Soil Physical Quality Indicators and Refinement of the Evaluation Method through the Srelative

Abstract

This study aimed to verify the efficiency of indicators of measure of physical attributes' alterations and to refine the S relative determination method in order to increase its sensitivity to soil physical alterations. Soils under Ficus carica L. cultivation (with 0, 20, 40 and 60% of liquid bovine biofertilizer in the irrigation depth) and under forest were used. Parameters evaluated included soil granulometry, soil bulk and particle density, soil water retention curve (SWRC), porosity and the indices S and S relative . The experimental design was completely randomized with four replicates. For S relative refinement, with the SWRC containing only textural porosity, the soil was dispersed in water and with the addition of 1 N sodium hydroxide (with and without removal of sodium through washing). An ANOVA was performed for 0, 20, 40 and 60% of biofertilizer in 0-10, 10-20 and 20-30 layers; Dunnett test was used to compare the mean values of S-index and S relative -index. With respect to four methods to obtain the S relative -index the means were compared by Tukey test. Tests of line parallelism and intercept were performed for the regressions between each of the soil physical variables and S relative -index obtained. It was found that S and S relative indices were sensitive to soil physical alterations caused by the application of the biofertilizer; Srelative-index was sensitive to variation in soil bulk density and total porosity and the S relative -index obtained from the method of soil dispersion in water is more sensitive to soil physical alterations in comparison to S relative -index obtained through ADFE.