his chapter focuses on identifying ways of minimising the impact of farming on surface water, ground water and land resources.
Many of the strategies suggest the need to develop best management practise techniques for various aspects of farming. To develop these guidelines there will need to be an ongoing commitment from farmers and research organisations. Farmers have the principal responsibility for these issues.
Please Note: It is important to recognise that the strategies identified in this chapter will need to be built on as new knowledge is developed and targets are achieved. At this stage they provide a starting point and a framework for commitment from all the parties involved in Land and Water Management on the Ord.
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Reduce ground water levels to below two metres from the surface across the whole irrigation area within five years while preventing any new areas from rising above that level.
- Hold the quality of ground water at or above the high quality present in 2000.
Background
Prior to the development of irrigated agriculture the ground water levels would have fluctuated with the wet and dry seasons. As occurs in all irrigation developments where ground water is not used for irrigation, irrigated agriculture has resulted in rising ground water levels.
There is a network of monitoring bores (piezometers) located throughout the ORIA. Some of these bores have been in place and monitored since 1964, and an additional network of 60 on farm bores has been installed since 1991. This has enabled long-term trends to be established and the influence of on farm management techniques on the rate of rise of the ground water to be measured.
There are several factors that have contributed to ground water recharge and therefore caused the levels to rise. During the early years of irrigation leakage from the infrastructure (channels and drains) contributed a large portion of the recharge. As the water mounds under the leaky channel and drains approached the surface reducing the pressure gradients this source of accession declined in importance. As more areas were brought under irrigation the principal source of recharge into the ground water system has become leakage from on farm irrigation infrastructure and through irrigation fields (Water Corporation, 1997).
The preparation of hazard maps based on long term monitoring of ground water levels prompted farmers to consider the development of this Land and Water Management Plan. Rising ground water has been shown to pose a significant risk to the long-term viability of the ORIA through the related risks of salinisation and waterlogging.
If ground water levels are not managed and the ground water is allowed to rise close to the surface it is likely to cause waterlogging in the short term and soil salinity in the long term.
Current estimates indicate that about 75% of dry season ground water accessions are directly related to on farm irrigation, leaving 25% of the accessions coming from leaking supply and drainage infrastructure.
Wet season rainfall can also have a significant influence on the ground water levels in the irrigation area. Prior to irrigation the dry season would have acted as the “dry down” period for the ground water, however, now that irrigation occurs throughout this “dry down period” there is no opportunity for the levels to drop.
The general rate of rise of the ground water is between 10 – 80 cm per year across most of the valley. To date there are three areas where the ground water is within two metres of the surface. Risk mapping has been completed for the ground water levels across the valley (Water and Rivers Commission, 1996). This mapping highlights areas that may be at risk in the future. There are also contour maps of the ground water levels (Water and Rivers Commission, 1996).
Management Options AvailableThere has been a substantial amount of work completed on ways of controlling the rate of rise of ground water levels – both locally and in other irrigation areas around the world. Varying amounts of information are available on management approaches to rising ground water.
Known to work locally: -De-watering: Pumping ground water and reusing it for irrigation can only occur where there are porous gravel beds (aquifers) to transmit water laterally, the water quality is generally satisfactory for reuse, and the bore yield is sufficient to justify the capital and operating costs of pumping. Such gravel beds underlie approximately two thirds of the valley and they contain reasonable quality water thus enabling pumping to be considered in these areas.
Pumping has been tested in two locations and has been shown to keep the ground water levels at a manageable level. The report done on this pump testing (O’Boy, 1998) indicated that in the short term there would need to be two additional production bores in place on the Ivanhoe Plain, and one additional bore on the Packsaddle Plain.
According to a report done by Sinclair Knight Merz for the Water Corporation in 1998, this is the best available option to control rising ground water and would be more efficient when combined with other management options such as lining the M1 Channel.
Irrigation Management: The amount of irrigation water entering the ground water can be minimised by managing irrigation water to supply the optimum amount of water to the plant while minimising the amount of water running off or infiltrating to deeper levels (seeSection - Irrigation Management ).
Known to work elsewhere – not locally tested:-Permeability mapping: This tool enables the permeability of the soil to be determined therefore identifying and improving management of “leaky” areas. This is used in rice growing areas elsewhere in Australia to define where rice can and can’t be grown.
Deep Drainage: This involves using tile or mole drains. This method is used in other areas around the world, however it is a less desirable option as it relies on waiting for the ground water levels to be high (less than 1.5 metres from surface) before it can be applied.
According to the Sinclair Knight Merz report (1998) this method is likely to be effective, however it is expensive and is unlikely to be adopted by local farmers.
Tree Planting: Trees are used in other farming areas around Australia to help control localised areas with high ground water levels.
Known to work elsewhere – with some local knowledge:-
Irrigation Management: There are also techniques that are used elsewhere but have not yet been extensively tested locally, including trickle irrigation, soaker lines, lateral move and centre pivot sprinkler systems (see Section – Irrigation Management).
Currently flocculants are being used to aid in reducing soil, chemical and nutrient losses off farm through tail water.
Flocculants have properties that encourage fine clay particles to adhere to each other keeping air spaces open, thus increasing lateral infiltration. By increasing the rate of infiltration and therefore reducing the volume of water applied (the time taken to sub up each seed bed would be less)the amount of water moving into the ground water may be reduced.
Projects under way- Permeability mapping trial aimed at testing the use of the EM31 technology under local conditions.
- Irrigation management work (Refer to Irrigation Management).
- Monitoring of ground water levels and salinity.
- The ability of flocculants to reduce ground water accessions.
- The use of deep drainage locally.
- The use of trees under local conditions.
Reduce the rate of entry of water into the ground water by:
1. Improved irrigation management that is based on:
a) Better matching the field run length, irrigation water head, slope and siphon size to ensure the most efficient application of water within the constraints of a surface flow system and crop requirements.
b) Using irrigation systems (such as trickle and sprinkler) that give greater control over irrigation efficiency where they can be justified.
c) Using flocculants to improve the rate of water subbing thus reducing irrigation time necessary to fill the soil profile.
2. Reduced leakage of water by:
Strategy 2a) Identifying areas of irrigation bays that leak and adjusting irrigation and cropping management to reduce or eliminate leakage from these areas. This could mean removing these areas from irrigation or planting different crops (such as tree crops) in these areas.
b) Identifying, sealing, and /or lining leaky parts of the channel and drainage infrastructure.
c) Developing new management systems at the time of initial irrigation (following the wet season), such as controlling soil “cracking” and therefore reducing recharge at this time.
d) Reducing wet season recharge by using cover crops planted at the end of the dry season.
e) Planting high water use trees on land near leaky infrastructure and strategically throughout the valley.
f) Surveying irrigation fields and where appropriate installing interception sub-surface drainage systems below cropping areas.
