Thursday, March 28, 2013

New Research to Boost Water Recycling in South Australia

Australia is a dry continent, and with climate change, expected to get drier, in general.

Boosting use of recycled water in agriculture is a critical part of the equation as water efficiency becomes critical and squeezing more out of each litre of water becomes a  more normal issue in Australia.  Israel already boasts of getting at least two uses out of each litre of water.......Australia is a long way behind that claim.

But some recently funded research is at least examining options to boost recycled water use while managing salt, a critical problem in drier areas of Australia, although not so important in the wetter areas of the north......we do not even do much water recycling, and some utilities seem to not care much about water recycling with the PAWC in the NT one of the worst in Australia with very low percentages of effluent recycled.

Maybe if this new research shows promise we shall all be drinking wine made from grapes grown in McLaren Vale on recycled wastewater.

The new research to expand the use of water recycling for irrigating South Australia’s vineyards has been initiated by the Australian Water Recycling Centre of Excellence.

Led by the South Australian Research and Development Institute (SARDI) at the Waite Institute, and co-funded by the Goyder Institute for Water Research, the project is collaborating with the local viticulture industry and the University of Adelaide to demonstrate the economic and environmental value of water recycling to Australia’s agrifood industry.
In announcing the project, Australian Water Recycling Centre of Excellence CEO Dr Mark O’Donohue said the security of water supply is an ongoing concern for producers of horticulture crops.

“Recycled water can provide a secure, climate-resilient water supply for many agricultural areas of Australia. This project will contribute to a growing body of knowledge about how to incorporate the use of recycled water into a variety of irrigation regimes,” said Dr O’Donohue.
Project investigator Tim Pitt, from SARDI, said, “The project involves crops being watered under very precise irrigation systems and looks at how to mitigate the salt content of recycled water by diluting it with fresh rainwater. We will be applying recycled water to vineyards in the McLaren Vale [region] and to almond orchards on the Northern Adelaide Plains.”

The trials at a McLaren Vale vineyard, owned by Treasury Wine Estates, will test whether redirecting rainfall - from raised soil mounds built between the vines to soil directly under vines irrigated with recycled water - reduces the build-up of salt. Preliminary studies indicate that redirecting rainfall run-off to drip lines can reduce the salt content in vine leaves and grapes by 20 to 30%.
The almond orchard trials will use mixtures of recycled water and freshwater to identify the most salt-sensitive growth stages of almonds. Such knowledge will have value to producers, water utilities and policy makers trying to maximise the use of recycled water in agribusiness. “We will also assess how the changing concentrations of salt, in the various soils being assessed, affect plant response in terms of vigour, yield and crop quality,” said Pitt.

Based on the success of the trials, the horticulture industry could expand its use of recycled water schemes for precision crop irrigation in other dry regions and improve management of soil salinity.
This is very clever - crafty use of both commodities of water with the more precious fresher water being used to help flush salt through the system, especially near the rootzone along the row.
It matches work that has shown that organic mulches in the rootzone along the row also improve production and reduce water use.
Combining these two factors could lift water use efficiency quite significantly in wine grape areas.

In our region near Darwin, neither of the two issues - quality production and use of organic residuals in horticulture [ but some goes into home gardens] nor effluent recycling and reuse are widely used.
Yet, we have 35 - 40 weeks each year without rain, where irrigation must be used in both urban and rural areas including horticulture, to enable growth of plants.  Most of that is supplied from groundwater, with an annual recharge the next rainy season, in most areas.  But many have some ancedotal evidence that water tables are declining.
Could we do better?

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