Soil Maps

maps showing the distribution of soils on the earth’s surface and their characteristics and properties.

Depending on their content, soil maps are divided into (1) general maps, depicting the geographic distribution of classifica-tory genetic soil groups; (2) reclamation maps, showing such characteristics of soils as accumulations of salts, filtration capacity, and stone content; and (3) erosion maps, indicating the extent of erosion (or deflation) of soils, their erodibility, and areas threatened by erosion. In addition to such comprehensive maps, analytic maps, or cartograms (for example, agrochemical cartograms), are compiled. They show the distribution of the values of one or more properties of soil, for example, acidity, alkalinity, salinity, or granulometric composition.

Soil maps are divided by scale into detailed maps (1:5,000 or larger), large-scale maps (1:10,000–1:50,000), medium-scale maps (1:100,000–1:300,000), small-scale maps (1:500,000–1:2,000,000), and survey maps (1:2,500,000 or smaller).

In the USSR, detailed soil maps are compiled for experimental fields, crop-testing areas, and so on. Large-scale maps are used by farms to organize their land and in planning agrotechnical and reclamation measures. Medium-scale and sometimes large-scale maps are employed in planning agriculture and forest management on the raion, oblast, and Union republic levels. Small-scale and survey maps are used in national economic planning and for educational purposes. Soil maps of all scales are used to determine soil resources, to assess the quality and economic value of soils, and, consequently, to compare the operating conditions at agricultural enterprises. They are also used to establish soil zones for scientific and practical purposes.

Soil maps are compiled on the basis of soil surveys, whose basic principles and methods were worked out by V. V. Dokuchaev and N. M. Sibirtsev. Soil surveys include field studies to compile a list of the soils forming the soil cover, taking into account their relation to such factors of soil formation as the parent material, topography, vegetation, groundwater, and climate. The boundaries of soil contours are drawn using data obtained by aerial photography and topographic maps and verified by field work. Medium- and small-scale maps and survey maps are usually compiled by generalizing from larger-scale maps and on the basis of supplementary field work.

The first soil map of European Russia, compiled on a 1:8,400,000 scale, was published in 1851 under the editorship of K. S. Veselovskii. It was reissued on a 1:2,520,000 scale in 1879 under the editorship of V. I. Chaslavskii. Later, V. V. Dokuchaev and his students produced scientific soil maps of European Russia and a map of the soil zones of the northern hemisphere. After the Great October Socialist Revolution, soil cartography developed under the direction of K. D. Glinka and L. I. Prasolov.

The following have been compiled in the USSR: a soil map of the world (1:50,000,000, 1:60,000,000, and 1:10,000,000, published in 1937, 1964, and 1975), a soil map of the continents (1:15,000,000 to 1:25,000,000 in 1944, 1948, 1952, and 1964), a soil map of the USSR (1:4,000,000 in 1956), and a soil map of the European USSR (1:2,500,000 in 1947). The maps were compiled by the government services that issue national and regional soil maps.

Soil maps are compiled in all countries. Although they are basically alike, they vary with the national soil classifications, soil use, and the methods of improving soil. In 1974 sheets of the International Soil Map of the World on a 1:5,000,000 scale were sponsored for publication by FAO and UNESCO.