Reuse: Agriculture
Content Table
Agronomic and water quality considerations
Water use for agricultural irrigation is the largest component of water use in most countries and is more than 70% of human water use in drier countries. Use of recycled water for irrigation requires consideration of soil types, groundwater levels, soil and water chemistry, nutrient loads, limits on chemicals, the salt tolerance of crops, the leaching of salts, and management of drainage water.
Various crops can be irrigated with recycled water. The water quality required depends on the crop type and the irrigation method. Higher quality recycled water is required for irrigation of crops which are eaten uncooked.
has provided a convenient use for recycled water and avoided the need for more costly discharges to receiving waters.
Irrigation of pastures
In many countries, irrigation of pasture land close to treatment plants
Irrigation of field crops
Examples of recycled water use in field crops include:
· At Mendoza in Argentina, recycled water is used for irrigation of forest, olive trees, fruit trees, alfalfa and other crops over an area of 3640ha.
· In Israel, about 130 million m3/year of recycled water from Tel Aviv is used for unrestricted irrigation in the Dan Region project after aquifer storage and recovery.
· Jordan uses about 70 million m3/yr of recycled water for agricultural irrigation.
· Kuwait uses about 120 million m3/yr of recycled water for agricultural irrigation.
· In Tunisia, recycled water from Tunis has been used for irrigation of citrus and olive trees since 1965.
· In Australia, recycled water is used for irrigation of sugar cane crops at Mackay and Hervey Bay in Queensland.
Irrigation of horticultural crops
Examples of recycled water use for horticultural crops include.
· In the Monterey District in California, recycled water from Monterey is used for the irrigation of high value vegetable crops including artichokes, asparagus, broccoli, carrots, cauliflower, celery, lettuce, spinach and strawberries. Until the 1980s, groundwater was the main source of water for irrigation but drawdown and seawater intrusion reduced available supplies. Extensive field trials of irrigation with recycled water commenced in 1980 and were completed in 1985. The trials demonstrated that irrigation of food crops with recycled water was safe. The regional water recycling scheme which began operating in 1988 irrigates about 4700ha of food crops using about 25 million m3/yr.
· In South Australia, up to 120,000 m3/day of recycled water from Adelaide is used for irrigation of vegetable crops in the Virginia area north of Adelaide. Recycled water from Christies Beach south of Adelaide is used for irrigation of vineyards.
Other irrigation applications
Other irrigation applications of recycled water include:
· Plant nurseries,
· Tree plantations,
· Aquaculture.
Low technology irrigation
While regulations in the developed countries call for the best technology and high standards of treatment for recycled water used in agriculture, many developing countries have insufficient income to install high- technology treatment systems. The World Health Organisation has therefore developed Guidelines for the Safe Use of Wastewater, Excreta and Greywater. The WHO Guidelines provide guidance on achieving public health protection using low-technology treatment systems coupled with application controls (non-spray, drip or subsurface irrigation), harvesting controls (withholding periods before harvest and washing after harvest), and farm worker hygiene measures.
Tula Valley, Mexico: Wastewater from Mexico City flows north into the Tula Valley. The wastewater settles in a large detention storage before being drawn for irrigation of field crops and vegetables crops. The total area irrigated is about 90,000ha. A side benefit is the recharge of local groundwater aquifers by percolation.
Related Articles
Recent Papers on Reuse in Irrigation and Agriculture
References
Asano, T. et al (2007) Water reuse: issues, technologies and applications, McGraw-Hill New York, ISBN-13: 978-0-07-145927-3, Part 4: Water Reuse Applications
- Chapter 17: Agricultural Uses of Reclaimed Water;
WHO (2006) WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater, 4 vols, World Health Organisation, Geneva ISBN 92 4 154686.
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