Remove ground water and either reuse or remove it by:
1. Installing and operating a system of de-watering bores that enables:
a) Water of satisfactory quality to be reused for irrigation.
b) Poorer quality water to be released safely to drainage points.
2. Planting high water use trees strategically throughout the valley.
Strategy 3Monitor management impacts and research improved management methods by:
1. Continuing to monitor ground water levels across the irrigation area.
2. Encouraging farmers and research organisations to continue to gather information from bores and excavations to better identify the nature and extent of suitable aquifers for de-watering.
3. Investigating the usefulness of Electromagnetic (EM) technology to identify areas of “leakage” and therefore likely problem areas.
4. Identifying areas that may be suitable for low volume pumping and testing this approach to managing accessions.
5. Developing whole management systems based on best current available knowledge and testing these systems on farm.
Most of the necessary changes to irrigation management will involve farmers committing to on farm modifications to infrastructure and management systems that will affect farm operating costs.
Research into new systems and testing existing but locally untried solutions will be a responsibility shared between farmers and Department of Agriculture. The establishment and operation of production bores should be a shared responsibility between the farmers and Water Corporation as the main contributors to the rising ground water problem. The operation and servicing of the network of bores could be a negotiated responsibility for the Ord Irrigation Cooperative who should also be involved, with Department of Agriculture (who are taking the lead role), in surveying the permeability of soils throughout the irrigation area.
Ongoing monitoring of regional ground water levels should remain the responsibility of the Water and Rivers Commission with Department of Agriculture involved in on farm monitoring. Farmers will need to be involved in the collection and application of information generated from the monitoring systems.
Current Status - Ground water QualityThe Water and Rivers Commission has monitored the salinity in the ground water throughout the irrigation area since 1964. From this monitoring a contour map of these levels is produced (Water and Rivers Commission, 1996).
Generally, the salinity levels (electrical conductivity) in the ground water are low (500 – 1000uS/cm) and changing at very low rates. There are, however, some isolated areas where the salinity levels in the water are too high to reuse the water for irrigation (3000uS/cm). Most of the ground water across the valley has an electrical conductivity of between 500 – 2000uS/cm. This water is suitable for reuse for irrigation, by either shandying with supply water or using directly.
While the ground water is kept more than 1.5 metres from the surface the potential for sodicity problems (high sodium levels) and salinisation problems is very low. However, if this water approaches the surface then these problems are likely to occur (Water and Rivers Commission, 1997-98).
During a test pumping trial in 1997-98 the water quality at two sites was tested more thoroughly. The electrical conductivity at the Packsaddle bore location was approximately 1100uS/cm (no impact on plant growth), and the water at the Ivanhoe bore location was 2300uS/cm (which needs to be mixed with irrigation water before use on crops). There were no traces of pesticides or chemicals at either of the two sites tested.
Strategies – Ground water QualityWhile salinity is the greatest risk to ground water quality, controlling rising levels of ground water will have the effect of reducing the risk of damage from this source. It is necessary to pay greater attention to the risk of ground water contamination, as it will have serious consequences for future use of the underground water resource as well as potential environmental damage. There are significant potential risks to human health should drinking water supplies become contaminated.
Strategy 1Minimise the risk of contaminating ground water by:
1. Better understanding issues associated with the quality of ground water and the risks of contamination posed by nutrients, salinity, agricultural chemicals and harmful bacteria.
2. Develop management systems that reduce the risk of mobile nutrients such as nitrates, sulphates and heavy metals from reaching the ground water.
3. Conducting education programs to create an awareness of the potential problem and ways of reducing the risks
Strategy 2Provide useful information on the levels of contamination by:
1. Monitoring ground water quality throughout the irrigation area with the necessary frequency and spatial distribution of sample points. This monitoring requires a long-term commitment from funding agencies.
2. Encouraging farmers who use ground water on farm to include quality tests of this water as part of quality assurance programs.
Responsibilities – Ground water QualityOrd Irrigation Cooperative, Water and Rivers Commission and Department of Agriculture should be involved in monitoring the quality of ground water throughout the irrigation area. Farmers should be responsible for introducing management methods to minimise the risks of contamination and they should be encouraged to adopt regular monitoring as part of quality assurance programs.
ReferencesC.A. O’Boy (1998), Ord River Irrigation Area Long-Term Test Pumping, Hydrogeology Report No. 125/1998, Water and Rivers Commission.
C. Yesertener (1997), Review of Ground water Monitoring Data in the Ord River Irrigation Area, Hydrogeology Report HR60, Water and Rivers Commission.
Sinclair Knight Merz (1998), Ord River Irrigation Area Stage 1 – Control of Rising Ground water Level, Water Corporation Western Australia.
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To improve irrigation management to achieve 65% average annual water use efficiency on all irrigation farms within 5 years.
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To improve irrigation infrastructure and management to achieve a water delivery efficiency of 75% within five years
Irrigation is used to provide an appropriate soil moisture environment for optimising crop production. It is essential that adequate water is supplied for crop growth and that it is provided in a way that does not adversely affect growth, for example, through waterlogging. It is also important that water is applied in a way that does not adversely impact on the on farm or off farm environment and compromise sustainability of the farming system.
Irrigation requirements vary from crop to crop and aim to replace evaporation or part thereof depending on the crop water use characteristics. On the Ord, the average evaporation is more than 3000 mm and the average rainfall close to 760 mm. The very high evaporative demand has implications for crop water requirements as well as the design of water storages.
In developing best practice irrigation management it is therefore important to consider how to apply irrigation water, how frequently to apply it (scheduling) and how much to apply at each irrigation. Optimising these factors will lead to improved water use efficiency and help ensure the viability and sustainability of irrigated agriculture.
The predominant soil types used for irrigated agriculture in the Ord are the clay soils (Cununurra clays and Aquitaines). Smaller areas of levee type soils (Ord loamy sand and Ord sandy loam), sandy soils (Cockatoo sand) and Packsaddle red soil are also irrigated. Characteristics vary greatly between these soils, influencing irrigation management requirements.
The majority of broad-acre and some horticultural crops are grown on the clay soils. These include sugar cane, cucurbits, hybrid seed, chickpeas, maize, cotton and mangoes. Water requirements and irrigation management practices vary between these crops although most are watered by furrow irrigation from head ditches with only small areas of trickle irrigation used. The levee type soils and sandy soils are used mainly for tree crops (bananas, mangoes, pawpaw and other tropical tree fruits) and annual horticultural crop production (cucurbits, onions, tomatoes and other small crops) using either under tree micro sprinklers or trickle irrigation.
While earlier work on irrigation emphasised improvement in crop productivity through development of irrigation schedules, more recent research has also emphasised the need to consider application methods to improve water application efficiency to minimise tail water losses and deep infiltration into the ground water system.
