Large areas of rich irrigated and fertile land in the Indo-Gangetic basin is being lost daily to salt damage, confirms the UN.
Crop yield losses on salt-affected lands for wheat, rice, sugarcane and cotton grown on salt-affected lands could be 40 per cent, 45 per cent, 48 per cent, and 63 per cent, respectively. Employment losses could be 50-80 man-days per hectare, with an estimate 20-40 per cent increase in human health problems and 15-50 per cent increase in animal health problems in India’s Indo-Gangetic Basin.
Scientists have now confirmed that salt-spoiled soils worldwide is 20 per cent of all irrigated lands, an area equal to France.
According to the UN University’s Canadian-based Institute for Water, Environment and Health, 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.
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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
Zafar Adeel, director of UNU-INWEH
Today an area the size of France is affected, about 62 million hectares (20 per cent) of the world’s irrigated lands, up from 45 million hectares in the early 1990s.
Salt-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.
“To feed the world’s anticipated nine billion people by 2050, and with little new productive land available, it’s a case of all lands needed on deck,” says principal author Manzoor Qadir, assistant director at the Institute. “We can’t afford not to restore the productivity of salt-affected lands”.
Zafar Adeel, director of UNU-INWEH, notes the UN Food and Agriculture Organization projects a need to produce 70 per cent more food by 2050, including a 50 per cent 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, Indus Basin, Yellow River Basin, Euphrates Basin, Murray-Darling Basin, Indo Gangetic Plain and San Joaquin Valley.
The estimated cost of crop losses was drawn from a review of more than 20 studies over the last 20 years in Australia, India, Pakistan, Spain, Central Asia and the USA.
Globally, irrigated lands cover some 310 million ha, an estimated 20 per cent of it salt-affected (62 million ha). The inflation-adjusted cost of salt-induced land degradation in 2013 was estimated at $441 per hectare, yielding an estimate of global economic losses at $27.3 billion per year.
In the Indus Basin in Pakistan, wheat grain yield losses from salt-affected lands ranged 20-43 per cent with an overall average loss of 32 per cent. For rice, the crop yield losses from salt-affected lands ranged 36-69 per cent with an overall average loss of 48 per cent.
“These costs are expected to be even higher when other cost components such as infrastructure deterioration (including roads, railways, and buildings), losses in property values of farms with degraded land, and the social cost of farm businesses are taken into consideration. In addition, there could be additional environmental costs associated with salt-affected degraded lands as these lands emit more greenhouse gases, thus contributing to global warming”.
