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FEATURE ARTICLE: WATER EFFICIENCY IN SOUTH AUSTRALIA'S VINEYARDS
Methods of Irrigation
The water efficiency of vineyard irrigation varies with the method used. Drip or microspray methods are highly efficient, as tubes or pipes drip water slowly onto crops, leading to less water being lost through evaporation. Spray methods, which are subject to greater evaporation and are less targeted, are generally considered less efficient than drip or microspray. Furrow or flood irrigation is regarded as the least efficient method in most circumstances (South Australian Wine Industry Association 2004).
The most commonly used methods of irrigation in all states and territories are the drip or microspray methods, which experienced an increase in all states and territories from 2003-04. South Australia has consistently had the highest estimated proportion of vineyards watered via this method. Spray (excluding microspray) use has decreased in all states and territories, particularly in New South Wales and Victoria. Use of the furrow or flood method is decreasing in all states, with South Australia reducing the use of this method to 0.8% in 2007-08, around half of the 2003-04 level.
Since 2003-04, the use of drip or microspray irrigation methods in South Australia has steadily increased (reaching 86.2% in 2007-08), and continues to be above the Australian average (81.0%).
The furrow or flood method involves gravity distributing water to where it is required, through virtual flooding of cultivated land. Although a cheaper option in terms of labour costs, more water is lost to evaporation via this method especially in times of drought. A tightening of water allocations over the last two years may have contributed to the large decrease in use of the furrow/flood method as irrigators convert to more water efficient options.
All states and territories have shown a decline in furrow or flood methods of irrigation since 2003-04, while South Australia has consistently irrigated under 2.0% of vineyards in this manner, markedly below the national average (6.3% in 2007-08). New South Wales has recently shown a sharp decline in this method of irrigation, but still remains well above South Australia in 2007-08.
Quantity of Water Used
South Australia's total water usage for vineyard irrigation has decreased from 200,000 megalitres in 2003-04 to 189,000 ML in the 2007-08 period, although a slightly greater proportion of vineyards were irrigated in 2007-08. This is due to the quantity of water being used per hectare of vineyard reducing from 3.2 ML/ha in 2003-04 to 2.7 ML/ha in 2007-08. South Australia's water usage per hectare over the period has consistently been lower than for Australia as a whole.
Despite lowered water allocations, less water being used for irrigation, the current drought conditions, and less wine being produced overall, South Australia has continued to produce at least 46.0% of the country's wine. After a season of low production in 2006-07, South Australia produced 572,870ákL (46.0%) of Australia's 1,244,776ákL of wine in 2007-08.
Current drought conditions have had a significant impact upon water allocations for vineyard irrigators. The proportion of vineyards being irrigated has increased in all states and territories since 2004-05 aside from New South Wales. The most common method of irrigation for all states and territories is the drip or microspray method which is more water-efficient than other methods, such as furrow or flood. South Australia has consistently had the highest proportion of surveyed vineyards watered via drip or microspray across each financial year since 2003-04, and the lowest usage of furrow or flood methods.
Water used for irrigation of each hectare of vineyards in South Australia has fallen during the 2003-04 to 2007-08 period, down to 2.7áML per hectare in 2007-08, while remaining consistently lower than Australia as a whole.
LIST OF REFERENCES
ABS (Australian Bureau of Statistics) 2008, Australian Wine and Grape Industry 2008, cat. no. 1329.0, ABS, Canberra.
Bureau Of Meteorology 2008, Special Climate Statement 16, viewed 8 May 2009, <http://www.bom.gov.au/climate/current/statements/scs16.pdf>.
Industry Partnerships Programme 2006, The Australian Wine Grape Industry: Taking Stock and Setting Directions, Final Report, viewed 8 May 2009, <http://www.pir.sa.gov.au/__data/assets/pdf_file/0009/48447/TSSD_final_report_27Dec20061.pdf>.
PIRSA (Primary Industries and Resources SA) 2008, PIRSA Grape and Wine Scorecard Report 2007-08, viewed 8 May 2009, <http://www.pir.sa.gov.au/__data/assets/pdf_file/0015/91230/Wine_Scorecard_2007-08.pdf>.
South Australian Wine Industry Association 2004, Australian Wine Industry State of the Environment 2003, viewed 10 June 2009, <http://www.wfa.org.au/PDF/Environment2003.pdf>.
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