Abstract

The main challenge to successful use of wheat straw as soil amendment is its slow decomposition rate as compared to other crop residues. In order to solve this problem and increase farmers’ acceptability, inoculation of straw amended soil with microbial compounds to hasten decomposition is being promoted in China. In this experiment, the effect of three types of industrially produced composite microbial system (Renyuan shengwu (RW), Taigubio (TB) and China green health (GH)) were investigated under two straw placement options (incorporation I and layered L) on wheat straw decomposition and soil biological properties. The result indicates significant differences for all the parameters measured at p ≤ 0.05. RW had highest total CO₂ emission during the incubation period (61 days). There was a correlation between total CO₂ emission and cellulase activity (R² = 0.81) and dehydrogenase activity (R² = -0.66). Placement option had effect on soil total organic carbon (TOC), microbial biomass carbon (MBC), fungi, actinomycetes and bacteria population, and cellulase activity. Both inoculation and straw returning to the soil increased TOC, micro flora and cellulase activity. The results show that direct inoculation of straw amended soil could improve straw decomposition rate and soil biological properties if suitable microbial strains are used.

Key words: Cellulase, dehydrogenase, composite microbial compound, wheat straw, straw placement.