Table 2
The vineyard soils from the Alcubillas site showed a heterogeneous concentration for the elemental composition (Table 2), with Si and Ca being the most abundant major elements followed by Al, influenced by the parent rock. The average soil cointents in Ca were 134.4 g·kg–1 in topsoil (Ap horizons) and 161.6 g.kg–1 in subsoil (B horizons). These values (that highlight the calcaric character of the studied soils) are higher than the global average (15 g·kg–1, Kabata Pendias 2011 and other authors); in some case the Ca content even reached values up to 412.7 g·kg–1. It is worth pointing out that there are wine areas in the world with similar contents in Ca and many of these are highly appreciated for their wines. This is the case, for example, in the Champagne and Burgundy regions in France, Tuscany in Italy, and La Rioja in Spain.
Iron (Fe) and potassium (K) are present at lower levels that Ca. Iron – the average content of which in both horizons was 32.3 g·kg–1 – is necessary for the formation of chlorophyll, the respiration process of plants and the formation of certain proteins. The value for sulfur (S) obtained in the study area is 0.6 g·kg–1, a value below the average world background level (0.70 g·kg–1, Kabata-Pendias 2011).
The variances in the Si and Ca values are very large, while Na, Mg, S, P and Mn showed low variance. These variations can be explained as being the result of soil evolution and, to a lesser extent, ploughing and agricultural practices, as reported by Mîrlean et al. (2007). Manganese (Mn) concentrations varied very little in the soils in the study area (between 0.7 and 0.6 g·kg–1).