ABSTRACT
It has long been recognised that the operation of pedogenic processes is determined by a number of environmental factors operating through the medium of time and that these therefore determine the type of soil produced in any particular location. These ideas were originally formulated in late nineteenthcentury Russia when V.V.Dokuchaev identified the principal factors as climate, biota, parent material, relief and landscape age, and N.M. Sibertsev produced a system of soil classification based on bioclimatic zones. This system recognised that soils varied with latitude according to climatic and vegetation conditions, and gave rise to the concept of zonal soils (Table 4.1). It was also recognised, however, that these were not the only two factors controlling soil type distribution and that in some instances soils were more closely associated with parent material or drainage conditions. Such soils were termed intrazonal. A third category of soils was also recognised-azonal-to which could be assigned soils that were poorly developed, due mainly to lack of time, such as those occurring on recent alluvial deposits.
