Short-term effects of biochar and Bacillus pumilus TUAT-1 on the growth of forage rice and its associated soil microbial community and soil properties

Abstract

The synergistic effects of biochar (BC) and plant growth-promoting bacteria inoculant on crop growth and microbial communities’ composition in the rhizosphere and endorhizosphere (roots) of forage rice were examined under a short-term greenhouse condition. We performed in-pot experiments to evaluate the effects of BC and Bacillus pumilus strain TUAT-1 inoculant (Bio), both alone and in combination (BB), on the growth and microbial community of rhizosphere and roots in forage rice at 2 and 5 weeks after transplantation. At both growth stages, rice growth was improved by either BC or Bio alone. TUAT-1 was readily detected in rhizosphere with greater abundance following BB treatment than after Bio treatment alone. The bacterial communities of the rhizosphere, non-rhizosphere soil (un-planted bulk), and endorhizosphere of roots were determined using next-generation sequencing. Compared with the microbial community and diversity in the rhizosphere and endorhizosphere of roots, BC had greater effects on rhizosphere than on endorhizosphere, whereas Bio more effectively altered the microbial communities of the endorhizosphere layer of roots. Soil properties (pH and total N, exchangeable NH₄-N, and K levels) were improved by either BC or Bio alone, suggesting that the changes of soil microbial communities might occur directly or indirectly as an effect of the alteration of soil physico-chemical properties. Overall, the result from this study suggests that biochar amendment and TUAT-1 inoculant have the potential to enhance growth and nutrient uptake in forage rice, and they depend on soil physico-chemical properties and the alteration of native microbial communities’ composition.