Current StatusStrategies to improve irrigation practices for individual crops have been investigated throughout the life of the Ord River Irrigation Area. There has been an increasing awareness about problems associated with accessions to the ground water and recent research has been oriented towards optimising water to the crop while minimising the risk to the ground water. Adoption of the research results has not been universal, however many growers are moving towards more efficient irrigation practices.
Irrigation SchedulingScheduling of irrigation refers to the timing of intervals between irrigations. Scheduling information has been developed for a range of crops grown in the Ord including maize, chickpeas, bananas and mangoes. For maize, it has been found that the highest yields are obtained with frequent and rapid irrigation. Rapid irrigation is also now generally used for furrow irrigation of other crops on clay soils in the Ord to minimise waterlogging effects. While this practice can result in minimal drainage below the root zone and can result in acceptable levels of less than 30% of applied water ending up as tail water at each irrigation, scheduling irrigation at high frequency can also result in more tail water flow over the whole season. This is due to the increased number of irrigations required.
Where research hasn’t been undertaken locally for all crops, there is usually adequate crop water requirement information available from elsewhere which can be adapted to local conditions.
Efficiency of ApplicationIn addition to establishing the correct timing of intervals between irrigation, it is also necessary to determine how much water to apply and this can significantly effect efficiency of application. With furrow irrigation on clay soils, improving efficiency will depend largely on minimising both tail water run-off and deep drainage below the root zone into the ground water system.
Variation in application efficiency will result from a range of factors including soil structure, soil moisture characteristics, irrigation bay characteristics and irrigation management practices.
Tail water flows in the ORIA vary between 30 and 70 percent of irrigation water applied. Management practices which will reduce the quantity of tail water are currently being examined (Section Surface Water Quality Management Strategies).
Inefficient application of irrigation water on farm is contributing approximately 75 percent of ground water accessions, through deep infiltration. It is also known that there is significant variation across the Irrigation Area in permeability of the soils with high rates of infiltration in some areas and insignificant rates in others.
Some of the areas with higher rates of infiltration have been broadly identified through observation of rapid changes in levels in ground water monitoring bores during irrigation. Other areas have been identified through observation of changes in soil moisture below the root zone during and following irrigation.
Higher infiltration rates can occur where lighter textured soils intercept surface clays and create preferred pathways for water movement. Further work will be required to adequately identify these areas to allow alternative management practices to be used in areas where deep drainage is resulting in rising ground water. Permeability mapping is planned to provide this information.
Projects under wayA current research project will examine optimum irrigation requirements for sugar cane. This work is examining crop response to irrigation frequency as well as ways of minimising both tail water flow and deep infiltration below the crop root zone. Economic analysis will be undertaken to determine optimum irrigation management practice for the sugar cane crop considering both production and environmental requirements. Much of this information will be adapted for use with other crops grown in the Ord.
Irrigation practices currently used for cotton production in the ORIA are based on techniques developed for the NSW industry. Research is in progress to adapt this information to improve management in the ORIA. Both frequency and duration of irrigation are being examined.
Further work will be required to ensure that irrigation practices developed are also compatible with requirements for ground water and tail water management.
Knowledge RequiredPermeability mapping to identify localised areas where soil infiltration rates are high is required. This would allow alternate irrigation practices to be used in appropriate areas, a reduction in potential accessions to the ground water system and better management of ground water through an increased understanding of how water is moving both vertically and laterally. There is a proposal currently being developed to undertake this work in the Ord using existing Electromagnetic technology developed for similar use in irrigation areas in eastern Australia.
Economic analysis to determine optimum irrigation practices for crops grown in the Ord, taking into account crop water requirements, efficiency of application and ground water management. Much of the previous work undertaken and practices adopted have largely considered crop water requirements.
New techniques for improving infiltration within the crop root zone would potentially allow more rapid irrigation while also reducing the frequency of irrigation and hence reduce tail water flows. Some growers are using Polyacrylamides for this purpose and their use could be investigated further.
StrategiesStrategies designed to reduce the environmental impacts of irrigation and improve water use efficiency need to be developed within the context of the existing irrigation infrastructure. The system was designed to allow large volumes of water to flow through, thus creating a self-flushing effect during the irrigation season and enabling wet season run-off to move quickly away from cropped areas.
Irrigation management strategies are aimed at reducing environmental pressures and in so doing will have the effect of improving water use efficiency.
Strategy 1Improve water use efficiency and reduce surface water losses by:
1. Investigating, demonstrating and adopting alternative irrigation systems for cracking clay soils including trickle, sprinkler and soaker technologies where clear environmental and economic benefits can be demonstrated.
2. Identifying suitable locations for demonstrating the effectiveness of tail water reuse and recycling systems.
3. Developing and testing tail water recycling systems that might be suitable for the Ord River Irrigation Area so that in the medium to long term tail water can be safely and cost effectively recycled.
4. Researching and disseminating information on optimal field layout, run length, grade, siphon size, irrigation time, bed and furrow size and shape based on a better knowledge of the needs of different soil types.
5. Ensuring irrigation fields are leveled to appropriate uniform grades and that the guides from 4. above are adopted.
Strategy 2Improve water use efficiency and reduce ground water recharge by:
1. Identifying areas of soils that leak by researching the usefulness of Electromagnetic technology to map soil permeability under local conditions.
2. Developing irrigation and drainage systems to manage soils of high permeability.
3. Identifying and adopting management practices that minimise accessions to ground water during pre irrigation and initial crop irrigation. Of particular interest will be the investigation and development of methods of using Polyacrylamides (PAM) to increase the rate of water subbing across beds following crop planting.
4. Ensuring that any on farm water storage associated with tail water reuse is correctly sealed to prevent accessions to the ground water.
Strategy 3Provide research, demonstration and monitoring services to:
1. Quantify the level of accessions to ground water and measure trends in ground water levels.
2. Quantify the volume of water leaving farms as irrigation tail water.
3. Investigate and demonstrate new irrigation management techniques with particular attention being placed on cost effective improvements in water use efficiency.
4. Map soil permeability for problem areas of the Ord River Irrigation Area.
5. Develop guides for irrigation field layout and bed and furrow configuration for optimal water use efficiency.
ResponsibilitiesBy far the largest commitment in terms of direct costs associated with implementing these strategies will need to be made by the farming community. Most of these costs will be associated with implementing improved management such as laser levelling, field layout, farming inputs, machinery modification and changed practices. To balance this it is likely that they will also be the beneficiaries of the improved management through reduced water costs and improved crop performance.
There will be a requirement for commitment to support long term monitoring and research from a number of state government agencies including Department of Agriculture, Water and Rivers Commission and W. Specific approaches to R&D Corporations may be necessary to develop the management guides, monitoring methods and management practices.
