Evaluation of Scoring and Weighting Methods for Soil Characteristics to Determine Soil Quality in Different Land Uses

Forests have important role for ecosystem maintenance, and deforestation is one of the factors in degradation of soil quality.  In this study, using multivariate analysis, soil quality index was evaluated in three land uses including forest, grassland, and cropland at two depths of 0-10 and 10-20 cm in Sidasht of Guilan Province, Iran. The weighted additive soil quality was calculated using two methods (1) Minimum data set (MDS1) and (2) Revised minimum data set (MDS2). Also, each feature’s variance and communality and two scoring methods, namely, linear and non-linear, were compared and evaluated. In MDS2, the effects of land use on soil quality index (SQI) indicated that the mean values calculated by the non-linear scoring method was significantly more precise than the linear one. Soil quality indices in forest and grassland had the maximum values when compared to cropland. SQIW2-MDS2-NLS had the highest sensitivity index (SI= 3.14). In MDS2, the soil properties including silt, Mean Weight Diameter, pH, CaCO3 and available phosphorus were selected. Efficiency ratio of MDS2 was 80% and in soil quality assessment, MDS2 had higher efficiency than MDS1. Soil condition and change of soil management practices were reflected in MDS2 more clearly than in MDS1. Accordingly, SQIW2-MDS2-NLS method was the best means for evaluating the effects of deforestation on soil quality in the studied area.