Restoration of degraded soils in a military-affected region in the South of Ukraine based on biologisation

Abstract Background : This study was motivated by the need to restore soils degraded by military operations, accompanied by compaction, destruction of structure and contamination with heavy metals, which reduce the productivity and ecological functioning of agroecosystems. The aim of the work was to evaluate the effectiveness of using microbial preparations and green manure crops separately and in combination to improve the condition of ordinary chernozem. Methods : The study involved a field experiment with four treatment options: control; application of the “Azogran” biological preparation; green manure with a mixture of vetch and mustard; and a combination of these, and determination of the content of heavy metals in the soil and their biological activity. Results : The study found that the combined option provided the most positive changes: density decreased from 1.52 ± 0.03 to 1.28 ± 0.02 g/cm 3 ; the measured humus-related organic matter indicator increased from 2.1 ± 0.2 to 2.8 ± 0.1%; acidity changed from 5.8 ± 0.2 to neutral 6.7 ± 0.1; and the content of available, Chirikov-extractable phosphorus and potassium, reported as P 2 O 5 and K 2 O, increased by 30.0 and 22.0%, respectively. Biological activity increased significantly: dehydrogenase activity doubled, and basal respiration exceeded the control by 62.3%. It was also found that the concentrations of mobile forms of lead, cadmium, zinc and nickel decreased by 25.0–32.0%, which was accompanied by a 2.5-fold decrease in the phytotoxicity of aqueous extracts. Conclusions : The data obtained demonstrate that the combination of the biological product with green manure resulted in synergistic improvements, simultaneously improving the physicochemical and biological properties of the soil and reducing the accumulation of metals. The practical significance of the study lies in confirming the possibility of using this approach as an affordable, environmentally safe and effective way to restore land damaged by military equipment.