Abstract:

Soil aggregate stability, as a key indicator of soil structure, is a product of interactions between soil environment, management practices, and land use types. Soil samples were collected from land with different vegetation in the loess hilly-gully region. The content of the soil water stable aggregate was measured by the fast wetting and slow wetting method of Le Bissonnais. The impact of land use and wetting velocity on soil aggregate stability was analyzed. The results indicated that percentage composition of water stable aggregate with a diameter larger than 0.2 mm, mean weight diameter (MWD), geometrical mean weight (GMD) from planted forest land were larger than those of the soil from orchard and farmland. Fractal dimensions of water stable aggregate size distribution of the soil from orchard and farmland were larger than those of the soil from forests, which indicated that the soil structure under forest lands had been improved. There were significant relationships between organic matters, >0.2 mm aggregate content, MWD, GMD and D. Organic matter was the main cementing and stabilizing agent of aggregate formation. Soil aggregate stability was different with measurement methods of the fast wetting and the slow wetting. The fast wetting caused greater disruption than the slow wetting, indicating that dissipations played an important role in the collapse of soil aggregates.

Key words: land-use types, soil water stable aggregate, Le Bissonnais method, loess hilly-gully region