Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China.
Sichuan Academy of Chinese Medicine Sciences, Chengdu 610041, China.
Sci Total Environ. 2019 Feb 10;650(Pt 2):1988-1995. doi: 10.1016/j.scitotenv.2018.09.356. Epub 2018 Oct 1.
Although biochar amendment to soil has achieved widely recognized benefits such as plant growth improvement and carbon sequestration, what impact it would have on soil carbon cycling, especially on the behavior of the active dissolved organic matter (DOM), is still unclear. This study evaluated biochar's effects on soil properties and the characteristics of DOM exporting from a cropland Entisol. The soil is the major arable land resource in the upper reaches of the Yangtze River, China and noted for its low soil organic matter and prevalence of preferential flow. Surface runoff, soil pore water and leachate were collected from the field upon a series of natural rainfall. Concentration of dissolved organic carbon (DOC) of soil pore water was found to respond strongly toward the rainfalls. Biochar application led to relatively higher DOC levels within the soil (p > 0.05). Despite apparent increase of DOC and EEM intensities for the freshly-amended soil, PARAFAC analyses indicated no changes in DOM's fluorophore compositions after two years of ageing. The identified DOM components (C1 and C2) showed similar dynamics with the DOCs in responding to the rainfalls. On the other hand, total flux of DOM leaching from biochar-amended plots during three monitored storms was on average 59% higher than the control (p > 0.05), whereas DOM export via surface runoff was slightly diminished. Noticeably, biochar amendment had caused a significant increase of >1000 μm macropores and thus the enhanced infiltration of soil water. Such changes led to increased flow discharge, which in turn resulted in elevated leaching of organic carbon during rainfalls. The results therefore implies that changes of soil structure and hydraulic properties that will take place after biochar application merits attention as they may play a continuous role in influencing the transport of DOM and possibly other solutes via runoff processes.
尽管生物炭改良土壤已经取得了广泛认可的益处，如促进植物生长和碳固存，但它对土壤碳循环的影响，特别是对活性溶解有机物质（DOM）的行为的影响，仍然不清楚。本研究评估了生物炭对农田土壤性质和 DOM 释放特征的影响。该土壤是中国长江上游主要的耕地资源，其特点是土壤有机质含量低，优先流普遍存在。在一系列自然降雨过程中，从田间采集地表径流、土壤孔隙水和淋出液。土壤孔隙水中溶解有机碳（DOC）的浓度对降雨反应强烈。生物炭的应用导致土壤中相对较高的 DOC 水平（p > 0.05）。尽管新添加的土壤中 DOC 和 EEM 强度明显增加，但 PARAFAC 分析表明，经过两年老化后，DOM 的荧光团组成没有变化。鉴定出的 DOM 成分（C1 和 C2）在响应降雨方面与 DOCs 表现出相似的动态。另一方面，在三个监测到的暴雨期间，从生物炭添加处理区淋洗的 DOM 总通量平均比对照区高 59%（p > 0.05），而通过地表径流的 DOM 输出略有减少。值得注意的是，生物炭的添加导致 >1000μm 大孔的显著增加，从而增强了土壤水的渗透。这些变化导致流量增加，进而导致降雨期间有机碳淋洗增加。因此，结果表明，生物炭应用后土壤结构和水力性质的变化值得关注，因为它们可能在通过径流过程影响 DOM 和其他溶质的传输方面发挥持续作用。
