European Journal of Sustainable Agroecosystems

Background: Biochar is a carbon-rich substance created by pyrolyzing organic biomass in an oxygen-limited environment. Recently, biochar is gaining popularity as a soil improvement tool. There is an increasing amount of literature confirming that biochar affects not only the physicochemical properties of soil but also significantly alters the taxonomic and functional structure of microbial communities that inhabit that soil with implications for nutrient cycling, greenhouse gas emissions, and resilience of ecosystems.
Objective In this review paper, we are going to summarize peer-reviewed literature about the effects of biochar on soil microbial functional diversity with focus on mechanisms, various affecting factors (soil type, feedstock, pyrolysis temperature, application ratio, and duration of the amendment), and functional consequences.
Method Literature sources: A well-structured search of Scopus, Web of Science, PubMed, and Google Scholar was completed for the publications between 2011 and 2026, with the addition of appropriate institutional and international documents. After reviewing the titles and abstracts and the eligibility of the documents, relevant 98 studies were included for thematic and comparative synthesis.
Result Key findings: The finding from meta-analysis and primary field/laboratory studies demonstrated that biochar has positive influences on the soil pH, cation exchange capacity, and the availability of labile carbon, which results in alterations in bacterial beta-diversity, the selective enrichment of oligotrophic and pH-tolerant taxa, modifications of enzyme activities (dehydrogenase, urease, phosphatase), and changes in the abundance of functional genes responsible for nitrogen fixation, nitrification, and denitrification. The impact on the alpha-diversity of bacteria differs according to studies, while mycorrhizal fungi and fungi reactions have less research done. Pyrolysis temperature and material have an interaction in terms of whether biochar delivers a boost of the fast-carbon-based microbes or supports the stabilization of microbes. Research gaps: validation in field conditions lasting over five years, application of standardized methods for functional diversity evaluations, integration of various multi-omics approaches, and investigations focusing on tropical and weathered soils.
Conclusion Conclusions: biochar is an effective but context-dependent tool of manipulating soil microbial diversity; to realize its potential in agriculture and climate action it is essential to adopt precise strategies based on practical data and numerous multi-omics studies.