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Environmental Factors Affecting Australia's Livestock Industries
Livestock industry development has had significant and prolonged impacts on Australia's environment. At the same time, the industry is affected by environmental issues and is adapting to meet pressure for change. The severity and scale of problems has changed over time. Some problems have been slow to emerge and are now being addressed as national priorities.
Clearance of vegetation for agricultural and pastoral development has changed the balance of vegetative cover and lies at the root of many environmental problems. Pasture improvement has been a 'driver' of land clearance. It accounted for 50% of land cover change between 1990 and 1995 and for 86% of total clearing in Queensland between 1995 and 1999. Clearing for pastures increased from 1950.
Clearing has been a major source of greenhouse gas emissions ascribed to land use change. It also affects biodiversity, but detailed measures are not available. Controls have been introduced as a response to continuing and extensive clearing, notably in Queensland where the government has introduced a Vegetation Management Act. Vegetation management plans are providing guidelines for control of further clearing and other measures to reduce clearing and its effects are being prepared with industry consultation. Some net greenhouse benefits may be obtained from control of woody weeds.
Proposed methods to reduce greenhouse gas emissions from livestock need careful assessment. Cyclical reductions in livestock numbers have reduced emissions but further reduction in animal numbers is an unlikely source for emission targets. Research continues into the reduction of methane emissions and other emissions that can be associated with the livestock industry. Improving the quality and management of feedstocks may reduce methane emissions. Nitrous oxide emissions from extensive dryland pastures are lower than emissions from irrigated pastures, and better management also can reduce nitrous oxide emissions. One strategy being developed is flexible trading of emission permits and the impacts of emissions trading may differ across the industry. The industry will have a major interest in how controls and permit trading systems are developed.
The use of fire as a pasture management tool has a complex relationship to the greenhouse issue. The benefits of increases in soil carbon may be offset by increased gas emissions. Overgrazing, often exacerbated by drought, has a major impact on soil carbon storage in rangelands.
Climate change predictions indicate the potential for some improvements in the productivity of rangelands, but increased variability and greater extremes of rainfall together with other negative impacts will drive adaptation of grazing practices.
The clearing of vegetation also is a direct cause of soil acidification. Leguminous crops and pastures, fertilisation, removal of products and burning-off all contribute to acidification. Increasing acidification is associated with aluminium toxicity to plants. Acidification depresses activity of microorganisms and causes physical and chemical changes. It progressively reduces pasture productivity and has also reduced species diversity. To date, acidification has not been shown to affect water resources in Australia. Natural rates of acidification are low. Estimates of hazard show that some soils will degrade rapidly under annual pasture regimes. Acidification has mainly affected southern Australia but it can occur in the north. Very severe acidification has occurred under improved pastures in the south. Introduced species have contributed to nitrate leaching in the north. Sixty percent of soils in the intensive land use zone have a pH of less than 5.5. Addition of lime may be a cost-effective solution only for intensive grazing and current plant breeding programs are unlikely to provide a sustainable alternative solution for acidification.
Salinisation is Australia's most costly and serious environmental problem and clearing of native vegetation is its primary cause. Introduced crops and pastures have changed the water use regime and salinisation can emerge a long time after land clearing. Groundwater rises and salt accumulates where shallow rooted, introduced species cannot use the available water. The area of land affected is predicted to treble in the next 50 years. Increasing water quality problems result from saline groundwater discharge. Some groundwater supplies for stock and irrigation are at risk from increasing salinity. The National Land and Water Resources Audit has reported major increases in the salinity of rivers and streams.
Impacts on urban water users and infrastructure may be blamed on graziers. Concern about salinity will put pressure on the livestock industry to change land use. Salt load targets in the Murray-Darling Basin also will force land use change. Graziers in high-risk areas are likely to incur losses from rising groundwater and from measures to prevent it. They will need to receive better information and to sustain a strong commitment to adoption of best management practices.
Grazing and cultivation for fodder crops have had a marked impact on soil structure. Soil structural degradation is due to changes that affect aggregation, water infiltration, shear and tensile strength, bulk density, porosity and water storage. Trampling is also a factor in structural decline. It is highly probable that structurally many soils were in significantly better structural condition prior to European settlement than they are today. Decline is often slow, but its impacts are wide ranging. The estimated affected area is nearly 26 million ha across all States.
Field evidence is increasing scientific understanding of the effects of structural decline. The role of low ground cover is important in the recovery from structural damage in sensitive environments. Adoption of "best management practices" can minimise structural decline and its effects.
