Linking rhizosphere soil biochemical and microbial community characteristics across different land use systems in mountainous region in Northeast India

Abstract

In Northeast India, widely practiced shifting cultivation practice created various land uses associated with altered soil biochemical and microbial attributes. The present study aimed to analyze soil biochemical and microbial characteristics in rhizosphere using Illumina paired-end sequencing in five dominant land uses (Oil Palm Plantation, OPP; Bamboo Forest, BF; Rubber Plantation, RP; Fallow Land, FL and Natural Forest, NF) of Mizoram, Northeast India. The soils of different land uses were strongly acidic (pH ranged from 4.4–5.3) in nature reflecting the dominance of acidophilic soil microbes (e.g. Acidobacteria, Proteobacteria and Verrucomicrobia) and majority of unassigned bacteria accounting >50% of all sequences. NF soil showed high organic carbon and total nitrogen (TN), however, levels of available phosphorous (Pavail), microbial biomass carbon, ammonium and nitrate nitrogen, and rates of N-mineralization (N-min) were considerably high in BF. Basal soil respiration significantly (p < .05) varied across land uses with maximum in RP and minimum in BF. Species diversity estimator showed highest bacterial diversity in BF (pH 5.3) and lowest in FL (pH 4.4). Acidobacteria were dominant in NF which declined with land use changes due to increase in soil pH. Soil pH was the strongest predictor variable explaining 96% variability of microbial diversity (R2-predicted, 78%), however, it explained 99% variability (R2-predicted, 99%) in combination with Pavail and TN. High N-min rate in BF soil was corresponded with maximum abundance of Nitrospirae. The study indicated that the changing land use patterns in this region are intertwined with changing soil biochemical and bacterial community structure.