Objective  The study was conducted to explore the differences of stability of paddy soil aggregates developed from different parent materials in red soil area, with a view to providing a theoretical basis for the utilization and development of soil resources in red soil area.

Method  Six kinds of paddy soils with different parent materials developed in plough layer and plough bottom were collected from red soil area. Anhydrous alcohol, 0.1 mol/L NaOH solution, 0.002% Na₂CO₃ solution and 0.1 mol/L NaCl solution were selected as dispersions, and ultrapure water was used as control. The contents of water stable aggregates were determined by wet sieve method.

Result  The contents of water stable aggregates in plough layer was significantly higher than those in plough bottom of paddy soil with the same parent material. There was a significantly positive correlation between the content of water stable aggregate and the content of soil organic matter in paddy soil. After the four dispersions infiltrated the soil, the contents of water stable aggregates were as follows: anhydrous alcohol (86.31%) > Na₂CO₃ solution (39.03%) > NaCl solution (32.49%) > NaOH solution (10.70%).

Conclusion  For paddy soil in the same soil layer (plough layer), there are significant differences in the water stability of soil aggregates of different parent material types, which rank as: quartzite weathering material > acid crystalline weathering material > lake sediment > river sediment > quaternary red clay > argillaceous weathering material. For the paddy soil developed from the same parent material, the water stability of aggregates in plough layer is significantly stronger than that in plough bottom. Strong alkali environment can significantly reduce the water stability of paddy soil.