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（IPCC）在2019年精细化指南中确立了一套估算向矿质土壤添加生物炭（biochar）所固存碳量的方法，该方法要求热解温度（pyrolysis temperature）超过350°C，并涉及三个变量：组分中的有机碳含量（<i>F</i>_c）、100年后残留的生物炭碳比例（<i>F</i>_perm）以及生物炭质量。日本自2020年起使用IPCC默认值，在其国家温室气体清单中报告生物炭改良措施。不过，日本传统上依据日本工业标准（JIS）M 8812评估生物炭特性，该标准测量固定碳（fixed carbon，<i>FC</i>）、挥发分（volatile matter，<i>VM</i>）和灰分含量。本研究针对木质和竹制生物炭，开发了一套将JIS参数转换为IPCC变量<i>F</i>_c和<i>F</i>_perm的规程。我们建立了基于<i>VM</i>/<i>FC</i>的幂近似表达式以估算热解温度，并根据JIS值、有机碳含量（C_org，%）与<i>F</i>_perm之间的线性关系推导了转换方程。本研究提出了木质和竹制生物炭的清单国家特定值，其中<i>F</i>_c（<i>F</i>_c = C_org/100）和<i>F</i>_perm反映三种热解温度水平。该转换规程可对多种生物炭原料进行实用且经济高效的应用，为国家特定变量的开发以及更广泛地利用生物炭实现二氧化碳去除（carbon dioxide removal）提供支持。