Goals
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To improve irrigation management to achieve 65% average annual water use efficiency on all irrigation farms within 5 years.
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To reduce the load of chemical contamination in tail water by 40% within 5 years.
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To reduce the load of nutrient contamination in tail water by 40% within 5 years.
Surface water quality is adversely affected by the presence of sediment, and the nutrients and chemicals carried by the sediment and dissolved in the water. There are few past records of water quality for the Ord River and surrounding waterways. Where they are available they generally relate to specific projects and therefore long term trends in water quality are not available for the area.
ChemicalsThe general community sees chemicals that are entering the river via surface water as being a critical issue. In April 1998 the Water and Rivers Commission and the Ord Irrigation Co-operative undertook to design a program to monitor water quality throughout the irrigation area, the Ord River and some tributaries. Samples are collected monthly and sent to Perth for complete analysis of organophosphates, organochlorines, nutrients, salinity and turbidity levels. Throughout 1998 and 1999 the program was refined and rationalised to a total of 32 sample sites.
Since the sampling program began, the main pesticide detected has been Endosulfan. The insect pest pressure was extremely high during the 1998 growing season and there was a corresponding high number of “shows” of the chemical throughout 1998. Pest pressures during 1999 were lower and there were fewer “shows” of chemical, however there were high levels of Endosulfan recorded at three locations around the irrigation area during 1999. There have also been a limited number of shows of other chemicals in the water that cannot be easily explained.
It should be noted that Endosulfan is toxic to aquatic species and therefore it is the focus chemical for the water sampling program. Endosulfan is a useful and important chemical as it is “friendly” to non-target organisms (except fish) and is important for pest control as it is in a different chemical group to other insecticides available (therefore it is important for managing insect resistance to chemicals).
NutrientsNutrient enriched tail water has the potential to severely degrade the river system however the impacts are less dramatic than fish kills and symptoms may take years to become obvious. In some cases impacts are only seen during unusual events such as the algal blooms on the Swan River following heavy summer rains in January 2000. With the reduced river flows possible following the development of Ord Stage 2 the risk of elevated nutrient levels in the river could increase.
SedimentIncreased sediment levels from farm run-off during the wet season would be difficult to detect due to the large sediment loads carried by the rivers at that time. However, the cost of maintaining drainage infrastructure and of the loss of topsoil from farms makes sediment reduction an important economic consideration for farmers. A significant proportion of nutrient and chemical movement off farm is on the small colloid particles within the sediments so reducing both large particle sediment and retaining the colloid fraction on farm is necessary if the river system is to be protected.
Current Status Tail waterRiver: Under current flow conditions the threat that tail water poses to the health of the river is low to medium. The river flows for 12 months of the year and the amount of flow in the river is much greater than the flow from drains therefore leading to high dilution factors. The impacts of reduced river flows that may follow changes in water allocation is unknown.
There are other factors that may be having an impact on the water quality in the river, such as rubbish, (see Section – Recreational River Use) and stock access causing erosion (see Section - Fuel Storage on Farm).
Projects Under way-
The study “Productivity and water flow regulation in the Ord River of north Western Australia” is now under way. The Water and Rivers Commission and two Perth universities are involved in the project, which should be completed by 2002 (pers comm Paula Deegan, Water and Rivers Commission, Sept 1999).
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There is currently a proposal for a project called “Resilience of the Ord River to Irrigation Return”. This project has not yet been finalised.
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The levels of pesticides, sediments and nutrients the river can handle before there are negative impacts on the system.
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The amount of tail water that is leaving the area.
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The extent and nature of soil loss from irrigation farms throughout the cropping cycle and during the wet season.
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The actual impact of recreational use on the water quality in the river.
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The LC 50s for the native fish species for the pesticides used in the area?
The three main issues with surface water quality are the sediment, nutrients and chemicals that enter these surface waters. Many of the strategies that will reduce sediment loading in the tail water will also have beneficial effects by reducing the export of nutrient and chemical from farms to the drainage and river systems.
Ultimately, a range of these improved management practices needs to be incorporated into a best management practice framework that can be updated as the benefits and costs of various strategies are identified.
General surface water quality management strategies
Strategy 1Improve irrigation management by reducing sediment loads in tail water by:
1. Ensuring that all irrigation fields are levelled to a grade that minimises the risk of soil movement. Tail drain and farm drainage outlets need to be constructed to minimise the risk of erosion.
2. Designing irrigation fields with run length, grade, siphon size and watering interval such that fields can be fully watered in the shortest practical time.
3. Employing erosion stops and sediment traps on farm and drop-structures where tail water has to drop significant heights.
Strategy 2Reduce the volume of tail water by:
1. Investigating the potential for alternative irrigation techniques and their likely impacts on soil loss and increasing adoption where possible.
2. Identifying suitable locations for demonstrating the effectiveness of tail water reuse and recycling systems
3. Developing and testing tail water recycling systems that might be suitable for the ORIA so that in the medium to long term tail water can be safely and cost effectively recycled.
Strategy 3Use farming practices designed to reduce erosion during both the cropping and wet seasons by:
1. Growing cover crops to reduce erosion during the high intensity rainfall events leading up to the wet season.
2. Using Polyacrylamide (PAM) to improve irrigation efficiency and retain sediment (including colloids) infield.
3. Investigating and developing farming systems that employ forms of mulching, surface modification and other practices that are designed to reduce soil loss.
4. Reducing the number of unnecessary cultivation passes and using minimum tillage practices where possible.
Strategy 4Employing off farm management options by:
1. Demonstrating and installing artificial wetlands where possible within the drainage system to filter tail water.
2. Revegetating areas of steep slopes and high erosion risk particularly in areas adjacent to drains and the river.
Management strategies for reducing nutrient loss Strategy 5Minimise the risk of fertiliser movement off farm by:
1. Accurate placement of fertiliser within the plant root zone (bury fertiliser).
2. On permeable soils applying small amounts of fertiliser matched to crop growth demands through sprinklers and drip irrigation systems
3. Using foliar fertiliser to meet crop demands
4. Applying PAM to irrigations following fertiliser placement particularly when fertilisers are spread rather than placed within the root zone.
Strategy 6Prevent fertiliser from reaching the river system by:
1. The construction and management of artificial wetlands on the major drains within the ORIA.
2. Encourage the development and use of less mobile forms of fertilisers and nutrients (eg Nitrogen from cover crops)
Management strategies for reducing chemical export Strategy 7Reduce the risk of chemical movement off farm by:
1. Developing and implementing codes of practice for the application of pesticides through certification and audit of commercial and farm spray operators.
