Microbial biomass C, N and water extractable carbon: impact of land use types and elevation gradient in himalayas

Abstract

Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and water extractable organic carbon (WOC) are important parameters of soil fertility and essential indicators for sustainable management of any land use types. This study was undertaken in 2B4D6-watershed of central Himalaya to examine the soils (0–30 cm depth) of different land use types i.e. agroforestry (agrisilviculture, agrihorticulture, agrihortisilviculture, agrisilvihorticulture), silvipastoral (chir pine, mixed and banz oak based silvipasture) and grasslands for MBC, MBN, microbial population and WOC along the elevation gradient ranging from 980 to 2250 m a.s.l. Watershed (2B4D6) was delineated in five elevation zones i.e. E₁ (< 1100 m), E₂ (1101–1400 m), E₃ (1401–1700 m), E₄ (1701–2000 m) and E₅ (> 2000 m). The MBC, MBN, microbial population and WOC contents varied significantly among land use types and it increased along the elevation. Significantly highest MBC and MBN (597.33 and 65.33 µg g⁻¹ dry soil) was recorded in banz oak-silvipasture and lowest in grassland (318.59 and 37.80 µg g⁻¹ dry soil), respectively. While, WOC ranged from 139.13 to 260.32 µg g⁻¹ dry soil with highest in banz oak-silvipasture. Microbial population significantly varied in land use types along elevation and had strong positive correlation with MBC, MBN and WOC. Two principal components (which explained 87.60% of total variance) were extracted from parameters of the soil. To enhance soil health and nutrient cycling, prioritize agriculture-based agroforestry systems for their higher MBC, MBN and microbial population. Adopt silvipastoral systems as effective alternatives, especially at elevations above 2000 m, where soil benefits are maximized.