Making Every Drop Count

Feeding the world is expensive, but the bottom-line cost is water. Gareth Evans looks at how water management is making irrigation efficient.

About a fifth of all cultivated land on the planet is irrigated – and responsible for almost half of global food production – but providing high cropping intensity and enhanced harvests is thirsty work. According to European Environment Agency figures, in the EU alone agriculture accounts for an average of 24% of total water usage. And in parts of southern Europe where irrigation forms almost all agricultural demand, this share can rise to 80%.

With water resources under ever more pressure as demand rises, irrigation practices and the potential savings that could be made – in energy, as well as water itself – are increasingly coming under the spotlight around the world.

A comprehensive new International Water Management Institute (IWMI) study unveiled at 2009 World Water Week in Stockholm warned, for instance, that without major reforms in agricultural water usage, Asia will face food shortages by 2050.

Add to this the concerns of water companies over operating costs and carbon footprints, and governments over policy ahead of the UN climate summit in Copenhagen, and it becomes clear why irrigation is rising fast on political and economic agendas.

As technology, fiscal measures, environmental regulation and economics steadily converge around the issue, "make every drop count" has become more than a simple rallying slogan, but the real challenge is deciding how that goal can be achieved.

Efficient innovation

"Perhaps the simplest and most promising innovation in recent years has come from Israel."

One obvious way lies in innovation. Improving efficiency at the delivery end offers the promise of palpable benefits all the way up the pipe, back to the treatment plant and beyond, and is something irrigation specialists and water companies across the globe are getting to grips with.

In Xinjiang, China, for example, almost a quarter of a million hectares of land are benefiting from a new take on Israeli drop irrigation, developed by Xinjiang Tianye to work beneath plastic film.

Field trials have consistently shown that the system, which costs about seven times less than conventional drop-irrigation equipment, is capable of reducing water usage by up to 50% compared with traditional methods. Making the technology available cheaply opens the application to ordinary farmers and large-scale farming at home, but there may also be a ready export market among other Asian countries.

Other countries, including Australia, India and the US, as well as the EU, have been looking at the possible savings involved in irrigation technology, and often unite with commercial companies, irrigators, consultants, government agencies, universities and water providers to explore new systems. However, perhaps the simplest and most promising innovation in recent years has come from Israel, birthplace of "modern" drop irrigation and a country that already enjoys an unparalleled global reputation in the field.

Launched in May, Tal-Ya Water Technologies has brought a modern twist to an idea from the Bible: harvesting "free" water in the form of dew and condensation. Developing the idea of using of stones in the desert, the company has designed a square, crenellated tray made from a UV-stable plastic composite with aluminum and limestone additives. The trays sit around the bases of plants and cost just $1 each.

The trays' channels funnel rain, dew and condensate directly to the roots, while the bodies prevent losses by evaporation or runoff, suppress weeds and provide protection in frost-prone climates. In addition, where climatic conditions do not naturally provide sufficient water for a particular crop, sections of the tray can accommodate ancillary watering equipment to augment the supply. According to field tests by Israel's Ministry of Agriculture, these innovations can cut water usage by 50%.

'Smart' savings

Global estimates suggest only about 40% of irrigation water actually reaches its target crop, the rest being lost through evaporation and runoff. A similar problem exists in the domestic irrigation market. In the US, for example, the American Water Works Association claims householders and companies typically "over-water" landscapes and gardens by between 30% and 300%.

"Global estimates suggest only about 40% of irrigation water reaches its target crop."

As a result, many in the industry are looking to make savings through "smart" technology – systems that take environmental factors such as recent weather and climatic conditions into account when determining water dosage.

Developments in this field allow irrigation controllers to take account of factors such as soil characteristics and the type of plants being grown, with in situ sensors monitoring moisture levels, temperature and other variables in real time to optimise water supply.

It is a high-tech and international approach. Among the array of sensors, for instance, incorporated into the IrriWise system from Netafim, Israel's world leader in irrigation technology, is one made by Decagon USA, which first saw service on the surface of Mars aboard NASA's Phoenix landing craft.

Such intelligent sensing solutions can deliver significant savings. Chris Spain of US water management company HydroPoint recently quoted a $75m reduction in water cost for clients, and other evidence points to typical saving of 20% or more. On this basis the future growth of smart systems seems assured.

Policy and pricing

Although individual users, technology vendors and water companies can – and clearly are – doing a lot to reduce wastage at the sprinkler, their influence on the wider problem only extends so far. Attempts to conserve water at national or state level almost invariably require a cohesive environmental policy, coupled with a pricing structure that reflects the true cost of water use.

Although protectionism is gradually being reduced, the influence of the global market and external competition has often been buffered by agricultural subsidies, which has meant that the price paid by farmers rarely meets the full resource and environmental cost. While this might not promote wasteful practices, it may make farmers more reluctant to accept the costs involved in changing their approach.

It is not a new point. Carmen Revenga made it ten years ago in Pilot Analysis of Global Ecosystems: Freshwater Systems, which put government assistance in the western US alone at $2bn to $2.5bn per year, and she was not the first.

"Pricing is a critical part of the overall equation."

Pricing is clearly a critical part of the overall equation. Too low and there is no incentive to conserve, meaning resource security suffers; too high and food prices rise or, as has already happened in parts of China, farmers change to crops that require less water but have lower yields.

It is a difficult balancing act but in the long run, getting it right may prove as important as technological innovation when making sure every drop destined for irrigation really does count.