Fractal dimensions of soil structure and soil anti-erodibility under different land use patterns

Abstract

Soil structure fractal features and soil anti-erodibility were studied by the combinative means of field investigation and laboratory analysis under different land use patterns. The results showed that fractal dimensions of mechanical composition were greater than that of micro-aggregates, and fractal dimensions of water-stable aggregates were greater than that of dry aggregates. Five land use patterns had a high proportion of aggregates measuring >2 mm after dry sieving and <0.5 mm after wet sieving. Soil dispersion was mainly reflected in aggregates that measure between 0.05 to 0.001 mm. Soil anti-erodibility in the Chinese fir plantation and Eucalyptus plantation were higher than those of the tea plantation, loquat orchard and abandoned farmland. Stability of water-stable aggregate was highest in the Chinese fir plantation, followed by the eucalyptus and tea plantations, and it was lowest in the loquat orchards and abandoned farmland. With the exception of coarse dust, changes in the composition of other soil particles of the same size varied according to different land use patterns. Changes in the status of aggregates and the degree of aggregation were inversely related to changes in the dispersive coefficient. Water stability indices and contents of soil organic matter in the Chinese fir plantation, the eucalyptus plantation and loquat orchard were higher than those of the abandoned farmland and tea plantation. From the results, it can be concluded that land use patterns of the Chinese fir and eucalyptus plantations are a reasonable manner for the increases in soil anti-erodibility and improvements in soil structure in the study area. Key words: Soil aggregates, soil fractal feature, soil water stable index, soil organic matter, land use patterns.