EN
In the perennial field experiment the after - effect of simulated acid rainfall was determined on the magnesium level and cation equilibrum in soil and in cocksfoot-grass. The after-effect of rainfall with pH 3,2 was observed as a considerable increase of share of percentage hydrogen and a decrease of share of magnesium and calcium in the cation - exchange capacity. It was a cause of decrease of the content of available magnesium in soil and of the total magnesium in plant.