Sustainability has replaced infrastructure development as the driver of water policy. The livestock industries are major users of Australia's water resources and they have had major impacts on landscapes and landscape function across Australia. The establishment of productive pastures after clearing of deep-rooted native species affects the water budget on the land surface.
Pastures consume approximately 35% of total water and stock and domestic supplies account for 8%. Water use by the livestock industries and other farming enterprises affects downstream users. Extensive grazing and irrigation for the livestock industry is a diffuse source of pollution. Livestock industries are often associated with the addition of fertilisers, pesticides, herbicides and other chemicals to the land. Overgrazing can result in increases in stream turbidity, salinity and faecal contamination. Turbidity is a worsening water quality issue across Australia. Contamination of surface waters, erosion of river banks and increases in stream turbidity are attributable to stock access.
Agriculture is usually the prime source of nutrients and pesticides causing algal blooms, but high stocking densities and irrigation frequency in the dairy and beef industries creates opportunity for algal toxins to accumulate. The problem of nutrients in riverine systems is exacerbated by several factors, including animal manure. Nutrients are a major surface water quality issue across Australia in more intensively developed areas including areas used for cropping, dairying and other livestock industries.
Surface water resources dominate the water use by the livestock industry. The livestock industry has had greatest impact on surface waters, stream habitat and downstream users in the Murray-Darling Basin and the Goldfields and South-West regions of Western Australia. The availability of surface water impacts the livestock industry over a substantial part of the country but groundwater supplies are generally sufficient.
The groundwater resource base will not limit the overall expansion of the livestock industry but over-allocation has occurred in some areas. Ten percent of the groundwater that is suitable for potable, stock and domestic use and for irrigated agriculture is currently used.
The most important groundwater supply is the Great Artesian Basin (GAB) and it is damaging to the industry to be associated with excessive water wastage and environmental degradation resulting from inefficient water use. The industry uses most of the water extracted from the GAB. Extensive water reticulation systems in the GAB are old, and numerous artesian bores are allowed to run freely which has meant that in excess of 90% of water extracted has been wasted. Groundwater pressures are declining over significant parts of the Great Artesian Basin. Environmental, biodiversity and sustainability issues related to water use in the Basin also have implications for inter-generational equity.
Mound springs in the GAB are strategically and ecologically important and have been subjected to grazing of various intensities, and to trampling and compaction of their margins with adverse effects. Falling groundwater pressure is primarily a result of water extractions by the pastoral industry. Recognition of groundwater dependent ecosystems as having high conservation value is developing, and the industry should look towards measures for their preservation as issues arise.
During the past decade groundwater quality assessment has included additional factors such as nutrient, toxic chemical, trace elements and microbiological loads. Broad area sources, such as grazing, dairying and animal manure applications have the potential to affect groundwater resources with widespread contaminant loads.
Studies have shown that there are elevated nitrate concentrations in the groundwater across the nation in areas of grazing and dairying. On occasion, pathogenic viruses, bacteria, and protozoans of gastrointestinal origin may survive for sufficient time to be ingested by humans and livestock drinking the extracted groundwater. Studies have shown that some residues increased as pasture height decreased, indicating soil ingestion as the major means of pesticide intake by grazing animals. Herbicides applied to control weeds in irrigated pasture lands have the potential to contaminate groundwater.
Contamination at cattle and sheep dip sites is very high and potential exists for migration of contaminants to the groundwater. Organochlorine pesticide residues are still present in soils and continue to impact environmental quality several years after the discontinuation of their use. Discharges from livestock industries using veterinary chemicals may contaminate both surface waters and groundwaters. Current impacts on the industry from some other contaminates are small but sources of contamination should be monitored. Protecting and preserving markets requires certainty that livestock products are free from residues that have been accumulated under previous management regimes.
The freeing-up of water markets and the transfer of water allocations as a result of National Water Reform Agenda policies has caused considerable structural adjustment pressures within the livestock industry. Jurisdictional and institutional issues influence the widely varying regulatory policies for water development and use by the industry. The allocation of environmental flows has resulted in a significant reduction in water availability in some areas; the industry is more likely to feel the impacts of environmental allocations in the Murray Basin.
The greatest fraction of water consumption by the livestock industry occurs in the irrigation regions; it is in these areas that water availability is more likely to impact on the industry. The availability of water for the livestock industry in the irrigation sector is complicated by other beneficial uses for the water. The COAG water reform agenda has many aspects that are important to the allocation of water within the livestock industry. Under the National Action Plan (for salinity and water quality), there will be a substantial increase in water trading that will entail structural adjustment and affect the industry. Integrated surface water - ground water management plans and effective water trading regimes will be developed in the Murray-Darling Basin. The water reform agenda will continue and its impact on the livestock industry will increase.
