生物炭输入对旱作玉米氧化亚氮（N2O）排放的影响及菌根调节机制

Studies on N2O emission of agro-ecosystem so far are very active but controversial, the driving factors of N2O emission from farmland soil need to be further explored. Biochar applications have important effect on regulating soil N2O emission, however, their underling mechanisms are not clear. Although it is a consensus that arbuscular mycorrhizal (AM) fungi are important participants in soil nitrogen cycling, their regulative roles on biochar mediated N2O emissions have been ignored. We hypothesize that soil amendment with biochar can strengthen mycorrhizal performances of crop rhizosphere , and thus regulate soil denitrification and N2O emission. This proposed research will focus on rainfed maize crop system. We will conduct a field trial with soil benomyl sterilization, a root-box experiment with different root separation patterns, a pot experiment with different AM fungi types, and combine high-throughput sequencing and isotope tracer techniques to investigate (1) responses of AM fungi community composition and abundance to biochar soil amendment, (2) regulative effects of AM fungi on soil denitrification and N2O emission fluxes with different biochar application rates, and (3) regulative effects of different AM fungi types on soil denitrification and N2O emission fluxes when soil amendment with biochar. This study will disentangle the mycorrhizae-regulated mechanisms of N2O emission with biochar incorporated soils and provide a new theoretical basis for agricultural benefits of biochar application.

国内外关于农业生态系统N2O排放的研究与争论十分活跃，驱动农田土壤N2O排放的机理有待揭示。生物炭农用对土壤N2O排放具有重要影响，然而其调控机制尚不十分清楚。作为土壤氮素循环的重要参与者之一，丛枝菌根真菌对生物炭输入土壤N2O排放的调节作用并未引起足够的重视。我们假设“生物炭输入能够通过增强作物根际菌根功能而调控土壤反硝化过程及N2O排放”。本研究拟以雨养旱作玉米作物系统为研究对象，通过设计田间苯菌灵灭菌试验、根箱根系分隔试验和不同AM真菌类型盆栽控制试验，采用高通量测序手段和稳定性同位素示踪技术，研究（1）AM真菌对旱作农田生物炭输入的响应特征；（2）生物炭输入条件下AM真菌对土壤反硝化过程及N2O排放的调控效应；（3）生物炭输入条件下不同AM真菌类型对土壤反硝化过程及N2O排放的调控效应。研究结果将揭示生物炭输入影响旱作玉米N2O排放的菌根调节机制，为生物炭农用效应提供新的理论依据。

农田生态系统是重要的温室气体排放源之一，生物炭作为一种土壤改良剂在减少温室气体排放方面发挥一定作用，但其对土壤氧化亚氮（N2O）排放和丛枝菌根真菌的影响以及丛枝菌根真菌对N2O排放的调节机制尚不清楚。本研究以旱作玉米作物系统为研究对象，通过设计田间苯菌灵灭菌试验、根箱根系分隔试验和不同AM真菌类型盆栽控制试验探讨了施用生物炭对土壤AM真菌、N转化相关功能基因及N2O排放的影响及内在机制。研究结果表明：（1）施用生物炭改善旱作玉米农田土壤质量，随着生物炭施用量的增加，土壤pH和含水量呈增加趋势，土壤有机碳、全氮和铵态氮含量显著提高，土壤容重和硝态氮含量显著降低；（2）施用生物炭能够显著增加土壤微生物多样性，显著提高AM真菌基因丰度和侵染率，影响硝化和反硝化功能基因丰度，AM真菌与硝化、反硝化细菌存在氮素竞争关系，有效降低了旱作玉米土壤N2O的排放速率和累积排放量；（3）施用生物炭促进了玉米生长和氮素吸收，提高了干物质积累和产量，生物炭通过影响AM真菌调控旱作玉米氮素吸收和土壤N2O排放；（4）不同AM真菌类型对N2O排放的影响效果有差异，但施用生物炭均增加AM真菌基因丰度和侵染率、影响硝化和反硝化功能基因丰度，降低土壤N2O排放。本研究进一步阐明了生物炭影响N2O排放的AM真菌调节机制，对推动生物质炭化利用，减少农田温室气体排放具有重要意义。. 在项目执行期间，项目组人员在Chemosphere、Journal of Plant Growth Regulation、生态学报等期刊发表论文11篇，其中第一标注10篇；参加全国性学术研讨会4次；培养硕士研究生4名。