Study on soils under shifting cultivation and other land use categories in Chittagong Hill Tracts, Bangladesh

摘要

Soil samples were collected and analyzed from 25 sites of three hilly regions (Rangamati,Banderban and Khagrachari) for an understanding of the impact of denudation and land use on soils in Chittagong Hill Tracts,Bangladesh.There were natural forests,bushy land,slashed sites,slashed and burnt sites,and the sites prepared for shifting cultivation,one year after shifting cultivation and two years after shifting cultivation.The soils were generally yellowish brown to reddish brown,sandy to sandy clay loam,strongly acid,and well to excessively drained on steep slopes with considerable variation among the sites and land use categories.Bulk density was the highest in sites of one year after shifting cultivation (1.52 g·cm-3) and the lowest in foreted sites (1.38 g·cm-3).Water holding capacities were,however,statistically similar in all sites.Organic carbon varied from 0.54％ (slashed and burnt sites) to 1.55％ (forested sites) and total N ranged from 0.05％ (shifting cultivation for one year) to 0.13％ (forested sites).Available phosphorus (Bray & Kurtz-2 P) was the maximum in forested sites (12.32 mg·kg-1),and it did not differ significantly in other sites.Contents of available Ca,Mg and K were also higher in the bushy lands and forested sites than cleared and shifting cultivated sites.