Total sulphur contents over a three-year period in different organic vineyards of Apulia region, South-Eastern Italy

Sulphur (S) is one of the most important pillars of pest control in organic viticulture. In organic vineyards, sulphur is used mainly for the control of grapevine powdery mildew. Grapevine is widely grown organically in Apulian farms. The objective of the work was to evaluate total sulphur concentrations with ICP-OES in four Apulian organic vineyard over a three-year period. Total sulphur contents were determined also in other fields such as olive groves and a pasture where no sulphur had been used. The highest values were found in the organic vineyard where the smallest quantities of sulphur were used. No relationship was found between sulphur applications and its effective accumulations. A decrease of S concentrations was observed in the vineyard where the highest quantity of sulphur was used in 2005 and 2006 growing seasons whereas an increase was observed in the field where relatively low quantities had been applied. Furthermore, total S concentrations were higher in the control fields where no sulphur-based treatments had been performed. Results obtained indicated that many factors must be taken into account while considering sulphur turnover, the most important of which are soil management, climate and crop growth pattern. A positive correlation was found between total S concentrations and organic matter contents. Our results, although confined into a relatively short period of time, underlined the urgent need for further investigations to follow sulphur long-term dynamics in the Mediterranean soils.