Sierozem


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sierozem

[′sir·ə‚zem]
(geology)
A soil found in cool to temperate arid regions, characterized by a brownish-gray surface on a lighter layer based on a carbonate or hardpan layer.

Sierozem

 

a type of soil that forms beneath subtropical semi-desert vegetation. Sierozems form under conditions of a none-lutriate and exudate water regimen on loesses, loess-like loams, and ancient alluvial deposits containing gypsum, carbonates, and salts that are readily soluble. An annual cycle of soil formation is typical. During the active spring phase, vegetation develops intensively owing to the autumn-winter accumulation of moisture in the soil. In addition, plant remains accumulate in the upper horizons and turn into humus, and some of the carbonates and mineral salts move down to lower horizons. In the summer the humus substances are mineralized, and the readily soluble salts rise to the top horizons with capillary moisture. The following sierozem horizons are identified: A (the humus horizon), B (eluvial carbonates), and C (parent material). Horizon A, which contains 1–4.5 percent humus and is 40–100 cm thick, is gray or yellow-gray in color and has a lumpy texture. Below horizon C, at a depth of 1.5–2 m, the readily soluble salts accumulate.

Sierozems are marked by good water-physiological properties, high biological activity, and adequate fertility; they produce high yields when irrigated. There are various subtypes: light, conventional (standard), dark, and northern.

Sierozems are common in Southwest Asia, North America (the southwestern United States and northern Mexico), North Africa, and Australia. In the USSR they are found in Middle Asia. Light and conventional sierozems are used in irrigation farming (cotton, sugar beets, grain crops, orchard crops, and grapes). The most ancient centers of irrigation farming have been discovered in sierozem regions.

REFERENCES

Rozanov, A.N. Serozemy Srednei Azii. Moscow, 1951.
Minashina, N. G., A. N. Rozanov, and S. A. Shchuvalov. “Pochvy.” In Sredniaia Aziia. Moscow, 1968.

N. G. MINASHINA