Field research was conducted at Siedlce University of Natural Sciences and Humanities in 2019–2021. The objective was to determine the effects of bacterial formulations and cover crops on the biomass, number and species composition of dominating weeds prior to spring barley harvest. The field trial involved two factors: A – bacterial formulations: I – control, II – nitrogen-fixing bacteria ( Azospirillum lipoferum Br17, Azotobacter chroococcum), III – nitrogen-fixing bacteria ( Azospirillum lipoferum Br17, Azotobacter chroococcum) + phosphorus-solubilizing bacteria ( Bacillus megaterium var, phosphaticum, Arthrobacter agilis), IV – nitrogen-fixing bacteria ( Azotobacter chroococcum) + plant growth-promoting rhizobacteria (PGPR) ( Bacillus subtilis, Bacillus amyloliquefaciens, Pseudomonas fluorescens); B – cover crops: control without a cover crop, red clover, red clover + Italian ryegrass, Italian ryegrass. Spring barley was harvested in late July. Weed samples were collected just before harvest to determine the fresh and dry matter of weeds as well as their number and species composition. The research demonstrated conclusively that an application of bacterial products combined with cover crops contributed to a significant reduction in the weight and number of weeds including dominating species such as Chenopodium album, Sinapis arvensis, Tripleurospermum inodorum and Elymus repens. Superior weed control was achieved in spring barley grown in combination with Azotobacter chroococcum + PGPR and a mixture of red clover and Italian ryegrass as a cover crop.

The work assessed the diversity of the natural potential in communes of Szczecin Metropolitan Area with particular emphasis on the areas of natural and valuable nature, protected area, forests and green areas. Established links between natural resources of municipalities and their valorisation using the SWOT analysis method (included in development strategies) and planned development goals. The basic method of use of the natural potential of the municipality are: to improve the quality of life of residents and tourism development. The impact of the natural potential on the quality of life is noticed primarily by urban centres, where a large share of green areas is noticed. The commune with a dominant share of protected areas (include Natura 2000) draws attention to the development of tourism based on natural potential. This is particularly evident in the communities that are characterized by a favourable location in relation to watercourses and reservoirs (freshwater and marine). However, in the socio-economic development, the natural potential is used in both these directions: to improve the quality of life and the development of tourism. In local strategic documents, it can be noticed that the transport system based on bicycle, pedestrian and water routes related to the natural potential can be eff ectively used in building cooperation between the central and other municipalities associated in Szczecin Metropolitan Area.