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.
