Study of Land Degradation Processes and Possible Rehabilitation Methods
in Arid and Semi-Arid Zones of Tajikistan

Inom Normatov

Director Institute of Water Problems, Hydropower and Ecology Academy of Sciences, Tajikistan
e-mail: owp@tojikiston.com

Abstract

It is well known that irrigation radically changes the soil processes. First of all, the water and thermal regimes of soils are changed, which affects all soil processes and properties of irrigated soils. Sufficient moistening, systematic processing of soils and deposition of fertilizers promote the increase of biological and physicochemical activities and the intensity of soil processes. Irrigation promotes a more pronounced humus horizon (in contrast with non-irrigated soils), an enhanced clay deposit in the soil profile, the blurring of boundaries of soil horizons, the destruction of carbonaceous new formation and the appearance of a number of other features, characteristic for irrigated soils. Ancient irrigated soils differ clearly from non-irrigated ones.  They are characterized by an accumulation of agro-irrigation deposits, of which the power can reach a depth of 1-5 m. In these conditions, the special type of cultivated irrigated oases soils are formed, which, as a rule, are characterized by their high fertility. They are the "golden fund" of land resources.