EN
Investigations were carried out by the means of leaching in laboratory columns. The significant correlation between pH-value of soil solution and activity of A1 wax found. Potassium fertilizers (KCl, K₂SO₄) and gypsum increased the activity of Al and acidified the soil solution. However, the intensity of decreasing of pH-value was markedly greater by the supplying of potassium chloride than of potassium sulphate. The addition of straw markedly buffered changes of pH, caused by the application of salts. The activities of straw were most effectively in the acid soil and more efficient than liming. Straw reduced the content of A1 in the soil solution too, but only in the interaction with sulphates (K₂SO₄, CaSO₄ · 2H₂O). In case of chloride-treatments, the addition of straw influenced on the increment of Al-activity. Results of investigations suggest that by using buffering system as organic matter and sulphates it is possible to prevent negatives effects of Al-influences on soil medium.