Abstract Sustainable development is imperative amid increasing energy crises and fossil fuel pollution. Crop straw, a common agricultural waste, can be converted into high‐value biochar through thermal carbonization. In this study, corn, cotton, rice, and sorghum straws were pyrolyzed at 300–500 °C, and the resulting biochars were characterized for morphology, elemental composition (C/H/N), pore distribution, and surface chemistry. Thermogravimetry indicated that 450 °C was optimal for retaining maximal residual mass. Higher temperatures increased aromatization and surface smoothness. Sorghum‐derived biochar exhibited the largest specific surface area (442.71 m 2 /g) and the highest N/C ratio (0.031), whereas rice biochar showed the lowest N/C ratio (0.019). All crop straw biochar pore sizes were predominantly 2–10 nm (average size ≈ 4 nm). Germination assays with rapeseed revealed significant enhancement (86.11%–91.67% germination) across all biochar types relative to the control. Microbial cultivation confirmed that biochar fosters a beneficial microenvironment. These findings demonstrate the agronomic potential of straw biochar and provide a reference for optimizing feedstock selection and pyrolysis parameters for plant growth and soil amendment.
Bao et al. (2025) studied this question.