Szukana fraza: [Abstract = "The field experiments, provided in the years 1986\-1989 have shown, that main cause of the weak effect of reforestarion of the mine dumps was the small amount of plant available nitrogen. Additional doses of l00 kg N\/ha\/year improved the pine growth considerably and caused a very surface covering between the pine rows by grasses and herbs. The intensive water erosion did not exist any more."]
