above measures of performance are useful financial analyses. However,
maximising profit may not be the best solution particularly in the
short run, but rather, the farmer should look at sustainable
agriculture over the long run. It is possible to exploit the inherent
features and fertility of agricultural land so as to enjoy large
short run profits, for example, by overgrazing. However, if the
farmer does this he/she will lose in the long run because the
property will suffer damage such as soil erosion which will reduce
gross margins over the long run.
agriculture is agriculture which maximises profit over the long run.
That is, agriculture which preserves the soil's structure and
fertility etc so that the farmer enjoys year in year out profits and
the farm is no worse off after farming than it was before. Such farm
management or good husbandry will preserve the land asset.
increasing concern about the long term condition of the land and
the pressure to get more and more from it makes this one of the most
important questions that farmers can ask. The answer lies in using
the land within its capability. In other words, using the land
without causing permanent damage or a reduction in its future
ensure that the farm system is used within its capability, farmers
must overcome several problems:
- Water erosion
- Decline of
organic matter in the soil and breakdown of soil structure
- Wind erosion
- Decline in
solutions to these problems exist and many farmers have put them into
practice. The following are not an exhaustive list of sustainable
measures but rather, the more common and important ones. The
following are the most common farming techniques used in sustainable
METHOD 1 - CONTROL RUNOFF
from rainfall can be effectively controlled and erosion reduced by
properly constructed and maintained contour banks, waterways and
diversion banks. The value of structures to control run off has
been proved on farms in the northern agricultural district for over
50 years. Most often a combination of structures is required to
control the flow of runoff across cultivated land so that:
- erosion is
- flooding is
- waterlogging is
FOR THE CONTROL OF RUNOFF
design of systems to control runoff should be planned well because
fences, tracks, access and natural drainage lines must all be taken
into account. For best results design run off control as part of
a property plan.
most effective way of controlling runoff is through a coordinated
banks provide simple, effective and long lasting protection from
water erosion. Effective contour banks are:
- Well planned
- Connected to a
well grassed waterway.
bank construction and maintenance costs are low, especially when the
long life of the banks is taken into account.
grassed waterways are an essential part of a run off control
system. Grassed waterways:
- Safely conduct
run off water through cultivated areas
run off water, which helps to prevent flooding and water logging.
catchment grass slopes are known as flumes.
40% (40 000 ha) of the land with a moderate potential for water
erosion in a typical Soil Conservation District was protected with
contour banks by the end of 1991.
METHOD 2 – STUBBLE RETENTION
retention of crop and pasture residues improves long term
productivity and reduces soil degradation. Protection from erosion.
Stubble retention :
- Protects the
soil from wind and water erosion
- Adds organic
matter to the soil, improving soil structure and fertility
- Increases water
- Protects the
soil from raindrop action, reducing soil movement and surface sealing
- Recycles plant
dramatically increase earthworm activity.
2 tonne/ha wheat crop produces about 3 t/ha of stubble and chaff.
When evenly spread, this will provide about 75% ground cover, and
gives adequate protection from water erosion. Less stubble is
required to protect soils from wind erosion. Generally, about 35%
ground cover is adequate. Farmers in the district have successfully
retained stubbles from 4 t/ha wheat crops.
WITH STUBBLE RETENTION
stubbles can be successfully retained provided there is adequate
planning. For example:
- begin stubble
treatment at, or immediately after, harvest. this will allow the most
time for the stubble to break down before seeding or pasture
as much stubble as possible on the soil surface. this provides the
greatest soil protection and a better seedbed. most of the problems
experienced with stubble retention are caused by incorporating stubble
into the seedbed.
stubbles into manageable lengths (usually 15 cm or less). it is the
length of the stubble, not the quantity, that causes blockages in
machinery. avoid repeated harrowing or working just to break up or bury
stubble. the damage these extra cultivations do to the soil structure
outweighs the benefits of keeping stubble.
legume stubbles need careful management as they are highly prone to
erosion. grazing aggravates the erosion risk.
is too valuable to burn. when stubbles are burnt, all of the nitrogen
and sulphur are lost. burn only as a last resort and use a cold burn
after the opening rains.
the stubble from a 2 t/ha Spear wheat crop is burnt about 15 kg of
nitrogen is lost per hectare. This is equivalent to the nitrogen
contained in 34 kg of urea.
