Estimating soil carbon sequestration with woody and bamboo biochar using the Japanese Industrial Standard (JIS) M 8812

The Intergovernmental Panel on Climate Change (IPCC) established a methodology to estimate carbon sequestered from biochar additions to mineral soils in the 2019 Refinement Guideline, requiring a pyrolysis temperature exceeding 350 °C and three variables: organic carbon content in fraction (<i>F</i>_c), fraction of biochar carbon remaining after 100 years (<i>F</i>_perm), and biochar mass. Japan has reported biochar amendments in its national greenhouse gas inventory since 2020 using default IPCC values. However, Japan has traditionally evaluated biochar properties based on Japanese Industrial Standard (JIS) M 8812, which measures fixed carbon (<i>FC</i>), volatile matter (<i>VM</i>), and ash content. This study developed a protocol to convert the JIS parameters to the IPCC variables <i>F</i>_c and <i>F</i>_perm for woody and bamboo biochar. We established a <i>VM</i>/<i>FC</i>-based power approximation expression to estimate pyrolysis temperature, and derived a conversion equation from the liner relationship between JIS values, organic carbon content (C_org, %) and <i>F</i>_perm. Inventory country-specific values for woody and bamboo biochar were proposed, with <i>F</i>_c (<i>F</i>_c = C_org/100) and <i>F</i>_perm reflecting three pyrolysis temperature levels. This conversion protocol enables practical, cost-effective application to diverse biochar feedstocks, supporting country-specific variable development and broader biochar use for carbon dioxide removal.

政府间气候变化专门委员会（Intergovernmental Panel on Climate Change，IPCC）在2019年修订指南中建立了一套估算向矿质土壤中添加生物炭所带来的固碳量的方法学，要求热解温度超过350℃，并需三个变量：组分有机碳含量（F_c）、100年后留存的生物炭碳占比（F_perm）以及生物炭质量。日本自2020年起在国家温室气体清单中采用IPCC默认值报告生物炭改良措施，但日本传统上依据日本工业标准（JIS）M 8812评估生物炭特性，该标准测定固定碳（FC）、挥发分（VM）与灰分含量。本研究针对木质与竹质生物炭，开发了将JIS参数转换为IPCC所需变量F_c和F_perm的规程。我们建立了基于VM/FC的幂近似表达式以估算热解温度，并通过JIS参数、有机碳含量（C_org，%）与F_perm之间的线性关系推导得到转换方程。研究提出了适用于木质和竹质生物炭的国家专属清单参数值，其中F_c（F_c = C_org/100）和F_perm反映了三类热解温度水平。该转换规程可实现针对多样生物炭原料的实用、低成本应用，助力国家专属变量的开发以及生物炭在二氧化碳移除领域的更广泛应用。