Soil Quality Dynamics across Diverse Land-Use Types in the Northwestern Himalayan Mountain Ecosystem

Across the globe, soil quality is significantly impacted by changes in land use that convert natural ecosystems into managed ones, profoundly affecting the physical, chemical, and biological characteristics of soils. The present study evaluated soil quality across four land-use systems (forest, cultivated, pasture, and scrub) and at two altitudinal ranges, viz., 651–1800 m (mid-hill region) and 1801–2200 m (high hill region) in the Mandi district of Himachal Pradesh, located in the northwestern Himalayas. Representative soil samples (0–15 cm depth) from each land-use system were collected and analysed to assess a range of physical, chemical, and biological characteristics. To calculate the soil quality index (SQI), a total of 23 soil characteristics were initially measured and reduced into a minimum data set via principal component analysis. The SQI across different land-use types ranged from medium (0.58) to high category (0.98) with the higher values observed in Forests and Pastures. Soil attributes like bulk density (BD), particle density (PD), pH, EC, Cd, Cr, Pb, and viable actinomycetes count decline with altitude, while porosity, maximum water-holding capacity, SOC, N, P, K, Ca, Mg, S, Cu, Fe, Mn, Zn, and viable fungal and actinomycetes counts increase with altitude. Overall, the study emphasizes that land use and altitude significantly influence soil quality in the northwestern Himalayas, underscoring the significance of sustainable land management techniques to maintain and improve soil quality in a variety of landscapes.