Recycled water has a place in horticulture

Land & Water Australia. 2010. Recycled water has a place in horticulture . [Online] (Updated November 29th, 2010)
Available at: http://lwa.gov.au/node/3794 [Accessed Thursday 1st of March 2012 07:28:33 AM ].

15 November, 2010
National Program for Sustainable Irrigation

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Kristen Stirling and Anne-Maree Boland (RMCG)

Recycled water is a safe and sustainable water source for the production of horticultural crops as demonstrated by the success of numerous recycled water schemes across Australia. With an understanding of the issues associated with recycled water use and how these can be managed, the benefits of securing an alternative high reliability water source can be realised.

Recycled water is used extensively by both the amenity (parks, gardens, golf courses) and production (vegetables, fruit, grapes) horticultural sectors. Individual commodities have slightly different requirements around the use of recycled water; however, the principles (as described below) are common to both sectors.

Benefits of Recycled Water Use

There are a number of benefits associated with the use of recycled water for irrigation of horticultural crops. These include:

Increased supply of high security water (to assist with the scheduling of crops and providing confidence in meeting customer demands)
Additional nutrients (potential reduction in fertiliser inputs)
Environmental benefit (the level of nutrients and other contaminants entering waterways is reduced and the use of ‘fit for purpose’ water of a lower quality, ‘frees’ potable water for high quality needs)

The key to recycling is to match the quality of a water source to particular uses while ensuring health and environmental standards are met. The national guidelines for recycled water use have recognised that the range of industries seeking to use recycled water has increased, and that there is likely to be a diversity of water quality requirements depending on the end use of that water. The guidelines (NRMMC and EPHC 2006) promote a ‘fit for purpose’ approach, which implies that the quality of the water is appropriate for its intended use and does not pose significant risk to human health and the environment.

The primary hazards of concern that pose risk to the environment include: boron, cadmium, chloride disinfection residuals, hydraulic loading, nitrogen, phosphorus, salinity and sodium. These hazards also generally align with the major agronomic management issues for irrigation of horticultural crops with recycled water, which are: salinity (sodium and chloride), soil sodicity, nutrients (nitrogen and phosphorus) and managing algae in on-farm storage of water.

Key principles for horticulture

A number of principles have been described for irrigation of horticulture. While these principles were developed for production horticulture they equally apply to the amenity sector.

Planning: Ensure markets will accept the produce, that all regulations are understood and complied with and that management will satisfy any additional requirements (e.g. identifying recycled water and keeping it separate from other sources, preventing public access and avoiding algal blooms in any storage dams).

Water quality: Ensure the water will be of satisfactory quality regarding nutrients, salinity, pathogens and other contaminants.

Irrigation management: Determine if special measures will be needed for irrigation, e.g. additional filters, steps to avoid spray-drift, drainage management and any withholding periods.

Soil management: Make provision to monitor salinity and plan to avoid problems (e.g. by using salt-tolerant plants, shandying water with less saline supplies or leaching excess salts) and be ready to deal with sodicity (e.g. by applying gypsum).

Fertilisers and nutrients: Prepare a nutrient budget and fertiliser plan to optimise plant performance and minimise environmental impacts.

Using recycled water as an alternative water source, or to supplement existing water sources, may not be a feasible option for all horticultural producers. Consideration of the ability to match supply with demand, the quality of the water, the cost and the need to potentially modify some management practices should be made before considering a proposal to use recycled water.

Further resources

The documents listed are readily available on the websites and in some case hard copies can be ordered. The websites provide a wealth of information on issues related to the use of recycled water.

NPSI Publications

Recycled Water Publications

Irrigation Publications

Recycled water: How good should it be? Irrigation Australia Vol. 24, No. 2 (PDF)

Environment Protection and Heritage Council Publications

Australian Guidelines for Water Recycling: Managing Health and Environmental Risk

Websites

Caption: Strawberries grown with recycled water.

Citation

id: 3794 / created: 15 November, 2010 / last updated: 29 November, 2010