2. Implementing application methods based on accurate placement of pesticides.
3. Using less volatile formulations of pesticides.
Strategy 8Reduce the amount of chemical used by:
1. Ensuring spray operators and farmers have all the up to date information on correct application rates.
2. Implementing well managed Integrated Pest Management programs for all crops based on :- Chemical usage being matched to a spray calendar and based on monitoring pest pressure A range of cultural, chemical and natural management strategies.
3. Utilising modern gene technology so that crops rely less on chemical control of pests.
4. Developing farming systems that maximise the natural plant defences against pest and disease attack.
Strategy 9Reduce the environmental risk posed by pesticide use by:
1. Ensuring the registration and use of environmentally soft products with short half lives such as: Products based on natural pathogens such as bacteria and viruses, Pheromones and other products that interfere with breeding cycles.
Strategy 10Provide research, demonstration, monitoring and training services to:
1. Monitor soil loss from farms and sediment, nutrient and chemical loads of drains and river systems at intervals throughout the year.
2. Quantify the soil, nutrient and chemical composition of sediment mobilised in tail water, and trapped in silt traps.
3. Monitor tail water flow volume.
4. Provide research facilities and resources to investigate new management initiatives and to demonstrate systems for managing sediment movement.
5. Encourage the use of crop scouting services to monitor pest populations and enable appropriate pest control methods to be applied.
6. Ensure registration of appropriate chemicals for crops being grown in the irrigation area.
7. Encourage the continued development and availability of new improved chemicals.
8. Provide training in chemical use, farming methods and nutrition management in crops on the Ord.
ResponsibilitiesBy far the largest commitment in terms of direct costs associated with implementing these strategies will need to be made by the farming community, as most will be costs of implementing improved management such as laser levelling, silt traps, and general farming practices. To balance this it is likely that they will also be the biggest beneficiaries of the improved management through reduced soil and nutrient loss.
There will be a requirement for commitment to support long term monitoring and research from a number of State Government Agencies including Department of Agriculture, Water and Rivers Commission, Water Corporation and Conservation and Land Management. Specific approaches to R&D Corporations may be necessary to develop the research and monitoring methods and framework. Chemical companies and the National Registration Authority need to be focussed on providing a suite of more environmentally friendly chemicals for tropical cropping areas like the Ord.
Community support for the strategies through voluntary programs of monitoring and information gathering will likely involve groups such as river using tour operators, recreational fishing groups and the Ribbons of Blue program.
ReferencesThe Water and Rivers Commission, Kununurra office, provided the water quality data.
Australian & New Zealand Environment & Conservation Council, (1992) Australian Water Quality Guidelines for Fresh and Marine Waters
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A 100% increase in the adoption of Integrated Pest Management for all compatible crops within five years.
The wise use of chemicals is critical to sustainability of agriculture and is a component of best management practice in modern agriculture. There are a number of issues relating to the sustainable use of chemicals that need to be considered including the management of resistance in pest species, the development of integrated pest management systems and aerial spraying operations.
Resistance ManagementProlonged exposure to a particular chemical will lead, through selection pressure, to the development of resistance to that chemical. This resistance will continue to build up until the chemical becomes less effective. Resistance to one chemical in a particular group may transfer resistance to other similar chemicals. The biology of insects is such that eventually they will develop resistance to repeatedly applied chemicals.
There is an ongoing resistance management strategy for Helicoverpa species in the ORIA. This is developed at the beginning of each season by Agriculture WA and the farmers. 1999 also saw the introduction of a resistance management strategy for melon aphids in the area.
Helicoverpa species: There are two species of Helicoverpa that are major pests to a wide range of crops in the ORIA. These species are called Helicoverpa armigera and H. punctigera. H. armigera has developed resistance to several groups of insecticides. This species does not migrate but remains in the area in low densities over the wet season, building up in numbers once new crops are established and usually becoming the dominant species by August. Since there is no inward migration of susceptible individuals resistance levels do not get substantially diluted from year to year. The other species H. punctigera, has not developed resistance to insecticides. While small numbers persist through the wet season these are supplemented by insects which migrate to the ORIA at the beginning of the season. These migrants usually come from areas where they have not been subject to insecticides and therefore have not built up resistance. This species is usually more abundant from March to July (Resistance Management Strategy for Helicoverpa spp in the Ord River Irrigation Area for 1999).
Melon Aphid: The melon aphid (Aphis gossypii) causes problems by transferring viruses in cucurbit crops. In 1997 resistance to pirimicarb and organophosphate chemicals was detected and in 1998 resistance to pirimicarb and organophosphates increased and moderate resistance to pyrethroids was detected for the first time. Endosulfan is the only registered chemical that aphids have not yet shown resistance to.
Resistance is hard to control in the melon aphid as the female produces live young without mating, hence interbreeding does not dilute the resistance levels. When aphid populations are low wingless females are produced and aphids will only move to touching plants. Winged females are only produced when the populations are dense and widespread dispersal and virus transmission will only occur at this stage (Resistance Management Strategy for Cucurbit Pests in the Ord River Irrigation Area for 1999).
Integrated Pest ManagementThe aim of integrated pest management (IPM) is to reduce the use of chemicals in pest management, and instead use a combination of control measures (biocontrol, cultural, genetic and chemical) that are less destructive to the environment (IPM, 1999).
All major agricultural industries are looking at developing IPM strategies to control their pests. One industry that has put a large amount of work into IPM is the Australian Cotton Industry.
Aerial Spraying OperationsThere are two aerial spray operators currently operating in the Ord River Irrigation Area. They spray a range of crops throughout the irrigation area.
There is an Aerial Agricultural Association of Australia (AAAA) which consists of operators of agricultural aircraft. Currently this organisation has 75% of the aerial operators around Australia as members. Accreditation is an involved process and operators must:
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Demonstrate their interest in improving and sustaining their professionalism.
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Employ only industry approved, examined and trained personnel in agricultural operations.
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Comply with agricultural, health and environmental legislation.
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Abide by manufacturers’ and approved recommendations regarding applications of agricultural chemicals.
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Have spraying and spreading aircraft fitted with positive shut-off equipment.
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Have spraying aircraft fitted with a smoker for drift detection and a flow metre for accurate spray application.
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Demonstrate competent house keeping in their mixing activities, loading equipment and chemical storage and handling facilities.
(More information can be found in the Pilots and Operators Manual {Woods & Lisle, 1998}).
The AAAA provides continual training for its members and up to date information on new products on the market etc.
Current KnowledgeCurrent pest control strategies for the ORIA have been developed over years of scientific study and practical application. The unfortunate legacy of the early cotton developments and consequent over reliance on chemical controls has created sensitivity among farmers to the use of chemicals. Some practices imported from other areas have not proved to be effective, however new approaches are continually being tried in an attempt to reduce the money spent on chemicals; as well as to reduce the environmental risks
Resistance ManagementAll farmers play an integral role in controlling resistance in pest species by having input into the resistance management strategy (in conjunction with Department of Agriculture), at the beginning of each season.
