Soil Microbial Characteristics in Sub-Tropical Agro-Ecosystems of North Western Himalaya

Eight predominant land use systems, viz. agriculture (T₁), horticulture (T₂), agrisilviculture (T₃), silvopastoral (T₄), agrihorticulture (T₅), agrihortisilviculture (T₆), forest (T₇) and grassland (T₈) of subtropical parts of Himachal Pradesh were selected along two altitudinal ranges A₁ (365–635 m amsl) and A₂ (636– 914 m amsl) to observe the variation in soil microbial activity and microbial characteristics. Agroforestry land uses and forest ecosystems displayed significantly higher microbial counts and microbial biomass carbon than agriculture and grasslands. The CO₂ evolution (soil microbial activity) was found higher in agrisilviculture, agrihortisilviculture, forest and grass-land use systems at both altitudinal ranges. Soil biological properties (microbial count, microbial biomass and microbial activity) were maximum in forest landuse system. Among the agroforestry land-use systems, agrisilviculture had significantly higher microbial counts. The maximum microbial count (164.50 × 10⁵ cfu g^–1 soil) was recorded in forest and remained statistically at par with agrisilviculture (162.34 × 10⁵ cfu g^–1 soil). Minimum microbial count (80.66 × 10⁵ cfu g^–1 soil) was observed in agriculture land use. At both the altitudinal ranges, the CO₂ evolution was highest at 48 h time interval and decreased thereafter. The metabolic quotient (qCO₂) indicated that C-use efficiency is higher in grassland use and agriculture land use systems than other studied systems.