where S is the score of the soil indicator, a is the maximum score (a = 1), x is the indicator value, x0 is the mean value of each soil indicator, and b is the value of the equation´s slope. Slope values (b) of -2.5 and 2.5 were used for a to ”more is better” or ”less is better” curve, respectively (Bastida et al., 2006). Finally, with the score of indicators and their weighting values, SQI (Eq. (2)) was calculated as follows (Masto et al., 2008):