Wind erosion directly affects costs and productivity through soil depletion, impaired water availability and higher costs of production. It can have impacts on public health and increase public reactions to wind erosion that may lead to controls on land use. Wind erosion removes particles that may be rich in nutrients and organic matter. Very high losses occur in extreme events. Wind erosion is influenced by climate, characteristics of the soil and land surface, and by land management practices. While the incidence of dust storms is lessening, high risk remains. The risk of wind erosion can be minimised by good management practices.
Maintaining vegetation cover is critically important. Vegetation cover increases surface roughness and reduces erodibility. Managing the cover of annual vegetation is especially critical to protecting soil from wind. Organic matter in the soil also reduces susceptibility to wind erosion. Pasture and tree management are the critical elements in any strategy for reducing erosion risk. Sustainable grazing systems should have maintenance of suitable vegetation cover as a major aim, but vegetation management needs to be linked to better information on climate. Better information is needed for vegetation management strategies tailored to specific regions.
Water erosion takes several forms. Sheet and rill erosion varies according to rainfall erosivity, vegetative cover, soil conditions and management practices. Water erosion removes fertile fractions of the soil resource and erosion generally exceeds the rate of soil formation across Australia.
The energy of rainfall (erosivity) is a key determinant of soil loss. The erodibility of soil is influenced by land management practices. Vegetation management to increase surface protection and roughness is a key to reducing soil loss. Pasture and tree management and ground cover maintenance are critically important because bare surfaces are extremely vulnerable to erosion. Protection of riparian zones is important and more information is needed to guide land management.
Impacts of water erosion on water quality are well understood and other environmental impacts are widely recognised. At the property level, erosion lowers soil and pasture productivity, increases input costs, damages farm water supplies and increases the risk of other problems. Water erosion affects productivity and can raise consumer and other public concerns. Issues include damage to infrastructure, increased costs for protection and maintenance, poor water quality, reduced biodiversity and inferior quality of products. The development and adoption of best management practices to mini mise water erosion is critical to sustainability of the industry and will ensure that community attitudes remain favourable. Land use needs to be matched to slope, soil type and the rainfall regime. Responses to water erosion may include increased regulation of the industry.
A high proportion of Australia's plants has developed in isolation and is vulnerable to introduced and invasive species. The rate of invasion varies, but is usually initiated by a disturbance to the native vegetation. The course of invasions is hard to predict and more research is needed. Single species invasions are characteristic of northern Australia; multiple species of the south. Rangelands are susceptible to weed problems, including native species that are considered to be weeds. Several types of weed are now serious problems in high rainfall areas of the coasts and uplands and can have serious impacts on the industry.
Weed research has been concentrated on agriculture, horticulture and forestry. Other than biodiversity, the effects of weeds on ecosystems are poorly understood. Of about 30,000 exotic species in Australia, only a few have become serious weeds. The rate of spread of weeds depends on a combination of factors; these are well understood for only a few weeds.
Weeds have widespread effects on the productivity of agricultural and pastoral systems. Annual losses due to weeds have been estimated at $3.3 billion; a substantial component accruing to the livestock industries. Many weeds are the first 'colonisers' of disturbed environments and they can exclude grazing over large areas.
Fire and grazing can combine to ameliorate or, equally, to exacerbate weed problems and good burning strategies are needed in pasture management. Research and data collection is needed to improve understanding of the long-term effects of fire as a management tool. Working with nature is more likely to be a successful weed control strategy and yield better results than will be provided by attempts to eradicate weeds.
Some industry practices contribute to weed invasions and pastoralist, conservationist and community interests could become polarised.
The livestock industry must recognise community views that include a perception that the industry is the cause of many environmental problems. Community and export market concerns could increase pressure for direct government involvement and control by regulation. Response strategies for the industry will need to be based on assessments of the balance between risk of environmental damage and the potential loss of productivity from changing management practices. The key will be to find a balanced path between changes in environmental conditions and the industry's own inevitable impacts on the environment. Enlightened management can counter many unfavourable perceptions of the livestock industry.
MLA may need to address a significant requirement for social science research and improved public information resources. MLA needs to be able to establish and argue that the industry is addressing environmental goals. The industry will need to improve its capacity to respond rapidly and effectively to public pressure. MLA should focus on "hooking into" current research initiatives in order to maximise their relevance and value to the industry.
This page was last updated on 10/11/2014
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