Effects of fluvo-aquic soil biochar on soil bacterial communities of different rice varieties in Guangdong Province

Objective  To discover the effects of biochar on soil bacterial community diversity, abundance and structure of different rice varieties, and provide a scientific basis for the application of biochar in paddy field.

Method  Experiment of split-split plot was designed in the late rice field of Fluvo-aquic soil type in Taishan Town of Jiangmen County, Guangdong Province in 2019, treatments were designed with no biochar application(CK), biochar application of 3.5 t/hm² (Tr1) and 7 t/hm² (Tr2) as the main plots, six different conventional high-quality rice varieties, including ‘Huanghuazhan’, ‘Wuchangxiangdao’, ‘Xiangyaxiangzhan’, ‘Xiangwanxian’, ‘Nongxiang 32’ and ‘Yuzhenxiang ’, were designed as the subplots in each main plots. 16S rRNA gene V3-V4 high-throughput sequencing technology analysis was conducted.

Result  Biochar Tr1 and Tr2 treatments significantly improved the bacterial community diversity of rice variety ‘Yuzhenxiang’, and biaochar Tr2 treatment significantly improved the bacterial community richness of rice variety ‘Yuzhenxiang’, and also biaochar Tr1 treatment significantly increased the bacterial community abundance of rice variety ‘Huanghuazhan’. A total of 73 phyla, 92 classes, 174 orders, 298 families, 682 genera and 456 species of bacteria were obtained, mainly including 10 main phyla of Proteobacteria, Firmicutes, Bacteroidetes, Nitrospirae, Acidobacteria, etc. Among them, the Proteobacteria are the first dominant bacteria (the proportion of relative abundance reaching 30.0%~61.1%), with γ-, δ-, and α-Proteobacteria as the dominant subgroups. Compared with CK, Proteobacteria and Bacteroidetes of some rice varieties showed a significant increase in Tr2 treatment, and Euryarchaeota increased significantly in Tr1 treatment. Biochar treatment caused changes in the structural composition of the corresponding soil bacterial community at the genus level. Soil bacterial groups with relatively low or extremely low abundance, such as Acidovorax, Sphingomonas and Pedobacter, were more sensitive and susceptible to the impact of biochar. The Tr1 treatment had an effect on the composition and distribution of soil bacteria compared with CK.

Conclusion  Biochar treatment can affect the soil bacterial community in rice field to some extent, the soil bacterial communities of rice varieties of ‘Yuzhenxiang’ and ‘Huanghuazhan’ are mostly affected by biochar. Biochar treatment increases the soil bacterial community diversity and richness of rice varieties of ‘Yuzhenxiang’ and ‘Huanghuazhan’, and the difference between biochar treatment is mainly reflected in the relative abundance of soil bacterial communities.