| Résumé : |
Even an optimist would be worried if macking a survey that focused on the effects of salinity. A cross-section of literature throws up the following statements:
- Globally, soil salination is spreading at a rate estimated at 15,000 to 25,000 km²/year.
- Yields of all irrigated land - 1.2 million km² - have fallen in recent years.
- In some semi-arid countries, 10-50% of the irrigated land is affected to a greater or lesser degree, with average yield decreases of 10-25% for many crops. There are little or no time series data to allow reliable estimates of the rates of change in salinate areas; it could be 1.0 to 1.5 milion ha/year.
- 200,000 to 300,000 km² of the world's irrigated area suffers serious salination, and 600,000 to 800,000 km² are moderately affected.
- In India,Pakistan and China, 20% of irrigated land suffers from salinity. This is over and above land areas previously abandoned.
- 60% of the world's irrigated regions need upgrading to remain in good working order.
- Rejuvenating salt-covered fiels costs US$100,000 to 200,00/km², and efforts often fail.
- In the USA and Canada - a major component of the gobal breadbasket - yields are falling. It is estimated that one third of te soils in Canada now contains sufficient salts to reduce spring wheat yield by 10% or more.
More than 40 publications have been studies in the preparation of this feature, and discussions have taken place with specialists within Europe, USA and India. In addiction, information is available for verification in scientific publications, the Internet, and from organisations within the United Nations and the World Bank. |
Aller sur edunet
Accueil
The real cost of a kilo of salt in WORLD LEATHER, Vol. 18, N° 3 (05/2005)
