Fractal characteristics of soil particle composition for typical types of soil profile on Loess Plateau

For searching the characteristics of the volume fractal dimension of soil particle on Loess Plateau and the relationship of volume fractal dimension and the main characteristics of soil, three typical types of soils within 0-200 cm depth were collected and tested from north to south on the Loess Plateau. They were Ust-Sandiic Entisols in Shenmu, Los-Orthic-Entisol in Yan’an and Eum-Orthic Anthrosol in Yangling respectively. Some conclusions could be drawn as follows: The volume fractal dimension of soil particle increased from north to south at the same layer and there were no significant differences among different soil layers on the Loess Plateau. The average volume fractal dimensions of soil particle of Eum-Orthic Anthrosol, Los-Orthic-Entisol, Ust-Sandiic Entisols were 2.723±0.024, 2.609±0.077, 2.589±0.025 within 0- 10 cm layer and 2.729±0.034, 2.584±0.054, 2.558±0.034 within 10-200 cm layers respectively. The volume fractal dimension of soil particle had a highly significant positive correlation with the volume percentage of soil physical clay (＜0.01 mm) and clay(＜0.002 mm) contents, a highly significant negative correlation with the volume percentage of soil silt (0.002-0.05 mm) and sand(＞0.05 mm) contents, in which there was lower correlation with the volume percentage of soil silt (0.002-0.05 mm). In addition, the contents of soil organic carbon, soil total nitrogen and the fixed ammonium had highly significant positive correlations with the volume percentage of soil physical clay contents, but a highly significant negative correlation with the volume percentage of soil sand content.