Animal manure, agricultural residues, and other sources of biomass can be diverted from the waste stream and composted into valuable fertilizer. However, composting often results in substantial N loss through NH3 gas volatilization. We investigated biochar's capacity to improve NH3 -N retention during composting of poultry manure and straw. After 7 wk, total N loss from composting with unoxidized biochar was twofold and sixfold higher than N loss from composting with oxidized biochar and without biochar (307, 142, and 51 mg N g-1 N in the initial compost feedstocks, respectively). When cumulative NH3 -N loss was calculated relative to CO2 -C loss to account for differences in microbial activity, NH3 -N/CO2 -C loss from compost with oxidized biochar was 55% lower than from compost with unoxidized biochar (82% lower based on mass balance). Oxidized biochar particles removed from compost after 7 wk retained 16.0 mg N g-1 biochar, compared with only 6.1 mg N g-1 retained by unoxidized biochar, suggesting that N retention by biochar particles provides a mechanism for reduced NH3 -N loss. These data show that oxidized biochar enhanced microbial activity, doubled composting rate, and reduced NH3 -N loss compared with unoxidized biochar and that biochar's physiochemical characteristics modulate its performance in compost. In particular, the presence of oxidized surface functional groups, which can be increased artificially or through environmental weathering, appear to play an important role in key compost processes. This has implications for other natural and managed systems where pyrogenic organic matter may mediate biological activity and nutrient cycles.

中文翻译：

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用氧化生物炭堆肥造成的氨挥发

动物粪便、农业残留物和其他生物质来源可以从废物流中转移并堆肥成有价值的肥料。然而，堆肥通常会通过 NH3 气体的挥发导致大量的 N 损失。我们研究了生物炭改善家禽粪便和秸秆堆肥过程中 NH3 -N 保留的能力。7 周后，使用未氧化生物炭堆肥造成的总氮损失是使用氧化生物炭和不使用生物炭堆肥造成的 N 损失的两倍和六倍（初始堆肥原料中分别为 307、142 和 51 mg N g-1 N）。当相对于 CO2 -C 损失计算累积 NH3 -N 损失以解释微生物活性差异时，氧化生物炭堆肥的 NH3 -N/CO2 -C 损失比未氧化生物炭堆肥低 55%（基于关于质量平衡）。7 周后从堆肥中去除的氧化生物炭颗粒保留 16.0 mg N g-1 生物炭，而未氧化生物炭仅保留 6.1 mg N g-1，表明生物炭颗粒保留 N 提供了减少 NH3 -N 损失的机制。这些数据表明，与未氧化的生物炭相比，氧化的生物炭增强了微生物活性，使堆肥速率加倍，并减少了 NH3 -N 损失，并且生物炭的理化特性调节了其在堆肥中的性能。特别是，可以人工或通过环境风化增加的氧化表面官能团的存在似乎在关键堆肥过程中发挥着重要作用。这对其他自然和管理系统有影响，在这些系统中，热解有机物质可能介导生物活动和营养循环。