Under consideration is a regionalization version corrected with the aim to renew taxons, to give a new interpretation of farming systems and to specify the qualitative and quantitative characteristics of the soil cover in agricultural areas. It is of great interest from the historical viewpoint, permitting to study the stages in the development of the purposeful regionalization. The present data may be useful for elaborating new specialized regionalization using the modern GIS-technologies for forecasting the development of agriculture in the nearest future.

Under discussion is the FAO algorithm modified to estimate the suitability of lands and soils for agricultural purposes using the definite LUI index (land unit index). The latter is calculated by rating of soil indices taken into complete account and accepted by FAO, USDA (USA) and the Ministry of Agriculture in the Russian Federation. The algorithm and proposed computer programs of interactive expert systems ((ADAPTER, LAND, PLANT) are universal and make it possible to use the indices for solving a number of intricate tasks in off-line regime.

Chernozems under irrigation for a long period of time have been studied using the micromorphological methods. The soil porosity, the amount of microaggregates, biogeneity, humus microforms and the presence or formation of optically oriented clay were taken as the basic indices for estimating the stability of chernozems to irrigation during 30-50 years. The different ionic composition of the irrigation water serves as evidence of varying anthropogenic evolution of chernozems.

As a result of experimental studies carried out for the first time with the aim at determining the impact of black (Haloxylon aphyllum) and white Saxaul (Haloxylon persicum) on the mineralogical composition of fine-dispersed fractions in sandy desert soils, it seemed reasonable to conclude that the transformation of minerals is quite different in soils used under different Saxaul species. This is explained by differences in biogeochemical turnover of elements in soils under black Saxaul and as a consequence by a higher Na content in the litter and the soda for-mation in the soil profile. The latter serves as a cause of alkalinization of soil solutions and transformation of minerals affected by alkaline hydrolysis.

The experimental results showed the impact rendered by different rates of organic fertilizers in the kind of poultry excrements on crystallochemical parameters of minerals containing in the fine-dispersed fractions (less than 1, 1-5, 5-10 mkm). The considerable changes induced by increased rates of organic fertilizers take place in the ratio between the basic mineral phases and the crystallochemistry of minerals of the clay fraction as the most functional part of soil. One should indicate that the content of the clay fraction decreases, the layered silicates are destroyed and transformed as affected by higher rates of potassium and ammonium, fixed by mixed-layered formations with smectite pockets. The functionally inert minerals such as quartz, feldspar, plagi-oclase and mica of dioctahedral type are accumulated.

The experimental studies permitted to determine the ratio between infiltration and transpiration of the ground water in a soddy podzolic soil, that accounts for 0.3-0.6 under dried conditions of atmospheric moistening, 2.6-2.9 as an average value for many years and 2.6-2.9 under moderately wet conditions. The loss of potassium, calcium, magnesium, zinc and manganese under the grass stand was calculated as 0.95, 89.0, 37.7, 1.42 and 1.40 kg/ha/yr respectively. Due to capillarity the root layer of this soil receives 0.19 kg/ha of potassium or 20% from its loss with water infiltration, 16.4% of magnesium, 15.0% of calcium, 13.4% of zinc and 9.0% of manganese. It is shown that the water transpiration in case of the close underground water level leads to rupture of capillary links. With increasing the soil thickness in lysimeter the water infiltration and the nitrate leaching become declined both under grass and beangrass stands.