Soil Characteristics and Its Dynamic Variation in a Small Catchment on the Loess Plateau of China

摘要

In this paper, taking Zhifanggou small catchment, which have been integrated controlled for more than 20 years in the typical hilly-gullied Loess Plateau, as research region, selecting 20 plots of different landuse types in the whole catchment in 1999, soil anti-scourability, stable infiltration rate, soil aggregate stability, saturated soil cohesion and soil organic matter content in these plots were measured. The experiment results showed that there had significant difference of these soil characteristics in different landuse types. Shrubland had the largest mean weight diameter (MWD) of soil aggregate stability and the strongest soil anti-scourability. The anti-scourability of shrub land and natural grassland was about 70-90 times of cropland. The content of O.M in cropland and planted grassland was about 1/2-1/3 of other landuse types. The value of stable soil infiltration rate and saturated soil cohesion was the highest in natural grassland. As a whole, the measuring values of these soil characteristics in woodland with acacia, shrubland with Caragana and natural grassland were much more higher than that in planted grassland and cropland. The variation of these characteristics in soil profile (0cm-50cm) was also significant. Generally speaking, the value of soil anti-scourability, stable infiltration rate, soil aggregate stability and soil organic matter content were all decreased clearly from upper to lower position in soil profile. The decreasing extent was reduced with the soil layer becoming deeper. According to the area of different landuse types in the catchment and its change in history, by spatial and temporal up scaling, the dynamics of these soil characteristics in the catchment after years' control measurement was analyzed. All these results provided valuable basic data for soil erosion modeling and laid foundation for qualitative assessing the soil quality and ecosystem health situation in the catchment with long term controlled measurement.