Helicoverpa species:The current resistance management strategy for the Helicoverpa species has the following components:-
a) Prevent build up of Helicoverpa populations with early suicide crops.
b) Use the calendar window approach – the season is divided into three windows in which different groups of insecticides are sprayed.
c) Targeting species – knowing which of the two species is present and tailoring the spray program to suit.
d) Minimise insecticide applications – eg. by using scouting techniques and setting pest population thresholds to determine when to spray.
e) Treat larvae when small.
f) Use only recommended chemical mixtures.
g) Eliminate insecticide resistant H. armigera at the end of the season – for example by using suicide crops.
Melon aphids: The current resistance management strategy for melon aphids includes:
a) Using the calendar window approach.
b) Scouting and trapping.
c) Sending samples away for resistance testing.
There were much lower levels of melon aphids during the 1999 season than during 1998. As a result mosaic virus levels in cucurbit crops were also low in 1999 (Cucurbit Pest Newsletter, No.4, 1999).
The 1999 season saw much lower melon aphid levels than the 1998 growing season (due to weather conditions etc). Corresponding to this low level, the virus levels in cucurbit crops were also low in 1999 (Cucurbit Pest Newsletter, No.4, 1999).
Integrated Pest Management (IPM)Cotton: All the cotton that is grown in the ORIA (~1000ha in 1999) is grown under an IPM system. This involves using suicide crops, companion crops, beneficial insects, soft chemicals, bug scouting techniques and genetically engineered cotton (Bt).
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Trap crops, such as Lucerne and lab-lab, act to attract (and “trap”) the pest insects and as refuge for the beneficial insects.
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Beneficial insects are those that are natural predators to the pest species.
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Bug scouting is done on every field twice a week and sprays are only applied when the numbers of pest species reach threshold levels.
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Soft chemicals generally do not kill the beneficial insects, and therefore, if insect numbers get over thresholds then there are chemicals that can control the pests without killing all the beneficials.
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There is no Endosulfan used on Bt cotton in the ORIA.
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Chemicals that are used in cotton include Pirimicarb, Amitraz and Gemstar (Amanda Annells, pers comm).
Other Crops: There are a number of other crops that are being grown in the valley utilising some aspects of the above system.
There are a number of melon growers who are adapting their management in line with some of the ideas of cotton IPM methods. Other growers are using bug checkers (eight growers employed the Ord River District Co-op to carry out bug checking for them during 1999) and threshold levels to determine when application of chemicals is required.
All of the chickpeas that are grown in the valley are scouted regularly for Helicoverpa. There was ~ 450 ha of chickpeas grown in the valley in 1999.
Aerial Spray OperationsIn the ORIA there is no requirement for spray operators to be accredited with the AAAA. One operator is accredited with the AAAA and the other operator is in the process of becoming accredited.
There are a number of issues associated with aerial application of chemicals as opposed to ground application. Aerial application:
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prevents soil compaction;
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is faster and ensures the farmer/operator is less exposed to chemicals than is the case with ground rigs;
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and an aerial operator can spray while the ground is still wet.
However, by using aerial application:
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there is increased likelihood of off target drift;
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more chemical is used (when plants are small ground rigs can “band spray” and spray the plant line only),
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evokes emotion/distrust by people who see the plane spraying.
There are limits to aerial spraying and there are jobs that need to be done by a ground based spray rig.
In Western Australia there are a number of Acts which relate to aerial spraying – The Health Act, 1974, the Occupational Health & Safety Act, 1984, The Aerial Spraying Control Act, 1966, The Environmental Protection Act 1986.
According to the Civil Aviation Papers Part 20 (CASAA), Air Service Operations – Aircraft engaged in Agricultural Operations, permission is granted to fly at a lower height than 500 feet over any area other than a city, town or populous area while the aircraft is engaged in:
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Agricultural operations authorised by an aerial work license issued under the Regulations; and
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Inspection flying related to such agricultural operations; and
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Transit flights to a treatment area up to a maximum radius of five nautical miles from the aerodrome or agricultural landing area when carrying an agricultural payload.
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The combination of IPM methods that would work best for cucurbit crops in the area.
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Are the threshold levels that are currently being used effective?
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What are the relationships between different crops in terms of IPM?
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Is there a need for a regional IPM strategy?
Reduce the risk of resistance build up in chemical control measures by:
1. Using all chemicals according to recommended rates and concentrations.
2. Developing and rigidly adhering to a well thought out spray calendar that is aimed at protecting individual chemical groups.
3. Using chemical control measures only when crop scouting indicates that spraying is necessary.
4. Using integrated pest management systems whenever possible and minimising the use of chemicals.
5. Developing an understanding of the patterns of resistance development to enable reliable prediction of likely problems.
Strategy 2Increase the adoption of Integrated Pest Management by:
1. Demonstrating the advantages of using a range of control measures including:
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Cultural methods,
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Soft Chemicals
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Predatory insects
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Trap Crops
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Crop Scouting
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Food Spray and other attractants
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Genetic modification
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Crop timing.
2. Further researching management methods so that satisfactory IPM systems can be implemented on a range of crops.
3. Establishing insect population thresholds to initiate sprays under tropical conditions.
Strategy 3Ensure optimal performance of all spray operators by:
1. Encouraging all operators to be properly accredited (aerial applicators AAAA, others Farm Safe).
2. Developing a responsible cooperative approach to flight paths to minimise the risk of accidental chemical contamination of the river system.
3. Encouraging the use of more sophisticated spray equipment that permits greater control over drift, chemical placement and amounts of chemical used.
Strategy 4Improve the image of spray operators and of aerial spraying as a control method by:
1. Ensuring good communication between neighbours to minimise the risk of conflict associated with spraying operations.
2. Increasing the amount of information on spraying and chemical use to increase community understanding about spraying.
3. Developing a code of practice and adhering to it.
ResponsibilitiesFarmers, spray operators and chemical suppliers need to work together to develop better systems. These new practices will involve certain levels of risk to farmers as control programs will be more sophisticated. There may well be cost savings through reduced chemical use. Plant breeders and seed producers will need to become more involved in looking for novel solutions through genetic modification.
Department of Agriculture, CSIRO and other research providers have a responsibility to help farmers to develop management systems that are less dependent upon chemicals. They should also be involved with ensuring adoption of the new practices, as they become available.
ReferencesCucurbit Pest Newsletter, No 4, September 1999, Agriculture WA.
Resistance Management Strategy for Helicoverpa spp in the Ord River Irrigation Area for 1999, Agriculture Western Australia.
Resistant Management Strategy for Cucurbit Pests in the ORIA FOR 1999, Department Agriculture Western Australia.
