Abstract:Fractal dimension of soil particle size distribution (PSD) was calculated by a method on the basis of accumulative volume distribution of soil particles. Fractal properties of PSD in profiles of paddy soils sampled from Cixi City of Zhejiang Province were investigated with the new method, and rice-cultivation ages of these paddy soils were 50, 100, 500, 700, 1000 and 2000 years, respectively. Results showed that the volume fractal dimension of PSD was more reasonable and credible than the mass fractal dimension of PSD. The PSD of paddy soils cultivated for different years could be significantly fitted by the volume fractal model (p<0.01). The volume fractal dimension of soil particles was in significantly positive correlation with the volume percentage of soil clay (p<0.01), and in significantly negative correlation with the volume percentage of silt and sand (p<0.01). Compared to silt and sand, the effect of soil clay content on the volume fractal dimension of PSD was more remarkable. Cultivated age had some influence on volume fractal dimension of paddy soils and fitness of the fractal model. Variability and mean of volume fractal dimension of soil particles in profiles of paddy soils cultivated for 700 ~ 2000 years were higher, and determination coefficient of their fitting models was lower, as compared with paddy soils cultivated for 50 ~ 500 years. Cultivation age could influence fractal property of soil particles in soil profiles through changing distribution of clay content. Fractal dimension of paddy soils with the same texture increased with increasing cultivation age.