14
plane washout in the mountains, have a great influence on weathering and soil
formation.
Artificial irrigation is an important factor in soil formation. Long-term irrigation
had a beneficial effect on the soils of the oases, but led to salinization and waterlogging of the surrounding lands. The destruction of natural vegetation in deserts
caused soil deflation in sandy areas, and the destruction of trees and shrubs in the
mountains and foothills led to increased erosion and steppe formation of forest soils.
The climatic conditions of soil formation on the plains of Central Asia change
from north to south. In this regard, the steppe chernozem soil zone of the far north
of Central Kazakhstan is replaced to the south by a zone of chestnut soils and then
a zone of brown desert-steppe soils.
The desert plains in Central Asia belong to the zones of gray-brown soils (northern and southern), where, by the diversity of parent rocks, various soils are distinguished, which belong to the types of gray-brown soils, takyr soils, and takyrs. In
the southern half of the desert zone, in ephemeral deserts, and in the semi-deserts of
the foothill plains and foothills, typical gray soils are widespread (Gvozdetsky and
Mikhailov 1978).
In the mountains in Central Asia, the following altitude zones are distinguished
(Gvozdetsky and Mikhailov 1978):
1) desert steppe, with the corresponding subtypes of brown and gray earth soils;.
2) Dry steppe with mountain chestnut, dark gray, and brown soils;
3) forest-meadow-steppe with various soils – mountain-brown, mountain-forest
brown, dark-brown and dark-colored, mountain chernozems;
4) mountain-meadow and meadow-steppe soils with different subtypes of subalpine mountain-meadow and meadow-steppe soils;
5) high-mountain meadow, meadow-steppe, desert-steppe, desert takyr-like, and
dry tundra soils;
6) zone of perennial snows and glaciers.
In the altitudinal zonation of the soil cover, there are large differences between
the northern and southern ridges, between better- and worse-moisturized parts. The
altitude boundaries of these zones are also not the same. These determine the existence of different spectra of altitudinal zoning. The zones are not equally well
expressed everywhere; some of them fall out in places or are represented by isolated
areas, such as the forest-meadow-steppe zone. Certain types of soils in the highland
zone have signs of soil-forming processes, which are more common in the mountains in Central Asia.
Some soils of the desert zone, especially typical gray soils, are very fertile under
the conditions of artificial irrigation and constitute the main base of oasis agriculture, mainly cotton growing. Other desert soils are used for irrigated agriculture
after appropriate reclamation. In the desert zone, there are large areas of virgin lands
that are suitable for irrigated agriculture. Typical and dark-gray soils and some other
soils of the high-elevated foothill plains and foothills are used in rainfed agriculture.
During the development of virgin and fallow lands in Kazakhstan, large tracts of
land were plowed up in the zones of chernozem and chestnut soils.
2 Natural Conditions in Central Asia
plane washout in the mountains, have a great influence on weathering and soil
formation.
Artificial irrigation is an important factor in soil formation. Long-term irrigation
had a beneficial effect on the soils of the oases, but led to salinization and waterlogging of the surrounding lands. The destruction of natural vegetation in deserts
caused soil deflation in sandy areas, and the destruction of trees and shrubs in the
mountains and foothills led to increased erosion and steppe formation of forest soils.
The climatic conditions of soil formation on the plains of Central Asia change
from north to south. In this regard, the steppe chernozem soil zone of the far north
of Central Kazakhstan is replaced to the south by a zone of chestnut soils and then
a zone of brown desert-steppe soils.
The desert plains in Central Asia belong to the zones of gray-brown soils (northern and southern), where, by the diversity of parent rocks, various soils are distinguished, which belong to the types of gray-brown soils, takyr soils, and takyrs. In
the southern half of the desert zone, in ephemeral deserts, and in the semi-deserts of
the foothill plains and foothills, typical gray soils are widespread (Gvozdetsky and
Mikhailov 1978).
In the mountains in Central Asia, the following altitude zones are distinguished
(Gvozdetsky and Mikhailov 1978):
1) desert steppe, with the corresponding subtypes of brown and gray earth soils;.
2) Dry steppe with mountain chestnut, dark gray, and brown soils;
3) forest-meadow-steppe with various soils – mountain-brown, mountain-forest
brown, dark-brown and dark-colored, mountain chernozems;
4) mountain-meadow and meadow-steppe soils with different subtypes of subalpine mountain-meadow and meadow-steppe soils;
5) high-mountain meadow, meadow-steppe, desert-steppe, desert takyr-like, and
dry tundra soils;
6) zone of perennial snows and glaciers.
In the altitudinal zonation of the soil cover, there are large differences between
the northern and southern ridges, between better- and worse-moisturized parts. The
altitude boundaries of these zones are also not the same. These determine the existence of different spectra of altitudinal zoning. The zones are not equally well
expressed everywhere; some of them fall out in places or are represented by isolated
areas, such as the forest-meadow-steppe zone. Certain types of soils in the highland
zone have signs of soil-forming processes, which are more common in the mountains in Central Asia.
Some soils of the desert zone, especially typical gray soils, are very fertile under
the conditions of artificial irrigation and constitute the main base of oasis agriculture, mainly cotton growing. Other desert soils are used for irrigated agriculture
after appropriate reclamation. In the desert zone, there are large areas of virgin lands
that are suitable for irrigated agriculture. Typical and dark-gray soils and some other
soils of the high-elevated foothill plains and foothills are used in rainfed agriculture.
During the development of virgin and fallow lands in Kazakhstan, large tracts of
land were plowed up in the zones of chernozem and chestnut soils.
2 Natural Conditions in Central Asia