incorporating Sorghum spp., black spear grass (Heteropogoncontortus) and ribbon grass(Crysopogonlatifolius) on areas of heavier soil. Black soil country, while limited in area, is the most productive on the plateau. It is found along relic watercourses and old floodout areas and supports pastures including ribbon grass (Crysopogonlatifolius), bluegrass (Dicanthiumfecundum), silky browntop (Eulaliaaurea) and mitchell grass (Astrebla spp.).

Compared to other grazing regions, the Sturt plateau is relatively weed free. There are limited infestations of bellyache bush (Jatrophagossypifolia), devil's claw (Martyniaannua), hyptis (Hyptissuaveolens) and Sida spp. The spread of weeds however will probably increase as the area becomes more populated and developed.