Next to nitrogen, phosphorus, potassium and magnesium, sulphur plays an important role in plant metabolism and is considered to be one of the most important nutrients. As sulphur deficit in Polish soils has been increasing in the last few decades, research has been carried out in order to evaluate the impact of different sulphur rates and forms on the content of macroelements (N, P, K, Ca, Mg, S, Na) and their ratios in the Mila cultivar potato tubers. A strict, three-year field experiment was set up on Haplic Luvisol with acid reaction (5.3 pHKCl), mean richness in available forms of phosphorus, potassium and magnesium but low in sulphur. The field experiments involved the sulphur application in doses of 20 and 40 kg S∙kg-1 in the form of sulphate(VI) (K2SO4 and (NH4)2SO4) as well as in elemental form (Wigor S, containing 90% of pure sulphur and 10% of bentonite). Although potatoes represent the group of crops with low sulphur requirements, the research has clearly indicated that this component has definite impact on the content of macro elements in tubers. It was found that sulphur application, irrespective of its form and rate, compared with control sample generally increased the content of nitrogen, sulphur and magnesium in potato tubers, decreasing at the same time calcium content. The effect of the form of sulphur fertilisers on the content of macroelements was not univocal. The values of all the ratios calculated (K+:Mg+2), K+:(Ca+2+Mg+2) and (K++Na+):(Ca+2+Mg+2)), except for K+:Ca+2, have generally decreased after sulphur application, which indicates positive changes in the nutritive value of potato tubers.

20.1.2015