Redesigning Animal Agriculture

174 I. Gordon and B. Nelson
cultural industries (particularly banana)
have undergone considerable expansion in
the coastal catchments (Gilbert et al., 2003).
The use of herbicides and pesticides is
also significant in areas of crop cultivation
(Hamilton and Haydon, 1996) with negative
effects on corals and marine vertebrates
(Hutchings and Haynes, 2000).
But it is the grazing industry that accounts
for the majority (over 80%) of terrestrial
sediments and nutrients deposited in
the GBR (Gilbert et al., 2003). The Burdekin
catchment, where the primary land use is
grazing, delivers on average 3.8 million
tonnes of fine sediments, 8600 tonnes of
nitrogen and 1300 tonnes of phosphorous
per annum into the lagoon of the reef. The
figures for the Fitzroy are 2.9 million tonnes
of sediment per year exported to the coast,
in addition to 8000 tonnes of N and 2000
tonnes of P (Brodie et al., 2003). Present-day
export of sediments and phosphorus from
these catchments is six times, and nitrogen
four times, greater than pre-European levels
(Brodie et al., 2003).
The quantity of sediments and nutrients
lost from these grazing lands depends strongly
on grazing management practices such as
stocking rate, tree clearing and positioning
of watering and supplementation points
(McIvor, 2002). Poor grazing management
practices are often exacerbated by drought,
which leads to degradation of soil and water
resources. These include impaired soil biological
function, depletion of organic matter
and reduced nutrient-holding capacity, soil
acidification, erosion, compaction and rising
water tables and salinization (Gifford,
1985). Ultimately, excessive sediments and
nutrients flow into the coastal waters of the
lagoon of the reef and have a negative impact
on corals reefs (particularly near-shore reefs)
and seagrass beds, with consequences for the
fish assemblages (Fabricius, 2005).
Because of these environmental effects,
graziers have been under pressure to change
their management practices to decrease offproperty
environmental impacts (see Anon.,
2003). Soil and vegetation loss through
unsustainable management practices is also
likely to lead to reduced livestock production,
since vegetation acts as a barrier to the
overland flow of water, thereby increasing
ground infiltration (Ludwig et al., 2005).
The variable and unpredictable climate
of the east coast of Queensland (Fig. 10.2) further
exacerbates the problems faced by pastoralists.
A consequence is that graziers will
tend to be over-optimistic about the probability
of rainfall and will maintain stock levels
above those which can be carried over the
dry season, using supplementation to buffer
against reduced pasture resource levels. This
strategy, exacerbated by government drought
relief policies, leads to pasture degradation,
reducing the long-term carrying capacity of
the land.
The preceding background shows that
there are challenges to the grazing lands
of the catchments emptying into the GBR
lagoon. However, recent research demonstrates
that graziers can change their management
practices to decrease the negative
effects they have on the quality of water
leaving these properties. This involves
maintaining high levels of ground cover and
increasing the amount of water, sediments
and organic matter captured by vegetation. In
the long term, this could lead to an increase
in the productivity of the vegetation and,
therefore, the profitability of the enterprise,
through reduced inputs of supplements and
less variation in stock numbers over time.
Grazing Ecology
Beef production in the extensive rangelands
of the GBR catchments primarily relies upon
native vegetation, with some introduced
species of legumes and productive grasses,
to supply nutrition to the animal for most of
the year (Bortolussi et al., 2005). Most enterprise
management is based upon stocking
rate and the timing of purchase and sale of
animals. The extensive beef system typical
of northern Queensland has limited technological
intervention compared, for example,
with the dairy industry, other than the
delineation of paddocks and the positioning
of waterholes (Bortolussi et al., 2005; Stokes
et al., 2006) and the use of nutrient supplements
that are provided to overcome protein