南方红壤丘陵经营性茶园氧化亚氮减排机理和调控研究

With favorable climate conditions and great fertilizer applications, tea fields are becoming a hotspot of nitrous oxide (N2O) emissions in the hilly red-soil region of southern China. Nowadays, the continuous expansion of tea plantation and high inputs of nitrogen fertilizers are increasing the risk of greenhouse gas emissions. However, there are lacks of feasible measures and methods for mitigating N2O emissions from tea fields without compromising economic profits. By zooming in a commercial tea field in the hilly red-soil region in southern China, this proposal will: i) distinguish the contributions of nitrification, denitrification and other processes to N2O emissions from tea fields using the 15N isotope tracer technology and the robotized incubation system, analyze the main controlling factors of the processes, and construct a tea soil-specific N2O emissions mathematic module for the WNMM model and verify it; ii) nail down the full story of high N2O emissions and the mitigation mechanism by applying the WNMM model to simulate the historic data of the in-situ measurement of N2O emissions from tea fields; and iii) by considering fertilization, applications of bio-materials and nitrification inhibitors and ecological engineering to form treatments, carry out a multiple year-round N2O mitigation field observation experiments of univariate and multivariate, and screen out feasible N2O mitigation measures in senses of science, agronomy and economy by assessing tea production and quality, CO2 equivalences, nitrate leaching and input-output cost analysis of the treatments. The outcomes of the project will be of a great importance to improve our understanding of the N2O emissions mechanism, reduce the risk of greenhouse gas emissions of tea fields and promote the regional agriculture sustainability in southern China.

适宜气候和大量施肥使茶园成为南方红壤丘陵区氧化亚氮（N2O）的排放热区。茶园持续扩张和高氮肥投入，加剧了其温室气体排放风险。如何进行茶园N2O减排，尚无科学可行的措施和方法。本项目拟以南方红壤丘陵经营性茶园为研究对象，应用15N同位素示踪技术和自动化培养生物试验系统定量分析茶园土壤硝化、反硝化或其它过程对N2O排放的贡献，揭示不同过程的关键控制因子，构建该土壤N2O排放的数学模块（基于WNMM模型）并验证；应用WNMM模拟已有的茶园N2O排放观测数据，分析高排放原因和明确减排机制；在综合考虑施肥、生物质和硝化抑制剂应用以及生态/生物工程实施的基础上，开展单因素和多因素组合田间减排试验以多年监测茶园N2O排放，评价茶叶产量及品质、温室气体CO2当量、成本收益等以筛选科学可行、经济合理的减排措施。本研究对完善茶园N2O排放机理认知、降低茶园温室气体排放风险和促进区域农业可持续发展具有重要意义。

本项目以南方红壤丘陵经营性茶园为研究对象，应用室内微生物测试和培养试验系统定量分析茶园土壤硝化、反硝化或其它过程对N2O排放的贡献，揭示了不同过程的关键控制因子，构建了基于WNMM模型的土壤N2O排放的数学模块并验证；应用WNMM模拟了历史茶园N2O排放观测数据，分析了高排放原因和明确减排机制；在综合考虑施肥、生物质炭和硝化抑制剂应用以及生态/生物工程实施的基础上，开展单因素和多因素组合田间减排试验以多年监测茶园N2O排放，评价茶叶产量、成本收益等以筛选科学可行、经济合理的减排措施。研究结果表明，茶园土壤的N2O主要来源于反硝化过程（>75%），增加土壤酸碱性措施如使用碱性生物质炭、常规和大颗粒尿素深施、施用缓释肥料、间作能分泌生物硝化抑制剂的高粱等减排处理能显著减少茶园土壤的N2O排放33%~51%，其中大颗粒尿素深施和施用缓释肥料具有较好的实际农艺推广价值。本研究对完善茶园N2O排放机理认知、降低茶园温室气体排放风险和促进区域农业可持续发展具有重要意义。