[Fractal features of soil particle size distribution in degraded sandy grassland during reclamation and enclosure].

Based on the analysis of 42 soil samples from the grassland reclaimed and enclosed different years, this paper studied the fractal features of soil particle size distribution and the relationships between fractal features and soil properties. The results showed that the fractal dimension of soil particle size distribution in 0 approximately 30 cm soil layer ranged from 2.378 in reclaimed land to 2.588 in non-grazed enclosure, while that in 0 approximately 15 cm soil layer decreased from 2.441 in grazed grassland to 2.387 after 20 years of reclamation, and increased to 2.588 after 11 years of enclosure. No significant changes were found in fractal dimension in 15 approximately 30 cm soil layer between reclamation and enclosure. Statistic analysis indicated that the fractal dimension could objectively reflect soil texture, mainly the content of clay, and then silt content. There existed a remarkable quantitative correlation between fractal dimension and soil physical, chemical and biological properties, which meant that the fractal dimension could be used as a comprehensive and quantitative index in evaluating soil properties and grassland degradation degree.