AZOTOBACTER IN THE SOILS OF MOSCOW

A nitrogen-fixing bacterium has been found in the urban soils of Mosco w that is absent in the soils surrounding Moscow. Azotobacter has an u neven distribution over the city and in the soil profile. The followin g factors control its distribution: urbanogenic (high pH value, enrich ment of urbanozems with organic matter, P, K, Ca, and heavy metals), n atural (low pH value, gleying of soil horizons, physical properties of the soils), and historical (buried horizons of garden soils, shallow embedding of marble and calcareous foundations of monasteries and esta tes or the alkaline products of their weathering). Azotobacter can be used as an indicator of urbanogenesis.