EN
The aim of the present investigation was to assess the influence of the accompanying grass species on the total N content in the DM of cocksfoot, timothy and perennial ryegrass. The research was conducted on the plant material collected from field experiments located in two habitats that differed in the type of soi and level of ground waters. The studied species were sown in pure sowing and in two-species mixtures (with 50% of each species). Each vegetation season, the same mineral fertilisation was applied to all the experimental objects. The plants were at the same stage of development during regrowth. Total N content was determined in the dry mass of the studied grass spccies using the Kjeldahl's method, in the year of sowing and in the following year of vegetation in the 1st, 2nd and 3rd regrowths. Cocksfoot and timothy cornpeted for nitro gen in all the regrowths, except the 1st regrowth in the dry habitat in the year sowing and both regrowths in both habitats in the year following sowing. In the year of sowing in the dry habitat neither cocksfoot nor perennial ryegrass compete for nitro gen but in the wet habitat in the year of sowing and in both habitat in the following year in all the regrowth forms, strong competition for nitrogen was found. Perennial ryegrass competed for nitrogen with timothy in all the regrowth forms except the 1st regrowth in the dry habitat and the 2nd regrowth in the wet habitat in the year of sowing.