|
|
 |
 |
| |
 Printable version |
Soil degradation in the irrigated areas of the major valleys of the southern Sahara (Case of the Niger Office in Mali) |
Cahiers Agricultures. Volume 2, Number 5, 318-29, Septembre-Octobre 1993, Étude originale
|
 Résumé
Article gratuit
|
Author(s) : Roger Bertrand, Bassirou Keita, Mamadou Kabirou N’Diaye |
Summary : In most irrigated areas of the southern Sahara, poor irrigation management, the absence of efficient drainage and the growing of rice on excessively sandy soils, have led to a rapid rise in the water table and an increase in soil sodium/alkaline content and salinity. In Mali for example, the water table, originally between thirty and fifty meters below ground, now fluctuates between a depth of zero and one meter. At the Niger Office (in Mali), 50 % of the water table is now salty and occasionally very salty despite the low mineral content of the irrigation water. Even more seriously, these high sodium-containing waters have already caused increases in soil sodium content, and even alka-lization over very large areas. This results in a collapse of soil structure, porosity and permeability, which in turn reduces the mineral supply to crops and causes deficiencies, for example in zinc, and the disappearance of soil nitrogen. This can then lead to increased difficulties in the growing of foodstuffs through substantially reduced production, to a decrease in the choice of possible crops, and finally leads to plots being abandoned. Because of the important role played by these irrigated areas in the food supply of the Sahel countries, the current situation needs to be evaluated and corrective measures implemented. Solutions to prevent such soils, re-organized and rehabilitated at great cost, from becoming sterile, are briefly examined. |
Keywords : |
|