METHOD 3 - REDUCE TILLAGE
all farm practices, cultivation is the greatest destroyer of the
soil. Reduced tillage systems limit cultivation and the consequent
soil erosion and decline in soil structure. Reduced tillage results
in improved crop emergence, root growth, crop yield, and overall farm
TO REDUCE CULTIVATIONS:
cultivations with herbicides
- use chemical
topping, spray grazing or slashing of pastures to reduce weed
populations before cropping.
- cultivate only
when weeds are present
- control crop
diseases with appropriate rotations.
degree to which cultivation can be reduced depends on getting other
management factors right, particularly weed control throughout the
rotation. In the light of increasing herbicide resistance, some
cultivation for weed control will be necessary in the rotation. In
the long term, it is the total number of cultivations over the
rotation that is important.
loss of 1 mm of topsoil represents 10 to 12 t/ha. Such losses occur
frequently on bare or sloping soils and often go unnoticed.
METHOD 4 - DIRECT DRILLING
drilling, or the sowing of a crop into unworked soil, is the ultimate
form of reduced tillage. Any weeds present before sowing are
controlled with herbicides. Direct drilling:
- is markedly
superior to other forms of reduced tillage in lifting soil organic
matter and improving soil structure.
rainfall infiltration and minimises erosion
- enables higher
yields through more timely sowing
- reduces the use
of machinery and fuel
- encourages the
proliferation of earthworms.
lost through wind erosion is the most fertile part of the soil.
Concentrations of 60 ppm available phosphorous have been recorded in
dust samples that came from a paddock with an average concentration
of 24 ppm available phosphorous.
METHOD 5 - IMPROVE SOIL STRUCTURE AND ORGANIC MATTER
structure and organic matter are closely related and play a vital
role in preventing soil erosion and maintaining crop production and
overall farm viability. Well structured soils:
- are porous
- are friable
- have stable
soil aggregates or crumbs
- are resistant
to erosion, compaction and formation of surface crust
- allow quick
germination, seedling emergence and root growth
- good aeration
- easy working.
to the way individual soil particles of sand, silt and clay are bound
together. The structure of a soil is influenced by its physical and
chemical properties, its organic matter content and the activity of
matter or humus is formed by the decomposition of plant and animal
residues by micro organisms. In most soils, about 95% of the
nitrogen is present in the organic matter. Only a small proportion of
this is released each year for use by a crop.
- maintains good
- improves the
chemical and biological fertility of the soil
- contains almost
all the soil nitrogen reserves
- is the main
soil binding agent in sandy soils.
METHOD 6 - SOIL STRUCTURE AND ORGANIC MATTER CAN BE IMPROVED
soil structure is a long term process and relies on increasing
the organic matter content of the soil:
- use a rotation
that includes a vigorous legume pasture phase
- reduce tillage
- retain stubbles
- monitor organic
matter through soil tests for organic carbon
- apply adequate
fertiliser to crops
- apply gypsum to
object is to maintain high organic matter levels. Restoring depleted
organic matter is a difficult and long term process.
TYPE, SOIL STRUCTURE AND ORGANIC MATTER
structure and organic matter vary considerably with soil type and
management. Red brown earth soils, particularly those with a
sandy loam to loam surface texture, are highly susceptible to a
decline in soil structure and organic matter.
soils have a low potential for a decline in structure but are highly
susceptible to a decline in organic matter. Calcareous loamy soils
have a low potential for a decline in structure because of their high
lime content. They are prone to a decline in organic matter but this
is often a slow process because they have naturally high levels of
cracking clay soils have a low potential for a decline in structure
and organic matter. This is because of their clay content and
naturally high levels of organic matter.
