Urease activity in cultural layers at archaeological sites

Urease activity in soils and cultural layers at medieval settlements located within the Kislovodsk basin (Northern Caucasus, Russia) was studied to reveal the sites of cattle keeping and the areas of ancient manured lands. Input of various organic materials increases a microbial biomass and enzymatic activity in soils. In particular, urease activity increases in soils with long-term amendment of manure, compost, and other organic residues due to the improvement of soil fertility and income of ureolytic bacteria together with organic fertilizers. Soil urease activity was estimated in two different zones within Alanic settlement (AD 200-400). In cultural layers of the zone with ruined walls remains urease activity was almost twice higher than in those of the second zone without walls remains. The results demonstrated that buildings of the settlements were used as cattle pens. In the vicinity of other Alanic settlements (AD 500-800), urease activity decreased with distance from settlements. Comparison of urease activity, pottery scattering, and soil phosphorus content made it possible to mark the boundaries of ancient manured lands. The parameter of soil urease activity may be useful in revealing the infrastructure of settlements, sites of cattle keeping, and areas of ancient arable lands.