Land Use Effects on Soil Biological Properties in the Hill Ecosystems of Assam, Eastern Himalayan Region of India

This study investigates the impact of land-use changes on soil microbial properties in the hilly terrain of Karbi Anglong district of Assam, Eastern Himalayan region, India. Specifically, it examines the effects of converting natural forest into various agricultural systems, including jhum cultivation, rubber plantations, rice/maize croplands, home gardens, and bamboo plantations. Forest soils consistently exhibited the highest MBC, MBN, and DHA levels in all three soil depths (0–15 cm, 15–30 cm, and 30–50 cm), followed by home gardens, while rice/maize croplands recorded the lowest values. Conversion of natural forest into other land uses led to a substantial reduction in surface soil MBC (up to 64.59%) and MBN (up to 38.62%), indicating degradation of soil biological quality. Forest and home garden systems, with richer vegetation and organic inputs, promoted higher microbial activity and nutrient cycling, while cultivated lands and monoculture plantations showed reduced microbial indicators. The decline in microbial attributes with increasing soil depth further highlights the influence of organic carbon availability. Overall, the study emphasizes the sensitivity of microbial indicators to land-use changes and their potential as early markers of soil health and fertility.