Critical comparison of the impact of biochar and wood ash on soil organic matter cycling and grassland productivity
Critical comparison of the impact of biochar and wood ash on soil organic matter cycling and grassland productivity
复制标题
DOI：
10.1016/j.soilbio.2017.03.012
复制
发表时间：
2017-07
影响因子：
9.7
通讯作者：
Eleanor Y. Reed;D. Chadwick;P. Hill;Davey L. Jones
中科院分区：
文献类型：
--
作者：
Eleanor Y. Reed;D. Chadwick;P. Hill;Davey L. Jones
木材是全球最重要的可再生能源来源，根据能源生产机制，可能会产生具有截然不同特性的副产品（即焚烧产生的木灰 (WA) 和热解产生的生物炭 (BC)）。这些通常应用于土地，但缺乏对其对土壤质量和碳 (C) 循环影响的关键比较。为了解决这个问题，我们从相同的混合硬木原料中生成了生物炭（450°C）和木灰（870°C），并在实验室和田间条件下以相当的速率将其添加到农业草地中（BC 和 WA 分别为 10 t ha−1 和 571 kg ha−1）。我们假设，碱性、营养丰富的木灰会刺激微生物活动，导致土壤有机质（SOM）流失，而难以抵抗微生物侵袭的生物炭会促进原生SOM的稳定。对土壤微生物群落和土壤碳氮循环的影响在一年内确定。总体而言，生物炭通过提高养分利用率（磷和钾）、保湿性和增加土壤碳含量来改善土壤质量。然而，它也与地下二氧化碳损失的增加有关。由于植物生产力未受影响并且生物炭与14 C标记的SOM的实验室培养没有显示引发的迹象，因此我们推断该CO 2 源自生物炭本身。生物炭对土壤氮循环、微生物生物量和群落结构缺乏影响也支持了这一点。在田间条件下，木灰对土壤质量或植被质量（产量和叶面养分含量）几乎没有影响，但在实验室和田间条件下确实会引起负 SOM 启动。我们的结论是，当以现场相关速率应用时，两种修正都不会对本地 SOM 循环产生不利影响。虽然木灰可以促进天然 SOM 的保留，但生物炭由于其固有的顽抗特性，可能是提高 SOM 水平的更好策略，然而，与焚烧相比，这需要抵消热解产生的能量减少。
Wood represents the single most important source of renewable energy worldwide and depending on the mechanism of energy production can lead to the production of by-products with vastly different properties (i.e. wood ash (WA) from incineration and biochar (BC) from pyrolysis). These are typically applied to land, however, a critical comparison of their impact on soil quality and carbon (C) cycling is lacking. To address this, we generated biochar (450 °C) and wood ash (870 °C) from the same mixed hardwood feedstock and added it to an agricultural grassland at comparable rates under both laboratory and field conditions (10 t ha−1and 571 kg ha−1for BC and WA, respectively). We hypothesized that alkaline, nutrient-rich wood ash would stimulate microbial activity, resulting in the loss of soil organic matter (SOM), while biochar which is recalcitrant to microbial attack would promote the stabilization of native SOM. The effects on the soil microbial community and soil C and N cycling were determined over 1 year. Overall, biochar promoted soil quality by enhancing nutrient availability (P and K), moisture retention and increasing soil C content. However, it was also associated with an increase in below-ground CO2loss. As plant productivity was unaffected and laboratory incubations of biochar with14C-labelled SOM showed no indication of priming, we deduce that this CO2originates from the biochar itself. This is supported by the lack of effect of biochar on soil N cycling, microbial biomass and community structure. Wood ash had almost no effect on either soil quality or vegetation quality (yield and foliar nutrient content) under field conditions but did induce negative SOM priming under both laboratory and field conditions. We conclude that when applied at field-relevant rates, neither amendment had a detrimental effect on native SOM cycling. While wood ash promotes the retention of native SOM, biochar may be a better strategy for enhancing SOM levels because of its intrinsic recalcitrant character, however, this needs to be offset against the reduced amount of energy derived from pyrolysis in comparison to incineration.