Soil microbiome state in militarily impacted soils of Ukraine

Military operations in Ukraine are causing significant changes to the environment, with soil being one of the most vulnerable components. Explosions, the utilisation of heavy machinery, and the pollution emanating from military facilities are collectively responsible for the deterioration of the soil physical properties. This results in a reduction of soil fertility and an alteration in the soil microbiome composition. Microorganisms play a pivotal role in biogeochemical processes that affect soil quality, its regenerative capacity, and the stability of agroecosystems. The rehabilitation and restoration of ecosystems, including soils, in the aftermath of armed conflict is crucial to ensure food security and strongly depends on the soil conditions. Therefore, comprehensive study to investigate the consequences of military interventions on the microorganisms, as well as physico-chemical characteristics of soils, and their consequent influence on the ecological conditions are necessary.

We collected soil samples from a militarily disturbed area in the vicinity of the village Moshchun in the Kyiv region in May 2025. The site presents a crater left by an aerial bomb explosion in the spring of 2022. The agrochemical parameters were determined according to the standard protocols. For microbiological analysis, soil suspension was plated onto selective nutrient media. The directional coefficients microbiological processes in soil (i.e., mineralisation-immobilisation coefficients, oligotrophy, pedotrophy) were calculated according to SSU 3750-98, and microbial transformation of soil organic matter – according to Mukha V.D.

The agrochemical parameters of the soil sampled in the crater and in the area directly adjacent to it indicates degradation of the soil organic matter and a decrease in nitrogen availability. These changes indicate the areas of significant thermal and mechanical destruction. An increase in mineral nitrogen in the centre of the approximately 6 m deep crater may reflect the exposure of inorganic nitrogen from deeper parent material layers. We also observed a decrease in the contents of mobile phosphorus and potassium, as well as soil organic matter (or humus) content. These findings confirm the negative impact of the explosion on soil fertility indicators.

Samples collected from the crater and adjacent undisturbed areas exhibited pronounced shifts in the abundance of different microbial groups. In the immediate vicinity of the explosion epicentre, the abundance of oligotrophs and pedotrophs increased, whereas populations of ammonifiers, phosphate mobilisers and cellulose decomposers decreased. Directionality coefficients of microbiological processes indicate a general shift toward predominance, of mineralisation processes withn the explosion-affected zones, resulting in the loss of organic carbon and a negative humus balance. The elevated proportion of oligotrophic and pedotrophic microorganisms in the crater centre suggest depletion of readily available nutrients for the microbiota, accompanied by active uptake of mobile nutrients from deeper soil or parent materials.

We acknowledge the Ministry of Education and Science of Ukraine for the financial support of this research (Projects 0124U001049 and 0124U000960).