Effect of Forest Plantations on Water Stable Aggregates of Soil

An investigation was conducted in 1967 to evaluate the effect of teak (Tectona grandis), sal (Shorca robusta), chir (Pinus roxburghii) and khair (Acacia catechu) plantations on water stable aggregates of the soil in the New Forest area of the Forest Research Institute, Dehradun. The results reveal highest total water stable aggregates in the surface soil under teak, in 8–23 cm layer under sal and chir plantations and in 23–46 cm layer under khair plantation with a decreasing trend down the profile. In general, the largest sized aggregates are more dominant in the surface layer under sal, teak and chir plantations and in 23–46 cm layer under khair plantation, while the proportion of smaller sized aggregates is greater in the lower depths. The large sized water stable aggregates showed a highly significant positive correlation with the organic matter content in the surface soil, while the small sized aggregates showed positive correlation with clay content in the subsoil. No significant positive correlation was observed with organic matter under khair and with clay under chir. Exchangeable calcium also appeared to contribute to the development of water stable aggregates in the top soil excepting under khair.