Assessment of N-related microbial processes in the soil of the Polesie National Park and adjacent areas, including reclaimed land.

Soil microorganisms are essential for maintaining ecosystem functionality, particularly through their role in the nitrogen (N) biogeochemical cycle. Thus, they also contribute to greenhouse gas emissions from soils. Microorganisms are sensitive indicators of soil health, as they respond rapidly to disturbances caused by factors like unsustainable agricultural practices or industrial activities, such as mining. These bioindicators are also useful for monitoring the effectiveness of environmental remediation treatments, such as soil reclamation. The study aimed to assess microbial activity related to the N cycle in soils across various habitats (peatland, grassland, forest, and field) under conservation management within the Polesie National Park (PNP), as well as in comparable conventionally managed habitats. Additionally, the effectiveness of soil reclamation was assessed using waste from the mining industry, specifically gangue. Significant differences were observed in the assessed activities, both between habitats and their locations, i.e., within the PNP and outside of it. It was found that microbial activity was lower in soils from the PNP area. This was likely a result of more intensive fertilizer application on soils not subject to the restrictions imposed by park regulations. It should be noted that urease activity, which can contribute to the adverse phenomenon of nitrogen loss from soils when elevated, similarly to nitrous oxide (NO) emission, was lower in the soils from the park than in those located outside of it. Therefore, designating an area as a national park protects the soil environment from human pressures associated with intensive agriculture, thereby helping to maintain its homeostasis. Reclamation using gangue proved ineffective in restoring microbial activity in degraded soil to the level of cultivated soil outside the park. The assessed activities in the reclaimed soil were lower than the target levels. The results provided valuable information useful for environmental management decisions in terms of soil and air protection, as well as the use of waste for reclamation.