Integrative Review of Biochar in Semi-Arid Agroecosystems: Global Trends, Potential Feedstocks, Crop-Soil Interactions, and Carbon Lability

This integrative review evaluates the current state and evolution of biochar research in arid and semi-arid agroecosystems by integrating scientometric analysis with a critical narrative synthesis. Specifically, it examines publication trends, collaboration networks, and thematic evolution while assessing the relationships among feedstock types, pyrolysis conditions, biochar properties, soil-crop interactions, labile carbon fractions, microbial processes, and practical applicability under water-limited conditions. The scientometric component uses the Web of Science Core Collection for the 2010–2025 period and applies co-occurrence, co-authorship, co-citation, bibliographic coupling, and thematic mapping to characterize the intellectual structure of the field. The narrative synthesis incorporates additional classical and recent studies to interpret mechanisms and context-dependent responses. Scientific production increased markedly over the study period, accompanied by an increasingly interconnected and multipolar research network. Research trends shifted from descriptive studies focused on feedstock characterization toward applied approaches involving soil fertility, carbon sequestration, nutrient cycling, and crop performance. Evidence indicates that biochar can improve soil functionality in semi-arid agroecosystems, particularly where low organic matter, coarse texture, acidity, or water limitation constrain plant growth; however, the magnitude and persistence of these effects depend on feedstock, pyrolysis temperature, soil properties, application rate, climate, and duration. Biochar represents a promising but context-dependent strategy for improving water retention, nutrient availability, soil structure, carbon stabilization, and biological functioning in dryland agriculture. Remaining gaps include long-term field performance, methodological standardization, carbon-balance assessment during pyrolysis, and biochar-soil-microbiome interactions under realistic semi-arid conditions.