A Revolution in Land Use
Report Card
Annual cropping
Opportunity cropping
Phase/companion farming
New agricultural plants
Organic farming
Perennial pastures
High rainfall tree products
Low rainfall tree products
Agroforestry
Saltland farming
Report Card
This section reviews the options described in the previous pages on the
basis of four criteria:
- relevance to the Basin in terms of the area of suitable land
- effectiveness in terms of each option's ability to reduce leakage
- robustness in terms of the ability of land users to achieve the potential
in (2) above, and
- profitability relative to current land use.
Ten broad options are rated in Table 1. The rainfall limits on forestry,
perennial pastures and cropping are more flexible than suggested in Figure
22 and Table 1, yet rainfall still imposes severe limits on the relevance
of an option.
Figure 22. Proportion of the Basin in different rainfall classes.
Effectiveness depends on the perenniality and rooting depth of the plants
in each system. The long-term average leakage from the system is determined
by the proportion of land under perennial vegetation and the ability of
this vegetation to use water. Options that are potentially effective may
not be robust enough to obtain a desirable outcome due to the lack of
required technology because rainfall variability makes them difficult
to manage. Where we consider effectiveness to be low, we do not give robustness
a rating. Profitability is relative to current land use.
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Annual cropping
Cropping rates 'high' (see Table 1) in relevance and profitability
because of the large land area under crop and its status as the preferred
economic option. However the effectiveness of annuals in attaining recharge
targets is low.
Opportunity cropping
Opportunity cropping is profitable, robust and moderately effective
where summer-dominant rainfall coincides with soils that have high water-holding
capacity (e.g. the northern parts of the Basin). However, it has a lower
rating on relevance since such areas represent only about one third
of the cropping zone.
Phase/companion farming
Phase farming is effective when the lucerne phase is long enough to
dry the subsoil and the cropping phase is terminated before leakage
recommences. Its relevance is rated as medium because lucerne is limited
to areas with suitably deep non-acid soils. The robustness is medium
because it depends on the land manager's skill in timing the change
of phase. Profitability is likely to be reduced in phase farming due
to the lower average returns from animal production in the lucerne phase.
Oversowing annuals into perennial pastures is emerging as a variant
of phase farming that may be more effective and robust, but it might
also have productivity trade-offs. Further investigations are needed.
New agricultural plants
New crops or forages that restrict drainage may be moderately effective
and are potentially profitable components of new farming systems.
The relevance and robustness of such species and/or cultivars are
unknown at this stage, and depend largely on the success of the plant
breeders in developing new cultivars with novel characteristics.
Table 1. Options for managing dryland salinity.
Organic farming
Organic farming is not necessarily any more effective than annual
cropping. However, the rapidly growing demand for organic produce,
particularly from overseas markets, means this is an increasingly
relevant option. If good prices can be maintained for organic produce
then profitability could be high. Profitability combined with the
land stewardship ethic that characterises the organic farming movement
could translate into a larger area of any one farm devoted to non-commercial
vegetation that is high in water use.
Perennial pastures
Perennial pastures use more water than annuals, but they are
not necessarily effective in the grazing zone east of the cropping
belt. Higher rainfall, acid and shallow soils and grazing pressure
all compromise their potential. The moderate profitability of
the grazing industry limits investment in liming, pasture improvement
and grazing management, thus reducing the robustness of this
option. The shallow roots of perennial grasses compared to lucerne
or woody perennials may thwart attempts to make annual crops
perennial through genetic manipulation.
High rainfall tree products
The strategy of developing high rainfall tree products is profitable,
but its relevance is low, simply because the proven range of
products is limited to a very small area of the Basin. The effectiveness
of this strategy in reducing leakage is better than for any
other land use. However, some high rainfall catchments are already
flushed of salt, making them more valuable as contributors of
fresh water in their cleared state.
Low rainfall tree products
Developing low rainfall tree products is potentially the most
relevant, effective and robust land-use option for managing
salinity. However, with the exception of a few niche industries,
low rainfall forestry does not exist in a commercially viable
form. The major obstacle is finding markets of sufficient size
and value to drive reforestation and the use of native plants
at the necessary scale. The transition from a fossil fuel to
a bio-fuel transport economy is the scale of change required
for this to happen.
Agroforestry
In the absence of forestry that is as profitable
as cropping, the careful location and arrangement of trees can
increase their water access and growth rates and minimise the
displacement of more valuable crops. Tree/crop mixtures are
therefore highly relevant and more profitable than tree crops
alone. Their effectiveness will depend on the area planted to
trees, and on the skill of locating trees in the right parts
of the landscape. Finding trees that are complementarity to
cropping or pastures remains a major obstacle.
Plants use water from saline aquifers at very low rates. As the
area of salt affected land increases, commercial rehabilitation
with salt tolerant vegetation will become important for stabilising
soil and providing stock feed, but it will contribute very little
to managing the watertable, salt loads to rivers, and therefore
to water quality.
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