In order to determine the dependence for all zonal soil
types of the East European Plain of empirically determined humus horizon limit values from climatic potential, we summarized the data of numerous soil surveys.
Initially, interest was concentrated on the extensive zonal soil
types, whose diverse characteristics were formed by the prevailing climatic peculiarities and the resulting vegetation (e.
According to the majority of researchers, the variety adapted to zonal soil
and climatic conditions can provide an increase in grain yield up to 20% at no extra cost.
The crop yields on these affected soils are considerably reduced compared to those on non-saline zonal soils
The zonal soils
correspond to the phytoclimatic forest zone on the top of the hills--brown and brown illuvial soils--, and to the silvosteppe zone in the valleys--cambic chernozem and clay-illuvial soils.
For definition of hydro-physical properties of zonal soils
of the European Russia, we chose testing areas in various soil and landscape zones of the European territory of Russia [6-9].