University College, Dublin, Ireland.
J Environ Qual. 2012 Jul-Aug;41(4):1203-9. doi: 10.2134/jeq2011.0119.
Biochar is the product of pyrolysis produced from feedstock of biological origin. Due to its aromatic structure and long residence time, biochar may enable long-term carbon sequestration. At the same time, biochar has the potential to improve soil fertility and reduce greenhouse gas (GHG) emissions from soils. However, the effect of biochar application on GHG fluxes from soil must be investigated before recommendations for field-scale biochar application can be made. A laboratory experiment was designed to measure carbon dioxide (CO) and nitrous oxide (NO) emissions from two Irish soils with the addition of two different biochars, along with endogeic (soil-feeding) earthworms and ammonium sulfate, to assist in the overall evaluation of biochar as a GHG-mitigation tool. A significant reduction in NO emissions was observed from both low and high organic matter soils when biochars were applied at rates of 4% (w/w). Earthworms significantly increased NO fluxes in low and high organic matter soils more than 12.6-fold and 7.8-fold, respectively. The large increase in soil NO emissions in the presence of earthworms was significantly reduced by the addition of both biochars. biochar reduced the large earthworm emissions by 91 and 95% in the low organic matter soil and by 56 and 61% in the high organic matter soil (with and without N fertilization), respectively. With peanut hull biochar, the earthworm emissions reduction was 80 and 70% in the low organic matter soil, and only 20 and 10% in the high organic matter soil (with and without N fertilization), respectively. In high organic matter soil, both biochars reduced CO efflux in the absence of earthworms. However, soil CO efflux increased when peanut hull biochar was applied in the presence of earthworms. This study demonstrated that biochar can potentially reduce earthworm-enhanced soil NO and CO emissions. Hence, biochar application combined with endogeic earthworm activity did not reveal unknown risks for GHG emissions at the pot scale, but field-scale experiments are required to confirm this.
生物炭是由生物源原料热解产生的产物。由于其芳香结构和较长的停留时间，生物炭可能实现长期碳固存。同时，生物炭具有提高土壤肥力和减少土壤温室气体（GHG）排放的潜力。然而，在推荐田间规模应用生物炭之前，必须研究生物炭应用对土壤 GHG 通量的影响。本研究设计了一个实验室实验，以测量两种爱尔兰土壤在添加两种不同生物炭、内生（土壤取食）蚯蚓和硫酸铵时的二氧化碳（CO）和氧化亚氮（NO）排放，以协助全面评估生物炭作为一种 GHG 减排工具。当以 4%（w/w）的比例添加生物炭时，两种有机质含量低和高的土壤中的 NO 排放均显著减少。蚯蚓分别使低和高有机质土壤中的 NO 通量增加了 12.6 倍和 7.8 倍。在添加生物炭的情况下，蚯蚓存在时土壤中 NO 排放的大幅增加显著减少。生物炭分别使低有机质土壤中蚯蚓的排放量减少了 91%和 95%，高有机质土壤中减少了 56%和 61%（有无氮施肥）。在使用花生壳生物炭的情况下，低有机质土壤中蚯蚓的排放量分别减少了 80%和 70%，高有机质土壤中减少了 20%和 10%（有无氮施肥）。在高有机质土壤中，两种生物炭在没有蚯蚓的情况下均降低了 CO 排放通量。然而，当花生壳生物炭在有蚯蚓的情况下应用时，土壤 CO 排放通量增加。本研究表明，生物炭可能潜在地减少蚯蚓增强的土壤 NO 和 CO 排放。因此，生物炭应用与内生蚯蚓活动结合在盆内尺度下并未显示出对 GHG 排放的未知风险，但需要田间规模实验来证实这一点。
