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FSA Consulting has completed a project to develop indicators of sustainability for effluent reuse in the intensive livestock industries piggeries and cattle feedlots. Australian Pork Limited, Meat and Livestock Australia and NSW EPA jointly funded the project.
There is currently a significant amount of work being undertaken both in Australia and overseas. It is anticipated that the findings of these studies will improve the general understanding of reuse. Recommendations are also made for possible future research to better understand the processes.
The study has identified sustainability indicators for a number of parameters: nitrogen, phosphorus, salinity and sodicity. For these sustainability indicators, trigger values have been identified to assist industry in reviewing their effluent and manure reuse forward plans. The monitoring and review of performance using these sustainability indicators will assist industry with operating environmentally sustainable operations.
Following are recommendations for the sustainability indicators:
- For nitrate-nitrogen, a limit of 10 mg/L below the active root zone is suggested only as a trigger for further investigation. For nitrogen, sustainability of reuse practices depends also on the risk of nitrate moving off-site in stormwater runoff and by leaching to groundwater, the quality (value) of the groundwater and the amount of deep drainage of the soil of the reuse area. These need to be evaluated as part of the risk assessment of the reuse area.
- For phosphorus, it is recommended that storage of phosphorus be allowed based on the calculated storage capacity from the phosphorus sorption isotherm, at a soil solution concentration of 0.5 mg/L. However, this soil solution concentration needs review as the recent work of Redding and others emerges. Other soil solution concentrations may be appropriate for different soil types and regions depending on available data. Another test that offers potential is the simple test for estimating phosphorus buffer capacity (PBC) that was developed by Burkitt et al. (2002). Their methods provide a simple and accurate method for estimating PBC. However, this work requires further evaluation to ascertain whether their data can be used to provide simple indices for determining phosphorus sustainability of a range of soil types, not only in NSW, but for the cropping soils of Australia in general.
A risk assessment process has also been developed. This risk assessment process considers the site assessment, the whole farm nutrient mass balance, the design and management of the reuse area and the sustainability indicators to decide if adverse environmental impacts are likely. The outcome of the risk assessment process is a risk appraisal for each resource and targeted environmental monitoring to measure sustainability.
No recommendations are made concerning the application (or not) of Load Based Licensing to piggeries and cattle feedlots and the application of the currently existing Load Calculation Protocol to piggeries and cattle feedlots. This process needs to be negotiated between the industries involved and the NSW EPA.
Currently licensed piggeries and cattle feedlots in NSW have collected significant monitoring data. This collected information could be used to trial the developed risk assessment process. As part of this current study, three theoretical risk assessments have been completed to further explain how the process would work. A further trial of the risk assessment process could include a range of case studies on real piggeries and feedlots to demonstrate how the assessment process would work and the outcomes that it would deliver in terms of the assessed risk and the resultant monitoring requirements. This would allow the process to be properly evaluated for both the piggery and feedlot industries. Theoretical example risk assessments for a piggery and two feedlots are included in the appendices.
The Load Calculation Protocol proposes a 15 year forward management plan with a review of the plan every 3 years to ensure that future planned application rates will continue to achieve sustainable assimilation. FSA Environmental agrees that there is a need for a plan for managing nutrients for reuse. Review via monitoring results at least every three years is necessary to judge performance. Plans for proposed reuse should consider monitoring results. Whether a 15 year forward management plan is strictly needed is debatable. The main priority should be a forward plan that is regularly reviewed and updated in light of monitoring results.
The cattle feedlot industry agrees with the 15 year forward management plan. FSA Consulting re commended that if the pig industry wishes, they adopt a 5 - 10 year forward management plan that is regularly reviewed.
The general recommendations for sustainable reuse presented in the report apply to most industries that reuse their by-products in a land application system. However, inherent differences will apply for industries that generate larger volumes of water compared to piggeries and cattle feedlots. These, and any other differences would need to be evaluated when considering the application of these sustainability indicators to other industries.
It is recommended that EPA review their monitoring requirements for piggeries and cattle feedlots. The level of monitoring required should be based on the level of environmental risk as determined by the risk assessment process. The level of environmental risk specific should also determine the parameters measured.
The authors believe that a defined path for upgrading Codes of Practice and Guidelines is lacking, with many of these documents being outdated and/or very conservative because of a lack of knowledge 'Precautionary Principle'. This is however, changing with many of the more recently produced codes for intensive animal industries planning 5-year reviews and upgrades of the publications. It would be beneficial that as part of current and future research (APL and MLA), relevant, peer reviewed findings be included in regular upgrades of codes and guidelines. This is most likely to be successful if national codes and guidelines exist for the industries. This process can proceed, as the feedlot industry currently has a National Code and the pig industry is developing a National Guideline.
The sustainability indicators identified from this project are considered to be the best available at the time of project completion. However, due to the significant work being undertaken currently in this area, particularly by the piggery and feedlot industries, it is recommended that they be regularly reviewed to ensure they remain relevant.
FSA Consulting advised that it is important that the NSW EPA and operators of piggeries and cattle feedlots recognise that it is extremely difficult to develop tools for determining and demonstrating sustainability and indicators of sustainability that adequately cover all situations. It is probable that situations will arise where the tools for determining sustainability overstate the likely risk to the environment. Similarly, while the best-bet indicators of sustainability have been identified in this project, these may occasionally provide an inaccurate assessment of environmental impact. Consequently, where a significant level of environmental risk or impact is identified, it is critical to confirm that the result is accurate through further examination.
A copy of the project report is available from:
Australian Pork Limited, Deakin West ACT 2600
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Quote the Project Reference Number:
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