The study took place between 2012 and 2014 in Falenty near Warsaw, Poland, as part of a long-term scientific experi-ment (first began in 1987) using the randomized block method. All blocks were irrigated until 2008. In 2009 each block was divided into two areas: irrigated and non-irrigated. The study involved four levels of inorganic nitrogen fertilizer and two levels of mixed inorganic and organic fertilizer in the form of fermented cattle urine. The soil in all experimental plots was characterized by low levels of zinc, ranging from 7.6 to 16.7 mg Zn∙kg–1 dry matter. Much lower Zn content in both soil layers of all irrigated plots was associated with increased yields on these plots, regardless of the level and form of ferti-lizer. The content of Zn in soil and sward in 2014 year was significantly lower compared in 2012. Inadequate levels of zinc for ruminant nutrition were observed in the sward from all plots (15.4–28.8 mg∙kg–1 dry matter). The higher content of zinc was found in sward harvested from the plot, which was not fertilized with phosphorus. The long-term inorganic and fer-mented urine fertilization resulted in very low zinc content in the soil and meadow sward.

Permanent grasslands are the most environment-friendly way of using agricultural lands. Apart from producing fodder, grasslands play many other important non-productive functions. Biodiversity is the key factor decisive for their high natural and productive values. Grasslands play an important role in water retention. Not all types of grasslands may be used agriculturally. Out of 16 types of habitats, 10 may be used for production, the others are biologically valuable. The surface area of permanent grasslands in Poland has markedly decreased during the last decade. Now, they constitute slightly more than 20% of agricultural lands occupying 3127.8 thous. ha (in 2019) including 2764 thous. ha of meadows and 363.8 thous. ha of pastures.

In greenhouse experiments the susceptibility of meadow fescue, perennial ryegrass and Italian ryegrass to Fusarium avenaceum, F. cu/mor um and F. grami num infection was studied. Various responses to Fusarium spp. infection were observed among the tested grass species and their cult i vars. Meadow fescue was the most susceptible to all the Fusarium isolates used. F. avenaceum isolates also strongly reduced perennial ryegrass emergence. In the experiments with Italian ryegrass the number of seedlings having survived the artificial infection of seeds with Fusarium spp. was significantly larger for Atos, Gran, Mitos and Polus cultivars than for Kroto, Lotos and Tur. All of the studied grasses were more susceptible to the strongly pathogenic F. avenaceum isolates than to F. culmorum and F. graminum isolates, having moderate pathogenicity.