Long-term effects of biochar on soil chemistry, biochemistry, and microbiota: Results from a 10-year field vineyard experiment

Application of biochar to soil has been recommended as a carbon sequestration approach that can also improve soil physical and chemical properties. The addition of biochar to soil can change the physicochemical properties of the soil, leading to a subsequent modification of the microbial community. However, the long-term implications of these changes remain insufficiently elucidated. Here, we examined soil chemical and biochemical properties of the bulk soil and employed next-generation sequencing techniques to analyze the microbiological properties of both bulk and rhizosphere soils after 10 years of biochar application. Specifically, we compared these properties between soil treated with two doses of biochar, i.e., SB and DB, and untreated soil, i.e., CK. After 10 years, biochar application increased the soil organic carbon from 12.7 g.kg−1 in CK to 17.3 and 23.1 g.kg−1, in SB and DB, respectively. Moreover, biochar application led to a slight decrease in soil bulk density, and increased the soil pH value 6.33 in CK to 7.07 in DB. Moreover, our findings revealed a distinct taxonomic signature within bacteria; however, this signature was not observed in terms of diversity. Specifically, we observed an increase in the abundance of oligotrophic bacteria compared to copiotrophic bacteria. The double dose of biochar increased the fungal species richness in the rhizosphere, particularly of Basidiomycota yeasts, from a relative abundance of 9.4 % in the CK soil to 17.0 % in the SB soil and 24.8 % in the DB soil and reduced putative plant pathogens like Phaeoacremonium and Aspergillus. Biochar amendment can significantly improve soil physical, chemical, and biological fertility on the long-term even under intensive viticulture management, with no detectable detrimental effects on microbial diversity and soil functions, and potential of soil organic carbon storage.