Soil Quality Indicators and Soil Fertility of the Toposequence as Influenced by Land Use of Slope Complex Soil in the Northern Thailand

The decrease in soil fertility and increase of degradation in slope complex soil, which is evident in the mountainous areas of Northern Thailand is often represented as a result of human pressure e.g. clearing land for agricultural practices, deforestation by people, exploitation of marginal soils under inadequate soil management practice. The objective of this research was to evaluate the changes in soil chemicals and physical properties, and to examine the sensitivity of different soil quality indicators to detect changes due to different soil management under various land used located on slope complex soil in Northern Thailand. The study was carried out in the Khun Samun Watershed, which in Nan Province of Northern Thailand. The land characteristics are varied according to the position on the landscape. Five main landscape types are: undisturbed forest, secondary forest, mixed crop, fruit tree crop summit follow, Mid slope and foot slope, which are situated from 300 to 600 m, are compared to the mean soil's chemical, physical and organic ratios. Composite soil samples were collected from each land use pattern. Samples were taken at three dept