Biochar affects taxonomic and functional community composition of protists

Biochar-induced changes in microbial communities are exclusively derived from the studies on the soil bacterial and fungal communities, and we lack an understanding of how biochar can affect taxonomic and functional communities of protists. Here, the short-term effects of two biochars originating from rice husk and poultry litter (hereinafter referred to as RH and PL, respectively) on taxonomic and functional community compositions of protists in a rice rhizosphere were studied using high-throughput sequencing. Soil physicochemical properties were differentially affected by the RH and PL amendments. The relative abundance ofStramenopiles, mainly oomycetes (Peronosporomycetes), was increased in the RH-amended soil, which was correlated with the increased total pore volume and C/N ratio. In the PL amended soil, the relative abundances ofAmoebozoa,Alveolata, andExcavatawere increased, and those increases were correlated with the enhanced pH and nutrient conditions. Among functional groups, the relative abundance of phagotrophic protists increased by the PL amendment, while the relative abundance of plant pathogens was decreased by both the RH and PL amendments. Network analysis indicated that phagotrophs were the keystone group and were sensitive to the biochar amendments. The keystone taxa in each biochar treatment were different:Cercozoa(Rhizaria) in control,Conosa(Amoebozoa) in RH, andDiscoba(Excavata) in PL. The impact of biochar on protist communities correlated with its physicochemical properties, which depends on the source material.

Automated summary

This study found that the application of biochar to soil resulted in an increase in the relative abundance of Stramenopiles, mainly oomycetes, in the rice husk biochar amendment, while the poultry litter biochar increased the relative abundances of Amoebozoa, Alveolata, and Excavata. Additionally, among functional groups, the poultry litter biochar increased the relative abundance of phagotrophic protists, while the relative abundance of plant pathogens was decreased by both the rice husk and poultry litter biochar amendments.