This paper presents a study aimed at determining the soil’s biological activity using its enzymatic activity and the ability of urban soils to self-heal in various territories of the Lankaran Region, Azerbaijan. Results revealed microorganisms decreased to 2.0-1.0-0.8×10⁶/g soil at the depth of 70-80-100 cm in light and ordinary subtypes of gray-brown soils. In cultivated variants of these soils under grain crops, a similar trend was dominant, with a decrease recorded in the total number of microorganisms from 4.8-4.0×10⁶/g soil in upper horizons to 2.2-1.5×10⁶/g soil in lower horizons. In the composition of microorganisms in the soil of virgin origin and cultivated cenoses, non-spore-forming bacteria (74.9% and 75.3%) and actinomycetes (24.8% and 24.3%) predominated. However, in small-sized fungi and spore-forming bacteria, there existed a slight difference of 0.5% and 0.3% and 18.8%–25.1%, respectively. In irrigated variants of these soils, the humus content decreased quite moderately, from 2.09% in the upper layers (0–10 cm) to 1.35% in the lower layers (50–70 cm). The average number of microbiota in the 0–100 cm layer of the studied gray-brown soils varies around 4.1-3.7-1.8-3.5×10⁶/g soil.

Keywords: Anthropogenic factors, soil erosion, enzyme activity, cellulolytic activity, actinomycetes, small-sized fungi, spore-forming bacteria

Key findings: Cellulolytic activity is an important indicator of the intensity of destruction processes in the soil. Results showed that in individual horizons, the microbiota variations proved associated with the humus state of the studied soils.