Fractal dimension of soil particle-size distribution characteristics in dry valley of upper Minjiang river

Fractal is one of the impersonality characteristics of soils. In order to study correlation of fractal dimension with soil properties and related affecting factors, the fractal dimensions of particle-size (Ds) for 161 surface (0-20 cm) soil samples under different land use patterns collected from the dry valley of upper Minjiang River were calculated by the equation of volume fractal dimension. The spatial distribution of the Ds values as well as the correlations between Ds and volumetric contents of particle size, organic matter and soil nutrients were analyzed. Ds can be used as an important parameter for characterizing the soil structures and properties. The research showed that: soil particle size distribution had different fractal characteristics under different land use patterns, its fractal dimensions were between 2.5421 to 2.6691, where silty loam > loam> sandy loam, and Ds values of farmland were bigger than the woodland. Ds had a highly significant positive correlation with the volume percentage of soil clay (<0.002 mm) and silt (0.002-0.05 mm), as well as the total potassium contents, whereas a highly significant negative correlation with the volume percentage of soil sand (>0.05 mm) contents. But the correlations of Ds with the contents of soil organic matter, soil total nitrogen, total phosphorus, available phosphorus and potassium were not significant. The result can provide a theoretical guidance for vegetation restoration and land use development.