Vineyard soil characteristics related to content of transition metals in a sub-Mediterranean winegrowing region of Slovenia

Abstract

This study was conducted to obtain an overview of transition metals (Cd, Co, Cu, Mn, Mo, Pb and Zn) in the soils of the sub-Mediterranean winegrowing region in Slovenia. Twenty-four soil sampling sites (22 vineyards, 2 forests) were selected to obtain a reliable set of data and possibly find differences in metal content. The sites differ in soil properties, vineyard age, landform and soil depth. Soil depth and vineyard landform were found to have no significant influence on soil characteristics. Statistically significant differences in CEC (cmol kg − 1 ), pH and loss on ignition were found between vineyard and forest soils. Vineyard soils with average metal content of Cd (1.4 mg kg − 1 ), Co (23 mg kg − 1 ), Cu (7 mg kg − 1 ), Mn (1251 mg kg − 1 ), Mo (1.7 mg kg − 1 ), Pb (22 mg kg − 1 ) and Zn (101 mg kg − 1 ) can be classified as less polluted, even though the content levels of Cd, Co and Cu are higher than the limited values as defined by the Slovenian Directive. The contents of Cd and Co in forest soil were also higher than the limit values, which can only be explained by the parental material influence. The highest contents of Zn, Pb, Cu and Mn were detected in topsoil layers, although the differences according to soil sampling depth were insignificant. In view of vineyard landform, the significantly highest contents of Pb (26 mg kg − 1 ), Co (24 mg kg − 1 ), Mo (1.9 mg kg − 1 ), Cd (1.8 mg kg − 1 ) and Mn (1271 mg kg − 1 ), but not for Zn and Cu, were determined on planes. The content of Cu significantly increases with a vineyard's age. The study confirmed that the main source of transition metal pollutant in the region is intensive viticulture practice, especially the use of copper substances.