Integrated Pest Management (1999), www.waite.adelaide.edu.au
Brain Thistleton, Kimberley Regional Entomologist
Aircraft in Australian Agriculture, A Review, The Aerial Agricultural Association of Australia Limited 1998.
Woods, N., Lisle, R., (1988), Aerial Agricultural Association of Australia – Operation Spray Safe – Pilots and Operators Manual.
Goals
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100% of farmers to be accredited chemical applicators within two years
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100% of farm chemical stores to comply with Australian and Western Australian Standards within five years
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All past chemical container dump sites to be identified, assessed and, where necessary, contained within five years
All farming operations will to some degree be dependent upon the application of some chemicals. Agricultural chemicals may be harmful to humans and can affect all forms of life, so they need to be handled carefully and only used according to approved (registered) safe procedures. All chemical containers come with information on the correct use and handling of the chemical concerned.
The Farm Safe program provides for the compulsory training and accreditation of all users of agricultural chemicals. In some instances it will be an offence to sell chemicals to people without accreditation. This basic training is designed to provide the understanding necessary to use chemicals safely and for their registered purpose.
The Department of Minerals and Energy determines requirements for the storage and handling of agricultural chemicals. There is also an Australian Standard for the storage and handling of agricultural and veterinary chemicals (AS2507 – 1998). The large majority of farming operations in the valley would qualify for minor storage as they do not store large amounts of chemicals on their farms at any one time (and therefore these operations do not have to be licensed to store chemicals).
Current Guidelines for Storage(All information is taken from the Australian Standard for the storage and handling of agricultural and veterinary chemicals, and Department of Minerals and Energy Guidance Note – S319 REV 1 – Storage of dangerous goods on farming premises, Conditions for exemptions from licensing).
The guidelines for storage of these chemicals depends on the amount of chemical that is stored at any one time. The following is the maximum quantity of types of chemicals (PG= packaging group) that can be stored at any one time for the storage area to be classed as a “Minor Storage” area:
PG I - great danger (eg. Sodium Cyanide) - 1 (litre or kg)
PG II - medium danger (eg. petrol) - 250 (litres or kg)
PG III - minor danger (eg. kerosene) } - 1000 (litres or kg)
NDG – not classed as dangerous goods
Sprayseed (PG III), 2,4-D Ester (PG II), Roundup (NDG)
For more information on specific chemicals – see their Material Safety Data Sheets (MSDS).
Requirements for minor storage(These are guidelines only – not enforceable by law – and are designed to protect the handler of chemicals and the environment).
ConstructionSeparationa) The floor shall be impermeable to chemicals that are being stored.
b) Where there is the possibility of soil or water contamination there needs to be a method of containing leaks or spills in the storage area.
c) The area needs to be well ventilated and protected from heat and ignition sources.
d) Fire protection measures need to be provided in easy to access locations.
The minor storage area shall be separated by:
Segregationa) at least 15m from any unrelated work area, office, amenities or the boundary of the property;
b) at least 5m from any watercourse, body of water, drain or sewer not confined on the property.
c) If there are two or more minor storage areas on the farm then they can be treated as separate if they are 500m apart.
Segregation is the isolation of incompatible dangerous goods from each other. Incompatible dangerous goods need to be separated by at least 5m. Provision should be made so that any spillage of one product can not flow and come into contact with another incompatible product.
Example – Petrol/diesel/solvent based pesticides with AGRAN.
Secondary ContainmentSecondary containment is usually described as bunding, however it may simply be achieved by careful location of the dangerous goods on the premises.
The objective is to ensure that any spillage or release of dangerous goods is retained on the premises in a manageable area so that recovery can take place without injury to people, property or impact on the environment.
The natural contours of the ground sloping to an embankment, the use of compacted clay bund walls or deliberate sloping of the ground to a pit may also achieve this objective.
Outdoor Minor StorageQuantities
The following amounts can be stored outdoors:
PG I - 10 (litres or kg)
PG II - 500 (litres or kg)
PG III - 3500 (litres or kg)
Conditions
Storage areas for larger volumes of chemicals than considered minor storage.a) The size of the farm is at least 2 ha.
b) The area is kept clear of combustible vegetation for at least 3m.
c) Any potential spillage shall be prevented from reaching any protected place – using natural ground slope, kerb or bund.
d) Store is at least 10m away from any dwelling.
e) Separate from the property boundary by 15m.
There are more specific requirements for storage if the amount of chemicals being stored is more than the above mentioned amounts. These requirements include planning and design, location of the areas and construction requirements. Most farms would not store more chemicals than covered by minor storage categories. (Details are found in Section 3 of Australian Standard 2507-1998).
Strategies for Storage of Chemicals Strategy 1Ensure the safe handling and storage of chemicals by:
1. Creating greater awareness of the storage guidelines.
2. Encouraging farmer groups to promote safe chemical storage and handling on farm.
3. Ensuring that safe handling and wash down areas are included in quality assurance programs.
4. Locating spray rig filling and chemical mixing facilities away from channels and drains and ensuring that they are designed to safely contain spills.
5. Ensuring all chemical users are appropriately accredited under the Farm Safe Program.
Strategy 2Ensure the safe disposal of used chemical containers by:
1. Encouraging the Shire of Wyndham East Kimberley to become a participating shire in the Drum Muster Program to provide safe collection, temporary storage and disposal of used chemical containers.
2. Following 1.above, design and implement an information program to encourage farmers and other chemical users to participate in the Drum Muster Program.
Current Status - Historical Dumping SitesThere is an area behind Bethel Farm and an area on the Pacific Seeds – Cave Springs Farm. There are also lime lined disposal pits at the Research Station and at the old airstrip (this was the “best practise” at the time).
Knowledge Gaps-
The number of farmers who comply with the regulations.
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Other areas not listed above where chemical containers were dumped in the past.
Identify, contain and render safe past chemical container dumping sites by:
1. Identifying and clearly marking past disposal sites.
2. Characterising those sites to identify the current and future risks associated with them.
3. Take whatever measures are necessary to remove the risks to the environment or to human health associated with these sites.
ResponsibilitySafe management of chemicals within the environment and farming workplace will be dependent upon involving all farmers, other users, farmer groups and the community.
Department of Agriculture should be involved with farmer groups by ensuring the development and adoption of best practice and the provision of appropriate training and accreditation systems. The Department of Minerals and Energy and the Department of Environmental Protection have responsibility for working with farmers, suppliers, users and the community to ensure that storage and wash down facilities are safe. The Department of Environmental Protection and the community have responsibility for identifying and rendering safe, past chemical container dumping sites.
ReferencesGuidance Note S319 REV1, (1998) Storage of Dangerous Goods on Farming Premises, Conditions for Exemption from Licensing, Department of Minerals and Energy – Explosives and Dangerous Goods Division.
