Improving irrigated agriculture - how far can we go?
The increasing demand for global irrigation is placing pressure on water supplies, particularly where supplies are already inadequate. Yet irrigated agriculture is needed to feed the world’s growing population. Improved water productivity is essential for future irrigated production and supply of quality food and amenities. “But how much improvement is possible?” asks Dr Wayne Meyer, Chief Scientist for the Cooperative Research Centre for Irrigation Futures (CRC IF).
The answer to this question is being explored today (16 August) at the Crawford Fund’s international development conference: “Water for Irrigated Agriculture: Finding a Flow For All” at Canberra’s Parliament House.
(The event will be opened by The Hon Alexander Downer, Minister for Foreign Affairs (9am) followed by a keynote address by Dr Frank Rijsberman, Director General of the International Water Management Institute, the worlds pre-eminent research institution on management of water for food and agriculture. A press conference will be held at 12pm in the Theatrette. The Hon. Malcolm Turnbull will address the future of Australia’s water policy at 3.35pm. Other international and national specialists will cover issues such as future water availability; climate change; and lessons and problems in regions of China, the Mekong Delta, the Indo-Gangetic Basin and Australia’s Murray-Darling)
More than one third of the world's food is produced on about 250 million hectares of irrigated land that accounts for about 80% of global fresh water consumption. The last decade has seen a disjuncture between increasing world population and area of irrigated land; new irrigation development has slowed and population growth continues unabated.
“The connection between irrigated production and the supply of food is increasingly dependant on improved productivity rather than increased area,” says Dr Meyer.
“Add to this the increased demand from urban and industrial use and for ecosystem maintenance and the pressure is on for increased irrigated agricultural productivity.”
Irrigation is an energy intensive activity that requires a systematic analysis if potential improvements are to be identified. Dr Meyer’s discussion considers opportunities and limitations to improvement from plants through to catchments, from both production and natural resource use perspectives.
“When we analyse the use of water in irrigation the first thing that is immediately obvious is that there is tremendous variability in the efficiency of use between regions, between different commodity production systems and between different managers. There are often good reasons for these differences, but as with any business every effort should be made to improve the use of resources and improve productivity,” asserts Dr Meyer.
“A major way we have improved water use productivity over the last few decades is through increased yields with better varieties and better agronomy. Within a plant species, however, the intrinsic relation between dry matter accumulation and water transpired seems to be at its genetic limit, hence there is little gain to be made.”
However, according to Dr Meyer, water productivity with crops can still be significantly improved by using irrigation systems and agronomic practices that minimise the loss of water through soil evaporation and deep drainage.
“Many of our distribution systems also have unacceptable losses through seepage, and with a current emphasis on measuring and improved control structures, significant improvements that reduce unproductive water losses are possible,” he says.
“The major limitation in applying these systems and practices is financial – in many cases there is simply insufficient return to justify the large capital and operating costs for more controlled systems.”
There continues to be a major emphasis on increasing water use efficiency.
However the relationship between plant water use and yield is such that maximum water use efficiency occurs when plants are fully supplied with water.
“In Australia, with its variable rainfall and water supply, many pasture and grain crops are not fully irrigated. This makes financial and management sense in terms of the farm business. We should therefore be cautious not to blindly pursue maximum water use efficiency as an end goal – rather we should take a more encompassing view of increasing water use productivity,” Dr Meyer says.
He explains that such productivity not only includes yield and financial returns but also community and environmental productivity. Currently there is insufficient water to satisfy all production, environmental and amenity needs so finding the best compromises is the major challenge.
“It’s about increasing multi-purpose water use productivity - a significant component of which is improving the productivity of the total irrigation system. The analysis indicates that achieving a doubling of yield at a crop level will be hard, but halving the water used is possible but expensive,” states Dr Meyer.
Further information, photos, additional press releases, abstracts and bios are available at www.crawfordfund.org or by contacting Cathy Reade, Public Awareness Coordinator, Crawford Fund on 0413 575 934.
The CRC for Irrigation Futures is a proud sponsor of the 2006 Crawford Fund Conference.
16 Aug 2006