Soil is a unique laboratory of transformations and energy flow, and in particular of biological sorption and synthesis of mineral components that can originate from various sources. The introduction of biomass or sewage into soil contributes to its nutrient enrichment. This can lead to periodical excess of these elements in soil and cause their migration from the soil system to underground waters, and eventually to open waters. Grass communities belong to a group of plants that make excellent use of nutrients present in soil and perform a very important role in additional purification of sewage after its mechanical purification. Grasses demonstrate resistance to the presence of large quantities of harmful compounds in sewage; they accumulate and neutralise them physiologically, thus preventing their dissemination. The aim of this paper was to evaluate content of some macro- and microelements as well as heavy metals in chosen grass species irrigated with purified sewage. In 1997- -2000, research was conducted near the Hajdów Sewage Works, using purified sewage for irrigation of grass communities. Three rates of irrigation (a – control without irrigation; b – irrigation in quantity 600 mm and c – irrigation in quantity 1200 mm) as well as two grass mixtures were tested. Content of basic macroelements (N, P, K, Ca, Mg), microelements (Cu, Zn, Mn) as well as heavy metals (Cd, Pb) in dominant grass species (Alopecurus pratensis, Phalaris arundinacea, Festuca arundinacea, Festuca pratensis and Phleum pratense) were determined. The content of the analyzed components in biomass was varied and depended on the grass species in the analyzing mixtures as well as on the applied rates of irrigation. Festuca pratensis and Festuca arundinacea were characterized by the largest capacity to take up calcium (Ca) and magnesium (Mg), Phalaris arundinacea – phosphorus (P) and zinc (Zn), while Alopecurus pratensis – cadmium (Cd) and lead (Pb). Biomass of Alopecurus pratensis was characterized by the lowest content of most of the elements, especially nitrogen, phosphorus, calcium and magnesium. The applied irrigation, especially the 1200 mm rate significantly increased potassium content and decreased manganese content in biomass of the analyzed grass species. The most useful grass species used to establish meadows irrigated with sewage are Phalaris arundinacea, Festuca arundinacea and Festuca pratensis.
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