Australian Standard TM , The storage and handling of agricultural and veterinary chemicals, AS2507 – 1998, Standards Australia.
Goals
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100% of farm fuel storages to comply with Australian and Western Australian standards within five years.
There are requirements from the Department of Minerals and Energy and Standards Australia on the installation of storage tanks and the storage of fuel at any location (eg. on farm, service stations etc.).
Current GuidelinesThese guidelines refer to the storage of any flammable or combustible liquid and are sourced from Guidance Note S308, but will focus on the storage of diesel, as this is the most common fuel stored on farm in large quantities.
If the storage tank is 5000L or less (Minor Storage) then the requirements for storage and handling focus on safety issues. These are outlined in Section 2 of the Australian Standard for “The storage and handling of flammable and combustible liquids”.
When the storage tank is more than 5000L there are more requirements that need to be met. These focus on minimising the risk of fire and impact on the environment. These requirements are outlined in Section 3 of the Australian Standard for “The storage and handling of flammable and combustible liquids”(AS 1940-1993). These include requirements for tank construction, venting, underground tank installations, aboveground tank installations, dispenser requirements, fill point locations, tanker filling locations and fire protection.
Above Ground Tank InstallationAs the majority of on farm tanks are above the ground, the following is a summary of these guidelines.
a) Separation – the tank is required to be at least 15m away from office buildings, warehouses, workshops etc (if on the same property). The tank also needs to be not closer than 15m to the boundary. There are also requirements for separation from protected works on adjacent properties. If there are two storage areas on the property they must be at least 500m apart.
b) Bunding – a bund is required for any above ground tank in excess of Minor Storage as defined by Section 2 of AS 1940-1993. In general the bunding shall:
i. Contain 100% of the storage capacity of the largest tank.
ii. Be impervious to spillage and enable recovery of spillage.
iii. Be located not less than 1m from the tank
iv. Not be higher than 1.5m unless a means of rapid and safe entry and exit is provided and
v. Be able to withstand exposure to fire. (AS1940-1993)
c) Bunding can also be achieved by utilising the natural slope of the land with the use of compacted clay for bund walls (Guidance note S319).
Knowledge Gaps-
The best way to construct a bunding system for our conditions.
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The number of farmers who have storage areas that comply with the guidelines.
Ensure safe storage of fuel by:
1. Preparing and widely distributing clear easy to read guidelines to all farmers and other users of drum or bulk fuel.
2. Enforcing regulations and guidelines for fuel storage in bulk and drums.
Strategy 2Prevent surface movement of fuel and oil products by:
Developing and enforcing Shire by-laws that prohibit the use of waste fuel and lubricants on road and track surfaces.
ResponsibilitiesUptake and adherence to guidelines depends upon farmer and general community involvement and willingness to cooperate. Regulations relating to storage are the responsibility of the Department of Minerals and Energy while local by-laws will require a commitment from the Shire of Wyndham East Kimberley. Farmer groups, Department of Agriculture and the Shire of Wyndham East Kimberley should be involved in developing and effectively delivering improved educational material about fuel storage and the safe handling of waste products.
ReferencesAustralian Standard ®, The storage and handling of flammable and combustible liquids, AS1940-1993, Standards Australia.
Guidance Note S308 REV 3, (1998) Tank Installations for the Storage of Flammable and Combustible Liquids, Department of Minerals and Energy – Explosives and Dangerous Goods Division.
Guidance Note S319 REV1, (1998) Storage of Dangerous Goods on Farming Premises, Conditions for Exemption from Licensing, Department of Minerals and Energy – Explosives and Dangerous Goods Division.
Sugar Mill Goals
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A sugar mill that always operates at or above Australian Best Management Practices for the management of by-products.
When the sugar industry was set up in Kununurra, it was decided that the mud that entered the sugar mill on the cane would be transported back to the farms via the M1 Irrigation Channel. However, this caused management problems for the millers, the farmers and the water delivery operators (Ord Irrigation Cooperative). In 1999 the mud was removed from the channel and stockpiled on land adjacent to the mill. While this has improved the quality of the irrigation water the industry has still to deal with problems associated with disposal of by-products from the milling of sugarcane (boiler ash, mill mud and bagasse).
Current StatusMill mud, boiler ash and surplus bagasse are now stockpiled on land adjacent to the mill. The cooling water is returned to the channel and this water is now of a quality that could be discharged directly into a natural waterway.
The licensing requirements from the Environmental Protection Authority have been eased with the only water sampling requirement now being to sample the channel monthly for Biological Oxygen Demand (BOD), and for one sample run per year where the full suite of parameters are tested. In previous years the sampling requirements where more stringent – however after proving that the cooling water is not a threat these requirements have been eased.
The ash is now pumped into settling ponds, before being removed and stockpiled on adjacent land by a contractor. These ponds may be having a negative impact on the quality and depth of the ground water in the area.
The mud is now partially dried before being stockpiled for removal by a contractor, some of this is being returned to farmland. The demand for the mud is increasing and there does not seem to be any foreseeable problems with disposing of the mud (Russel Kirk pers com)
A business making compost is being developed around the disposal of mud, ash and bagasse. Trials have been conducted to test the quality of the composted product. The plan is to use all of the mill mud, some ash and some bagasse within 3 years. The sugar industry bears the cost of removing unwanted by-products from the mill site, a cost that is likely to increase in the short term as the land adjacent to the mill becomes filled with ash, bagasse and surplus mud.
Knowledge Gaps-
Identify the benefits to farmers from use of the mud, ash and compost.
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Develop methods of applying, spreading and managing these by-products on farm.
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The impacts of the ash drying dams on the ground water.
Ensure that all by-products are returned to farm by:
1. Developing the market for them through more information about how to use them cost effectively.
2. Encouraging the production and use of compost.
Strategy 2Reduce the level of by-products by:
1. Improving management methods that reduce the amount of mud being brought to the mill.
2. Developing new varieties of cane that have lower fibre levels and thus produce less bagasse than existing varieties.
Strategy 3Monitor the ground water levels and quality around the ash settling and drying ponds.
ResponsibilitiesThe sugar industry has already taken responsibility for the costs associated with removing by-products from the mill and both the miller and growers have responsibility for further encouraging the return of by-products to the farms. The sugar industry also has a responsibility for investigating the impacts that they are having on the ground water in the immediate area around the ash drying dams.
There is a need for some basic research into the management of by-products on farm and while the sugar industry should bear this cost assistance from research providers like Department of Agriculture will be necessary to achieve maximum uptake. Research providers such as Department of Agriculture, CSIRO and BSES should continue to be responsible for developing new varieties with lower fibre content. Funding for this research is likely to come from joint industry and government support through the Sugar Research and Development Corporation and Department of Agriculture.