生物炭对菜地土壤N2O产生过程的影响机理研究

Biochar has been advocated as an emerging strategy for mitigating nitrous oxide (N2O), sequestrating carbon dioxide and improving degrading soil quality for intensively managed vegetable fields in China. Considering that vegetable fields are usually receiving high doses of nitrogen (N) fertilizer and frequent irrigations, and consequently with obvious soil acidification and N2O emissions, we propose that several processes would have been undergoing and even play major roles in N2O emissions, such as heterotrophic nitrification, nitrifier denitrification, chemodenitrification as well as autotrophic nitrification and heterotrophic denitrification. By integrated using inhibitions of acetylene (C2H2) and/or oxygen (O2) combinations, 15N tracing technique -pool dilution methods and DNA sequencing technology in this study, we will quantify the contributions of different N2O production processes to the total N2O emissions from typically managed vegetable soils as compared with cereal crop agricultural soils. The influence of biochar amendment on the portions of different N2O production processes and N2O product ratios would be systematically assessed as compared with soils without biochar amendment. Several mechanisms involved in biochar influences on N2O emission would be differentiated such as targeting different processes, liming, aeration,effective time period, and microbial community structure and functional genes abundances. Two scientific hypothesis would be tested in this study including: ① Does nitrifier denitrification or heterotrophic nitrification occur as major N2O source process in acidic vegetable soils? ② How and why biochar amendment affect N2O production process and microbial community structures and functional gene abundances? Research results would improve scientific understanding of N2O source processes, N2O product ratios, biochar influence mechanisms and thus benefiting biochar application and N2O mitigation in Chinese vegetable fields.

生物炭是综合改良菜地土壤质量、减缓N2O排放的新兴战略。针对菜地施氮量高、浇灌频繁、土壤酸化、N2O排放高等现状，提出菜地土壤中可能同时存在多种途径产生N2O，除了反硝化和自养硝化作用外，还可能存在硝化细菌反硝化、异养硝化、化学反硝化等重要途径。本研究综合运用乙炔+氧气组合抑制法、15N同位素标记技术、DNA高通量测序技术，旨在①定量研究各种N2O产生途径对菜地N2O排放的贡献；②定量评价生物炭施用对各种N2O产生途径、产物N2O比例的影响；③阐明生物炭影响菜地各种N2O产生途径及产物N2O比例的主要控制因素与微生物驱动机制，明确生物炭能否减缓以及如何减缓菜地N2O排放的过程机理。拟解决的科学问题：①酸化菜地土壤是否存在硝化细菌反硝化或异养硝化作用及其贡献；②生物炭如何影响菜地各种N2O产生过程及其微生物驱动机制。研究结果将为减缓菜地N2O排放以及生物炭综合运用提供科学依据。

生物质炭是综合改良菜地土壤质量、减缓N2O排放的新兴战略。针对菜地施氮量高、浇灌频繁、土壤酸化、N2O排放高等现状，本研究综合运用抑制剂法、15N同位素标记技术、DNA高通量测序技术，定量研究生物质炭和硝化抑制剂对典型菜地活性气态氮排放强度的影响，辨析生物质炭施用后菜地N2O的产生途径，对比生物质炭对菜地和稻田温室气体排放关键微生物功能基因丰度的影响。本研究阐明了生物质炭如何影响菜地N2O产生过程及其微生物驱动机制，追踪生物质炭老化过程对不同菜地土壤N2O排放的影响，揭示了生物质炭减缓稻田和菜地温室气体排放的长期效应，研究结果为减缓菜地N2O排放以及生物质炭综合运用提供科学依据。研究成果被《科技日报》等报道(04/15/2015)，已发表标注本基金资助学术论文SCI 25篇（其中第一标注19篇），中文15篇（其中第一标注9篇）。项目申请人荣获江苏省十大青年科技之星；培养毕业硕士研究生9名，博士研究生5名，其中3名研究生获得国家奖学金（张晓旭、范长华、毕智超）。