<p>Biochar obtained from biomass pyrolysis is increasingly being considered as a soil amendment because of its potential to enhance nutrient retention, improve soil structure, and support crop productivity under a wide range of farming conditions. However, finding good quality biochar for fertilizer application remains a challenge to the wider agricultural community. This is linked to the undefined biochar production pathways that link feedstock, process parameters, and reactor technologies for quality and quantity output. Despite extensive research on biochar production, systematic analysis linking specific reactor technologies to resultant biochar microcrystalline structure remains limited. Studies published between 2010 and 2026 were systematically examined to evaluate how different pyrolysis reactor configurations influence biochar properties relevant to fertilizer applications. These properties include surface area (&gt; 100m²/g), porosity (&gt; 50&#xa0;nm), surface homogeneity, hydrophilicity and H/C ratios (&lt; 0.7). Comparative analysis highlights that slow pyrolysis in fluidized bed reactors tends to produce biochars with higher porosity and stability, whereas microwave and plasma-assisted systems achieve enhanced surface areas but face energy and scalability challenges. Constraints, including non-uniform thermal transfer, reactor fouling, and high energy demand, continue to limit large-scale adoption. Recent work on hybrid reactor systems and data-driven optimization approaches suggests potential ways to address these challenges by improving thermal control and consistency in biochar production. Based on these findings, the review outlines practical considerations for reactor development, with particular attention to hybrid configurations, automation, and digital support tools.</p> Graphical Abstract <p></p>