Aridity, desertification and mistakes in management of land very often lead to so-called secondary salinization of soils. This evil is particularly pronounced in irrigated arid areas where the fertility of millions of hectares of previously productive land has already declined.
This problem is first of all of local importance. The low level of productivity of land, the decreases in food and fodder production, the losses of fields of cotton, of oil or sugar plants, of maize or wheat or millet are losses to the farmers. The first and immediate consequences of this is the lower standard of living of families in the affected regions.
Salinization and waterlogging of irrigated areas are almost inseparable; sometimes waterlogging of soils precedes salinization, and sometimes they are combined in the worst way for land and men. Waterlogging usually provokes considerable worsening of the health situation. This is known from past and present experiences in Iran, Iraq, Egypt, Pakistan, Bangladesh, and Central Asia. Waterlogging, the formation of lakes from wasted irrigation water, and the exposure of subsoil ground waters all facilitate the spread of mosquitoes and thus malaria. Potable water is becoming contaminated as well. Even houses and roads are subjected to deterioration through the influence of salts and brackish water.
Coincidence of all these phenomena at local, regional and national levels can even provoke political consequences. Everyone expects an increase of income and of food production from newly constructed irrigation systems or from newly organized irrigation state or cooperative farms. But expected prosperity is often undermined as a result of salinization. The reputations of scientists, engineers and even the intentions of governments become discredited by failures of these projects. The larger the projects and the more catastrophic the character of salinization and waterlogging, the more severe may be the socio-political consequences that can arise in the given countries. The importance of the problem cannot be underestimated. 40-60% of irrigated land is affected by salinization; not less than 20 million hectares have already been lost.
The global annual costs resulting from losses caused by waterlogging and soil salinization are on the order of 3 billion dollars and 500-600 thousand hectares. Irrigation land salinization and waterlogging are never limited to one point. If one farm suffers, then, in two-three years its neighbors will be affected, and so on. Very often salinization is not even considered. Only in-depth scientific studies can improve the forecasts of salinization before irrigation projects begin. In initiating a new local irrigation project one needs to consider the possible immediate and long-term negative consequences of salinity and to consider measures for prevention. So the need for the combating of soil salinization at the local to national levels is indisputable. Sometimes it is not fully understood by scientists, planners, engineers, regional authorities and national governments. Yet, in reality the deterioration of soil fertility, because of rapidly increasing secondary salinization, does exist and should be combatted as early as possible at the local and national levels.