The region | Effects of climate | Managing for
drought | Land Management tools |
The cattle grazing industry in the North East Queensland region
is rather more diverse and complex compared to others in the
tropical savannas. This is because of the variation in soil type,
average annual rainfall and rainfall variability, all of which
impact on land types, vegetation and pasture communities. It is no
surprise then to discover that there is a whole spectrum of cattle
grazing enterprises, ranging from traditional, extensive systems in
the west of the region, to more intensive, smaller operations on
sown pastures in more fertile areas. The region has some of the
most fertile soils to be found in the tropical savannas. Operations
on these land tracts can be much smaller yet still productive and
sustainable. While there are some properties of considerable size
running tens of thousands of cattle, on average enterprises in this
region are smaller in area compared to others in northern
Australia.
In terms of grazing management, there are several factors which to
some extent set this region of the savannas apart from the rest.
These include climatic variability, issues of soil health and
stability and costs versus benefits of land clearing.
Outside of drought events, there is a general climatic
variability in terms of total rainfall, and the seasonality of
rains. In the south of the region, significant falls of winter rain
may occur, but cannot be relied upon. Total rainfall across the
region is relatively high and ranges from 1200 mm to 400 mm in the
far south west. The majority of the area's rainfall totals falls
between 600 and 800 mm per annum.
In December 1999, only 1 per cent of the total area of
Queensland was declared drought affected. However, for much of the
1990s, apart from a couple of years of above average annual
rainfall, most of this region was declared drought affected.
Markets were also depressed over much of this period, which
disinclined producers to sell livestock. High stocking rates were
therefore maintained on many properties throughout these dry years
over the late 1980s and early 1990s, and only recently have rates
started to fall to what are considered more sustainable levels
(Quirk, M., Ash, A.J., McKillop, G. 1996).
Producers were able to maintain these high stocking rates
because of a number of developments which occurred within the
industry. Some of the developments included changes in cattle
breeds from traditional British shorthorn varieties, to the more
resilient and drought tolerant Bos Indicus .
Supplementary feeding, in which herds are supplied with
phosphorous and proteins lacking in the native pastures, especially
during dry years, increased capacity of animals to consume and
utilise available forage. In effect, this meant that land which
under drought conditions would have had to be destocked in the
past, would continue to be subject to grazing. However, the price
for maintaining these high stocking rates was a general, and
sometimes severe, decline in land and pasture condition across the
region.
The incidence of drought across this region is between one and
two events every 10 years. The regularity of these events, and the
strong chance of them occurring even more often, means that
producers must factor drought years into their long-term management
plans. Some of the ways this is done include:
- flexible stocking rates (buying/selling animals depending on
land condition)
- maintaining supplies of hay
- herd management, i.e. numbers of breeders, timing of breeding
(which will mean that calves are not born when there is little food
about) weaning and pregnancy diagnosis (which allows producers to
cull poorly performing cows)
- sell normal yearly turn-off in February/March instead of
April/May
Many suggest that selling of at least a percentage of the herd
is a better long-term strategy for dealing with drought once it has
kicked in, rather than supplementary feeding, which may assist in
short-term productivity but threaten land/pasture condition in the
longer term. (See for example John Bertram's DPI Note on
supplementary feeding on the DPI Notes website listed below.)
An important aspect of drought management is monitoring land
condition and its response to stocking rates under given climatic
factors. Various packages are now available to assist producers in
decision-making, which require ongoing monitoring of land and
pasture condition. These can be used in combination with herd
management and climate prediction packages.
There are also more accurate climate indicators available, such
as the SOI (Southern Oscillation Index), which reflect fluctuations
in the sea surface temperature, and thus the likelihood of El Nino
events. A positive SOI value, for example, may suggest that the
chances of average rainfall occurring over the next three months is
70 per cent. A low SOI might change this probability to only 30 per
cent.
Late in 1999 SOI readings indicated that chances of higher than
usual rainfall were very strong, and indeed the monsoon trough went
far further south than usual, dumping plenty of rain as it went.
The number of tropical lows, which bring rain to the region over
the summer months, was also much higher than usual over the
1999-2000 summer. So although this indicator is not 100 per cent
precise, it does provide some indication of what to expect, and as
such assists in longer-term property management planning.
Computer programs such as 'Rainman' or 'Droughtalert' can be
used to integrate climate information with grazing management
strategies. In combination with valuable local knowledge and
experience, these tools are improving predictive capacities as well
as integrating various aspects of grazing management.
