Salt-degradation in India's Indo-Gangetic Basin could have resulted in an estimate 20 to 40 per cent increase in human health problems and 15 to 50 per cent increase in animal health problems, besides crop yield losses, according to a new UN study.
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.
The United Nations University's Canadian-based Institute for Water, Environment and Health found that 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.
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.
In India's Indo-Gangetic Basin, 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 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.
Even in the US's Colorado River Basin, studies show the annual economic impact of salt-induced land degradation in irrigated areas at USD 750 million.
"It is important to note that the above numbers on global cost of salt-induced land degradation refer to economic losses based on crop yield losses only," according to the paper authored by eight experts based in Canada, Jordan, Pakistan and Sri Lanka.
"However, the crop yields from irrigated areas not affected by salinisation have increased since 1990 due to factors such as improved crop varieties, efficient on-farm practices, better fertiliser use, and efficient water management practices.
"Consequently, there may be larger gaps in crop yields harvested from salt-affected and non-affected areas under similar agro-ecosystems, suggesting an underestimation of the economic cost of salt-induced land degradation," the paper added.
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 region and the US.
