THE INFLUENCE OF SULPHUR ON PHOSPHORUS AND POTASSIUM CONTENT IN POTATO TUBERS (SOLANUM TUBEROSUM L.)

The objective of the study was to investigate the impact of sulphur application on the content (g kg(-1)) and uptake (kg ha(-1)) of phosphorus and potassium with the yield of potato tubers. In 2004-2006, a field experiment on potato was conducted, in which S was applied in different forms (elemental and K2SO4) and doses (0, 25 and 50 kg ha(-1)). The content and uptake of P and K in the dry mass of potato tubers was significantly increased by sulphur. The application of sulphur increased the P content and uptake irrespective of the S dose, but elemental S proved more effective. The K content was the highest when sulphate was applied at 50 kg S ha(-1). The K uptake by tubers was significantly increased by both of the applied doses versus the control plots. The tuber yield depended substantially on the rate of S fertilizer. Sulphur applied as sulphate increased the content of SO4-S in the soil. The application of elemental S in a dose of 50 kg hat decreased the soil pH. The soil content of total C was dependent on each dose and form of the applied sulphur. The content of SO4-S and total C in the soil positively correlated with the P content and uptake by potato tubers. A negative correlation was found between the pH value and content and uptake of P by potato tubers. No correlation was found between K and soil parameters, but a positive correlation was found between the P and K uptake by tubers and between the P and K uptake versus tuber yield.