Abstract:

To analyze and compare the stability of soil aggregate under different land use for crops, and reveal the effect and influence of human activities and crops growth on soil quality, an experiment on farmland soil was conducted. Fractal dimension and moment method parameter were employed, and farmland soil in the hilly-gully region of loess plateau in west Shanxi province is taken as research object. Results reveal that: 1) according to the aggregate fractal dimension of surface soil, the stability of soil structure ranges in order of potato, millet, mung bean, soybean, apple, corn, sunflower and walnut from strong to weak; 2) according to the fractal dimension of water-stable soil aggregate, the stability of soil structure ranges in order of mung bean, soybean, potato, sunflower, millet, corn, apple and walnut from strong to weak. The amount of soil aggregates (0.25~3mm) of millet is the highest, followed by mung bean, soybean, potato, corn, sunflower, apple and walnut. In consideration of the composition of soil aggregates, water stable aggregates and the fractal dimension, the soil structure and stability of potato, millet, mung bean, soybean and apple are better, and that of walnut is the lowest among these eight crops. By using moment method and characteristic parameters we concluded that the value of CS of soil layer in depth 0~20cm is generally smaller than the CS in depth 20~40cm. The value of CS of walnut ground even is negative. The difference of convex peak coefficient (CE) is not obvious and are all negative. The research achievements suggest that the damage of human disturbance to the structure of surface soil is apparent and the soil structure of land use for crops is generally poor.

Key words: hilly-gully region of loess plateau, land use for crops, soil aggregate, fractal dimension, moment method