Nitrogen and Phosphorus Content in Cereals and Dicot Grasses Leaves and Features of Their Rhizosphere Microflora in Multi-Age Fly Ash Dumps

The nitrogen (N) and phosphorus (P) content was studied in the leaves of 6 cereals and 18 nonlegume dicotyledonous grass species, as well as directly in the substrates of nonrecultivated areas of two fly ash dumps of different ages. The total quantity of microorganisms and nitrogen fixers capable of phosphate solubilization and indole-3-acetic acid (IAA) synthesis was analyzed in the rhizosphere of two pioneer (Alopecurus aequalis, Ranunculus sceleratus) and two late successional (Poa pratensis, R. auricomus) plant species. Higher N and P contents and a lower N/P ratio were found in the leaves of dicot grasses compared to cereals. The quantity of nitrogen fixers in the rhizosphere of dicots was higher, which coincided with the higher content of total nitrogen in it. The proportion of nitrogen fixers with an increased ability to solubilize phosphate and produce IAA was significantly higher in the early stages of fly ash dump overgrowth.