The presented study verified the possibility of using proteomics as a tool for investigating poplars growing on obviously separate plots. The examination covered poplars planted on grassland irrigated for 40 years with potato industry wastewater and in a plot appropriate for poplar planting, spaced at a distance of 67 km from each other (hereinafter referred to as forest). The work aimed to compare the obtained proteomic results with data on biometric and biochemical parameters and mineral composition as well as to assess, at a molecular level, the usefulness of grasslands for planting. Proteome analysis showed that most of the stress-related proteins detected were less abundant on the irrigated grassland, confirming the viability of its revegetation with poplars. Proteomic data corresponded well with the other results, highlighting the probable reason for the proteome changes; i.e. deficiency of phosphate ions detected in the forest area. Moreover, proteome analysis revealed biotic stress symptoms in plants growing on the grassland, which were also well explained by other data but would not have been detected without performing the proteomic analysis. Therefore, environmental plant proteomics is a useful and valuable tool during field studies, even when samples are taken from plots some distance apart.