Abstract
The growing demand for food and the environmental concerns raised by excessive chemical fertilizer use have increased interest in sustainable soil fertility management practices. Biofertilizers (BFs) contain beneficial microorganisms that improve nutrient cycling and support plant growth. Biochar (BC), a carbon (C) rich material produced from biomass pyrolysis, improves soil structure, nutrient retention, and soil health. Although both BF and BC have been extensively studied individually, few studies have examined their combined effects. This systematic review summarizes the results from 66 peer-reviewed studies published between 2015 and 2025. The studies were identified through the Web of Science Core Collection and screened following Preferred Reporting Items for Systematic Reviews and MetaAnalyses (PRISMA) guidelines. The review evaluates the combined effects of BC and BF application on soil quality, nutrient availability, crop growth, stress tolerance, and environmental emissions. It was found that the combined application of BC and BFs improved microbial activity, soil enzyme activity, nutrient uptake, crop biomass, and yield more effectively than single applications. The reported reductions in global warming potential (GWP) and greenhouse gas intensity (GHGI) also indicated their environmental benefits. However, the effectiveness of BC+BF co-application varied, depending on biochar feedstock, pyrolysis conditions, microbial strains, application methods, and soil properties. Current challenges for co-application of BC and BFs include determining optimal application rates, selecting suitable biochar materials, and the limited availability of long-term and large-scale field studies. Overall, BC and BFs co-application shows strong potential for improving agricultural sustainability and resilience. Future studies should focus on long-term field experiments across different agroecological conditions.