The effect of compost, biochar and bio-inoculant on enzymatic activity and some soil microbial indices

Application of biochar and compost with bio-inoculants can improve the microbiological properties of the soil. In order to investigate the effect of apple pruning wastes biochar, compost application and bio-inoculants on some biological properties of soil, a pot experiment was performed as a factorial in a completely randomized design with 2 factors: (1) organic resources (control (without organic resources), biochar and compost) and (2) bio-inoculants (control (without bio-inoculants), plant growth-promoting bacteria (Pseudomonace fluorescens, Stenotrophomonas putida, Pseudomonace aeruginose), arbuscular mycorrhizal fungus (Glomus versiform, Glomus fasciculatum ,Glomus intraradices) and endophytic fungus (Priformosphora indica) under greenhouse conditions with three replications. At the end of the corn growth period (65 days), some microbiological properties such as bacterial respiration (BR), substrate-induced respiration (SIR), microbial biomass carbon (MBC), microbial population, carbon availability index (CAI), phosphatase and urease enzymes activity were measured in soil. The results showed that the addition of organic resources and microbial inoculation to the soil caused a significant increase in biological parameters compared to treatments without organic matter and microbial inoculation. The highest levels of BR, SIR, CAI and microbial population were observed in compost- plant growth-promoting bacteria treatments, which increased by 76.2, 33.3, 77.4 and 85.8%, respectively, compared to the control treatment (without organic matter and bio-inoculants). Addition of compost and biochar significantly increased the MBC and the urease activity compared to the control treatment (no organic resources). Simultaneous application of organic and biological treatments also increased the activity of acid and alkaline phosphatase compared to the control treatment. Generally, the application of organic matter and microbial inoculation improves the soil biological properties.