VIGOROUS LEGUME PASTURES
rotations that include a vigorous legume pasture phase are essential
for the long term well being of the land and for the
production of high yielding crops and high quality grain.
of the variation in rainfall, soil types and rotations across
Australia's agricultural areas a number of different pasture legumes,
including medics, clovers and vetches, have a role.
benefits of a vigorous legume pasture phase:
- improved soil
earthworm and microbial populations
- some reduction
in crop diseases and weeds.
good legume pasture can increase soil nitrogen by more than 80 kg/ha
in one season. This is equivalent to at least 170 kg/ha of urea. Most
pastures consist of annual medics and clovers because of their
ability to regenerate after crops and persist in pasture phases.
- are generally
adapted to neutral to alkaline soils
- are suited to
lower rainfall than are clovers and dominate where the rainfall is less
than 375 mm.
- are well suited
to regular cropping rotations because they have a high proportion of
- are generally
suited to neutral to acid soils
- require at
least 400 mm annual rainfall
- produce fewer
hard seeds than do medics and are therefore less suited to regular
- are well suited
to permanent pastures.
TO GET THE BEST OUT OF ANNUAL LEGUME PASTURES
- when selecting
varieties pay careful attention to farming system, rainfall and soil
texture and ph.
- sow at the
- use mixtures in
paddocks with several soil types
- defer grazing
during seedling establishment
grazing from the onset of flowering and graze judiciously over summer
and autumn to ensure there will be some seed reserves.
- control pests
such as red legged earth mite, lucerne flea and aphids.
that include vigorous pastures provide the highest yields of high
METHOD 7 - PLAN FERTILIZER USE
fertiliser use is essential to prevent the depletion of soil
nutrients through removal in farm products and to improve or maintain
soil fertility for optimum crop and pasture yields. Grain legumes
remove considerably more nutrients than do cereals. For example, one
tonne of peas contains about 39 kg of nitrogen, 3.8 kg of phosphorus
and 2.4 kg of sulphur, while one tonne of wheat contains about 21 kg
of nitrogen, 2.6 kg of phosphorus and 1.6 kg of sulphur.
develop a planned fertiliser program, determine the nutrient status
of soils, crops and pastures by keeping accurate paddock records and
using soil and plant tests. The main nutrient deficiencies that occur
in Australian agriculture are nitrogen, phosphorus and zinc.
deficiency is considered by many to be the greatest constraint to
cereal yields. Nitrogen is also a critical factor for achieving
adequate protein levels in wheat grain. To overcome a nitrogen
- in the short
term, apply nitrogen fertiliser
- in the long
term, increase the reserve of nitrogen rich soil organic matter
through vigorous legume pastures.
Australian soils are deficient in phosphorus in their natural state.
Regular additions of phosphate fertiliser are required for maximum
growth of crops and pastures.
deficiency commonly occurs but in varying in degrees with soil type
and management. The most reliable method for identifying zinc
deficiency is to tissue test crops and pastures.
METHOD 8 - REHABILITATION OF SALTLAND
prevention and rehabilitation of dryland salinity requires a
catchment approach to water use. The main issues are:
- prevention of
ground water recharge on unaffected areas
productivity on affected areas.
aim is to minimise the amount of ground water recharge by maximising
water use. Dryland salinity is caused by changes in water use that
have occurred since European settlement. deep rooted perennial
vegetation has been replaced by shallow rooted annual plants
that use less water. Groundwater levels rise, mobilising salt stored
in the landscape. Where this water gets within I to 2 m of the soil
surface, saltland develops.
- use crop and
pasture species that use a lot of water such as lucerne
high yielding crops and pastures to maximise water use
perennial vegetation either agricultural or native species on land of
low productivity such as rocky outcrops, paddock corners and laneways.
