Biochar Supplementation of Recycled Manure Solids: Impact on their characteristics and GHG Emissions during storage

Recycled manure solids (RMS) are increasingly adopted in dairy farming for their economic ad-vantages and their role in improving nutrient recycling and waste management; however, con-cerns regarding greenhouse gas (GHG) emissions during storage persist. This study assessed the effects of biochar supplementation at 2.5% (2.5B) and 10% (10B), compared to untreated RMS (C-) and acidified RMS (C+), on GHG emissions, measured continuously and intermittently, and RMS characteristics during one-month storage period. Results showed that addiction of biochar in-creased micronutrient and heavy metal concentration (with the exception of molybdenum (Mo)), as well as potassium (K) and magnesium (Mg) content by the end of the 1-month period. Howev-er, it decreased sodium (Na), phosphorus (P) and total organic carbon (TOC) content. Among treatments, 10B consistently demonstrated the greatest reductions in emissions with a decrease, relative to C- treatment, of 32% for carbon dioxide (CO₂), 47% for nitrous ocide (N₂O) and 32% regarding the global warming potential (GWP). Cumulative methane (CH4) emissions did not show significant differences. Continuous monitoring captured transient emission peaks, highlight-ing the importance of high-resolution assessments. Despite the emissions generated during biochar production, its application in RMS bedding systems offsets these environmental costs by mitigat-ing GHG emissions and increasing nutrient content. These findings highlight the potential of bio-char application as a sustainable manure management strategy. Future research should focus on long-term field trials and optimizing biochar production to maximize environmental benefits and cost-effectiveness in dairy farming.

循环粪肥固体（Recycled Manure Solids, RMS）凭借其经济优势以及在促进养分循环与废物管理方面的作用，正日益在奶牛养殖业中得到推广应用；然而，其储存过程中产生的温室气体（Greenhouse Gas, GHG）排放问题仍引发诸多担忧。本研究以未处理RMS（C-）与酸化RMS（C+）为对照，评估了2.5%（2.5B）与10%（10B）剂量的生物炭（biochar）添加对为期1个月储存周期内的温室气体排放（采用连续与间歇监测方式）以及RMS特性的影响。结果显示，至1个月储存周期结束时，添加生物炭可提升微量营养素与重金属的浓度（钼（Molybdenum, Mo）除外），同时提高钾（Potassium, K）与镁（Magnesium, Mg）的含量；但会降低钠（Sodium, Na）、磷（Phosphorus, P）与总有机碳（Total Organic Carbon, TOC）的含量。在所有处理组中，10B组始终表现出最优的减排效果：相较于C-组，其二氧化碳（Carbon Dioxide, CO₂）排放降低32%，一氧化二氮（Nitrous Oxide, N₂O）排放降低47%，全球变暖潜能（Global Warming Potential, GWP）下降32%。累积甲烷（Methane, CH4）排放则未呈现显著差异。连续监测成功捕捉到了瞬时排放峰值，凸显了高分辨率排放评估的重要性。尽管生物炭的生产过程本身会产生排放，但将其应用于RMS垫料系统，可通过削减温室气体排放与提升养分含量，抵消生产环节的环境成本。本研究结果彰显了生物炭应用作为可持续粪肥管理策略的潜力。未来研究应聚焦于长期田间试验，以及优化生物炭生产工艺，以最大化奶牛养殖业中的环境效益与成本效益。