Investigation of Some Physical Properties and Evaluation of Fractal Dimension of Primary Soil Particles in Different Uses

Despite the diversity of land use in arid and semi-arid areas of the country, land use can change the soil quality characteristics, as well as soil physical quality. The aim of this study was to investigate the effects of different land use on soil characteristics in the Baghan watershed in the southeast of Bushehr province with an area of about 929 square kilometers. That region has an important role in the production of agricultural products. From the surface soil (0-20 cm) of range, croplands and orchards, 120 composite soil samples were taken. Sampling sites were determined using the Latin hypercube technique. sand (Sa), silt (Si), clay (Cl), bulk density (ρb), porosity (F), air content (AC), effective porosity (Φeff), macro pores (MAP), mean weight (MWD), geometry mean of aggregate diameter (GMD), water aggregate stability (WSA), aggregate stability index (SI), relative water content (RWC), saturated moisture (ΘS), field capacity moisture (FC), permanent wilting point (PWP) and availaible water content (AWC) were determined by conventional methods and fractal dimension (Db) was calculated by mass-diameter method. range, crop land and orchard land uses had significant effect (P <0.01) on all studied characteristics except AC. Mean comparison showed that in range and crop land, among all studied characteristics, only PWP, FC and ΘS were significantly different. In orchard, compared to range, there is a significant increases trend in Sa, F, Φeff, MAP, MWD, GMD, WSA, SI, ،S, FC, PWP, AWC and RWC and a significant decreases trend in Si, Cl , Ρb and Db were observed. Fitting of the linear equation to the measured data showed that with decreasing the clay and silt and increasing the sand, the fractal dimension decreased. The coefficients of explanation of the linear function of the fractal dimension with the percentages of sand, silt and clay were 0.8, 0.55 and 0.82, respectively. Based on the studied characteristics, the most desirable physical quality of soil was observed in orchard land use.