Effect of potassium fertilization on its available and fixed content in vineyard soil

The experiment was conducted on brown forest soil in the vineyard with Sauvignon blanc variety on Kober 5BB rootstock. During a thre- year experiment (1994-1996), potassium fertilizer was added in a dose of 0 kg K2O/ha, 50 kg K2O/ha, 100 kg K2O/ha, 150 K2O/ha respectively. After the determination of soil potassium content (1870-1920 mg K2O/100 g), its available form was monitored by using two different extraction methods (AL method and 1N ammonium-acetate extraction). The amount of extracted available K was not significant between the used methods, while the effect of fertilization was visible only at 150 kg/ha potassium rate during the first year in soil layers (30-60 cm, 60-90 cm). Also, another examined soil K fraction (fixed K+) was not affected by K fertilizer application