LAND THAT IS MODERATELY SALINE:
- Use salt
tolerant crops such as barley
surface cover at all times to prevent salt from concentrating at the
LAND THAT IS HIGHLY SALINE:
is, too saline for broadacre crops:
the ground water is too saline for lucerne, establish and maintain
pasture using salt tolerant species, such as tall wheat grass,
puccinelia, strawberry clover and saltbush.
grazing so that surface cover remains at all times to prevent salt from
concentrating at the soil surface.
structures to control water run on from adjacent areas
salt tolerant native trees and shrubs to increase water use.
METHOD 9 - CONSERVE AND ESTABLISH NATIVE VEGETATION
REMNANT NATIVE VEGETATION
of the original native vegetation, including mallee scrub, shrublands
and open grasslands, have removed for agricultural development.
Grazing, burning, fragmentation and isolation, and invasion by
introduced plants and animals has degraded much of what remains.
Sound management of the remaining native vegetation is essential to
ensure that regeneration occurs:
- fence to
- control animal
and plant pests
- on grazed
areas, control grazing pressure to enable regeneration
- enter into
heritage agreements with the appropriate department.
vegetation can improve agricultural production and should be
established wherever possible, for example:
- for the
protection of crops, pastures and livestock
increase water use on areas of low productivity such as rocky reefs,
shallow soils and paddock corners, and on and around saline areas and
areas prone to waterlogging.
stabilise erosion gullies
woodlots, honey and amenity purposes.
native trees, even when dead, are especially important as more than
one quarter of native bird species use tree hollows for shelter
METHOD 10 - STABILISE SANDHILLS AND SANDY SOILS
and sandy soils that are associated with the dune swale system
on the coastal plains are highly prone to wind erosion. Increasing
the stability of these soils will reduce the risk of wind erosion:
- Maintain ground
- Minimise soil
- Improve soil
fertility and organic matter
- Match crop type
to the capability of the land
- Control root
- Plan the layout
of property improvements
sandhills are best fenced off and used for permanent pasture but an
occasional crop may be necessary to reclaim eroded areas, improve
soil fertility, control weeds or renovate pastures:
- sow with a
cereal crop that will provide good ground cover, for example cereal
rye, barley or triticale.
- sow sandhills
at the start of the cropping program
- use adequate
amounts of nitrogen and phosphorous fertiliser
- resow as soon
as possible if wind damage occurs
- use minimum
tillage or direct drilling
- retain crop
stubbles and pasture residues and control grazing to maintain at least
70% ground cover.
METHOD 11 - PLAN THE PROPERTY
land should be used within its capability so that it is in as good
as, or better, condition for future generations. The best way to
achieve this is to develop and implement a property plan. Property
planning involves consideration of all the components of the property
including climate, topography, soil, native vegetation, property
improvements, crops and livestock, pastures, economics and personal
goals, and their integration into a profitable, sustainable and
efficient farming system:
- assess the
resources of the property and the capability of the land
- plan the best
arrangement of property improvements
- identify the
land use and management options to which the land is suited
- establish a
financial plan, priorities and a work program to implement the plan.
conservation boards encourage land holders to prepare property
plans, and are authorised to approve property plans provided they
conform with their district plans.
OF LAND CLASSES AND THEIR MANAGEMENT
with a potential for wind erosion:
management of minimum tillage, stubble retention and a rotation that
includes a pasture phase.
management, with crops restricted to cereals and, on average, a
rotation with no more than one crop in two years.
the capability of the land is the first step in property planning.
Eight land classes are used to rank agricultural land from highest to
lowest capability. The capability of the land, and therefore the land
class into which it is placed, depends on the nature and severity of
the limitations present (for example water erosion potential, wind
erosion potential, rockiness and salinity). Examples of land classes
and their management.
OF LAND CLASSES AND THEIR MANAGEMENT
with a potential for water erosion.
management of minimum tillage, stubble retention, and a rotation that
includes a pasture phase.
management plus contour cultivation
management plus contour banks, waterways and reduced use of grain
IV Improved pasture
and controlled grazing to maintain
Vl Non arable
because of rockiness and steep slopes. Grazed carefully to maintain
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