Raising Water Productivity to Increase Food Security

by Dave

With water shortages constraining food production growth, the world needs an effort to raise water productivity similar to the one that nearly tripled land productivity over the last half-century. Since it takes 1,000 tons of water to produce 1 ton of grain, it is not surprising that 70 percent of world water use is devoted to irrigation. Thus, raising irrigation efficiency is central to raising water productivity overall.Water policy analysts Sandra Postel and Amy Vickers found that “surface water irrigation efficiency ranges between 25 and 40 percent in India, Mexico,  between 40 and 45 percent in Malaysia and Morocco; and between 50 and 60 percent in Israel, Japan, and Taiwan.”

In a May 2004 meeting, China’s Minister of Water Resources Wang Shucheng outlined for me in some detail the plans to raise China’s irrigation efficiency from 43 percent in 2000 to 51 percent in 2010 and then to 55 percent in 2030. The steps he described included raising the price of water, providing incentives for adopting more irrigation-efficient technologies, and developing the local institutions to manage this process. Reaching these goals, he felt, would assure China’s future food security.

Raising irrigation efficiency typically means shifting from the less efficient flood or furrow systems to overhead sprinklers or drip irrigation, the gold standard of irrigation efficiency. Switching from flood or furrow to low-pressure sprinkler systems reduces water use by an estimated 30 percent, while switching to drip irrigation typically cuts water use in half. Since drip systems are both labor-intensive and water-efficient, they are well suited to countries with a surplus of labor and a shortage of water. Among the big three agricultural producers, this more-efficient technology is used on 1–3 percent of irrigated land in India and China and on roughly 4 percent in the United States.

Sandra Postel estimates that drip technology has the potential to profitably irrigate 10 million hectares of India’s cropland, nearly one tenth of the total.

In the Punjab, with its extensive double cropping of wheat and rice, fast-falling water tables led the state farmers’ commission in 2007 to recommend a delay in transplanting rice from May to late June or early July. This would reduce irrigation water use by roughly one third, since transplanting would coincide with the arrival of the monsoon. The resulting reduction in groundwater use would help stabilize the water table, which has fallen from 5 meters below the surface down to 30 meters in parts of the state.

Institutional shifts-specifically, moving the responsibility for managing irrigation systems from government agencies to local water users associations-can facilitate the more efficient use of water.

Whenever price-distorting subsidies/political handouts – like free power to farmers have unintended consequences – overpumping of groundwater, the answer is alway the same. Switch from an subsidy to a voucher model, let the market do its magic, set incentives for the desired outcomes, and appoint an independent regulator to ensure compliance.

Posted via web from induslatin’s posterous

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