LOWERING OF THE HUMUS CONTENT OF CHERNOZEM SOILS OF THE RUSSIAN PLAIN AS A RESULT OF HUMAN ACTION

The article surveys the extent and causes responsible for reduction in the humus contents of fertile chernozem soils in the European USSR. Comparison of a soil humus map compiled by V. V. Dokuchayev in 1883 with contemporary soil maps permits compilation of a map showing areas of most intensive humus loss over the late Tsarist and Soviet periods. Although the entire chernozem belt exhibited some degree of humus reduction, maximum losses have occurred in upland areas throughout the belt and in its eastern portion (translated by Andrew R. Bond).