Assessment of soil microbial and enzyme activity in the rhizosphere zone under different land use/cover of a semiarid region, India

Background: Land use/cover and management practices are widely known to influence soil organic matter (S-OM) quality and quantity. The present study investigated the effect of different land use, i.e., forests viz. mixed forest cover (MFC), Prosopis juliflora (Sw.) DC-dominated forest cover (PFC), and cultivated sites viz. agriculture field (AF), vegetable field (VF), respectively, on soil parameter, microbial activity, and enzymes involved in soil nutrient cycle in a semiarid region of India. Results: The results showed a significant reduction (P < 0.05) in soil carbon (S-C), soil nitrogen (S-N) content (similar to 30-80%) and consequently the soil microbial biomass carbon (S-MBC) (similar to 70-80%), soil basal respiration (S-BR), soil substrate-induced respiration (S-SIR), and soil enzyme activities (beta-glucosidase, acid phosphatase, and dehydrogenase) under cultivated sites in comparison with forest sites. Pearson's correlation showed that a positive correlation of S-C with S-MBC, S-BR, S-SIR (P < 0.01), and enzymatic activities (i.e., beta-glucosidase, dehydrogenase) (P < 0.05) may imply the critical role of S-C in regulating microbial and enzymatic activity. Also, a positive correlation of soil moisture with urease activity (P < 0.01) was found suggesting it as a significant abiotic factor for soil biological functions. Additionally, based on the PCA analysis, we observed the clustering of S-MBC/S-C ratio and qCO(2) nearby AF. Conclusion: Our study suggests that soil microbial parameters (S-MBC, S-BR, S-SIR, S-MBC/S-C, qCO(2)) and enzyme activity are key indicators of soil health and fertility. Land use/cover alters the S-OM content and soil microbial functions. The management strategies focusing on the conservation of natural forest and minimizing the land disturbances will be effective in preventing soil carbon flux as CO2 and maintaining the S-C stock.