Every day for more than 20 years, an average of 2,000 hectares of irrigated land in arid and semi-arid areas across 75 countries have been degraded by salt, according to a new study — Economics of Salt-induced Land Degradation and Restoration — published today by the UNU Institute for Water, Environment and Health (UNU-INWEH).
Currently an area the size of France is affected — about 62 million hectares (20 percent) of the world’s irrigated lands, up from 45 million hectares in the early 1990s.
Salt-induced land degradation occurs in arid and semi-arid regions where rainfall is too low to maintain regular percolation of rainwater through the soil and where irrigation is practiced without a natural or artificial drainage system.
Irrigation practices without drainage management trigger the accumulation of salts in the root zone, affecting several soil properties and reducing productivity.
Zafar Adeel, Director of UNU-INWEH, notes that the UN Food and Agriculture Organization projects a need to produce 70 percent more food by 2050, including a 50 percent rise in annual cereal production to about 3 billion tonnes.
“Each week the world loses an area larger than Manhattan to salt degradation. A large portion of the affected areas in developing countries have seen investments made in irrigation and drainage but the infrastructure is not properly maintained or managed. Efforts to restore those lands to full productivity are essential as world population and food needs grow, especially in the developing world.”
Well known salt-degraded land areas include:
• Aral Sea Basin, Central Asia
• Indo-Gangetic Basin, India
• Indus Basin, Pakistan
• Yellow River Basin, China
• Euphrates Basin, Syria and Iraq
• Murray-Darling Basin, Australia, and
• San Joaquin Valley, United States
The paper, authored by eight experts based in Canada, Jordan, Pakistan and Sri Lanka, and published in the UN Sustainable Development journal Natural Resources Forum, details crop productivity losses at farm, regional, and global scales, the cost of doing nothing, and the net economic benefit of preventing and/or reversing land degradation.