AGROGENIC CHANGES IN HUMUS RESERVES AND THE DEGREE OF SOIL COMPACTNESS - A MAP OF 1 10 M SCALE/

The map is based on numerous factual data and demonstrates the geograp hic pattern of two major characteristics of agrogenic soils in Europea n and West-Siberian Russia (for the territories with cropland occupyin g >50% of the area). These are (1) the initial humus reserves in the 0 - to 30-cm layer (t/ha) and assessment of their changes (losses, stead y state, or an increase) as a percentage of the initial reserves and ( 2) the degree of compaction in the arable and subarable layers (0-30 a nd 30-50 cm) expressed both in terms of the absolute values (bulk dens ity, g/cm(3)) and in rating (qualitative) categories. The analysis of the spatial pattern of agrogenic phenomena in arable soils confirms th e current dehumification and describes it in detail; it also permits o ne to draw some ecological and genetic conclusions.