Effects of Land Use Types on Soil Water-stable Aggregates in Naban River Watershed

Soil aggregates stability which could be influenced by soil environment, soil management practices and land use type can be used as an indicator of soil structural quality. The objective of this study was to evaluate the impact of conversion from natural forest to farmland(cornfield and rice-paddy field) and rubber plantation of different cultivating ages on the distribution characteristics of soil water-stable aggregates and water stability of soil aggregates in Naban river watershed. It was found that the distribution features of 5 mm and 5 ~ 2 mm soil water-stable aggregates were significantly influenced after converting natural to farming land and rubber plantation with different cultivating ages, as compared with that of natural forest, the contents of 5 mm and 5 ~ 2 mm soil water-stable aggregates lowered significantly(P 0.05) by 91.46% and 73.37% respectively under cornfields, the contents of 5 ~ 2 mm soil water-stable aggregates decreased significantly by 63.73% under rice-paddy field, the contents of 5 mm soil water-stable aggregates lowered significantly(P 0.05) by 44.66%, 65.00% and 59.47% respectively and that of 5 ~2 mm soil water-stable aggregates decreased significantly(P 0.05) by 56.21%, 43.16% and 34.34% respectively under rubber plantation converted from natural forest for one, five and ten years respectively. As compared with that of natural forest, the contents of 0.25 mm soil water-stable aggregates, MWD and GMD lowered significantly(P 0.05)under cornfields and the contents of 0.25 mm soil water-stable aggregates, MWD and GMD decreased significantly under rubber plantation which had been converted from natural forest for one, five and ten years respectively.Correlation analysis demonstrated that the contents of 0.25 mm soil water stable aggregates, MWD and GMD were extremely significantly(P 0.01) and positively related to the contents of 5 mm and 5 ~ 2 mm soil water-stable aggregates.