苏南地区茶园酸性土壤一氧化氮和氧化亚氮排放的同步观测研究

Soils are important source of atmospheric nitric oxide (NO) and nitrous oxide (N2O). Tropical and subtropical acidic soils are global hotspots of NO and N2O from terrestrial ecosystems. Soils are highly acidic in tea plantation in south Jiangsu province, while the characteristics and intensity of NO and N2O emissions from tea acidic soils are limited. There are three characteristics in tea plantation, namely, acidic soils, ridging farming and band-fertilization. Based on these three characteristics, we design a field in situ simultaneous measurement of NO and N2O fluxes from acidic soils in Yixin and Liyang green tea plantation, located at Tai lake region of south Jiangsu province, using static chamber combined with chemiluminescence NO-NO2-NOx analyzer and gas chromatography methods. The real-time PCR-DGGE is used to analyze the abundance of soil bacterial functional genes involved in soil nitrogen cycle. We aim at the process and microbial mechanism of NO and N2O fluxes from acidic soils of green tea plantation. We also focus on the emission intensity and the emission factor of fertilizer N for NO and N2O from acidic soils of green tea plantation. The results of this study would be helpful for minimizing the uncertainty in estimate of global NO and N2O emissions from subtropical acidic soils and mitigating NO and N2O emissions from acidic soils of tea plantation in China.

土壤是大气环境活性气体一氧化氮（NO）和氧化亚氮（N2O）的重要排放源。热带亚热带酸性土壤是全球NO和N2O的高排放区。苏南地区茶园土壤酸化严重，茶园酸性土壤NO和N2O排放特征和排放强度可能显著区别于大田作物系统。本项目根据苏南地区经营性绿茶生产中“土壤酸化严重、起垄种植和条带施肥”的三大特点，以江苏宜兴碧螺春和溧阳白茶两个绿茶品种的茶园酸性土壤为对象，采用静态箱-化学发光氮氧化物分析仪和静态箱-气相色谱法对不同施肥下土壤NO和N2O排放通量的多年同步原位观测，与定量PCR-DGGE分析技术检测土壤氮循环相关功能基因丰度相结合，研究茶园酸性土壤NO和N2O排放特征、排放过程及微生物学驱动机制，评估茶园酸性土壤NO和N2O排放强度和氮肥转化为NO+N2O的排放系数。研究结果为降低亚热带酸性土壤NO+N2O排放总量估算的不确定性，寻求我国茶园酸性土壤氮氧化物减排对策提供科学依据和数据支撑。

项目根据计划书内容，圆满完成了项目预期目标。项目针对我国亚热带茶园种植过程中“土壤酸化严重、起垄种植和带状施肥”的特点，以江苏省宜兴市和句容市碧螺春茶生产茶园的2个典型绿茶品种生产的酸性茶园土壤为研究对象，通过对不同施肥管理模式下茶园温室气体和NO排放通量的多年原位观测比较研究，了解茶园酸性土壤NO和N2O的排放特征、排放过程及驱动机制的影响规律，揭示了茶园酸性土壤NO和N2O排放的微生物分子机制，评估了不同施肥模式对亚热带茶园酸性土壤NO、N2O和茶园生态系统净温室气体排放的减排潜力，探讨不同施肥模式对茶园酸性土壤微生物群落组成、网络结构和土壤多功能性的影响。研究结果有助于了解亚热带酸性土壤温室气体和NO的排放规律，降低NO+N2O排放总量和排放系数估算的不确定性，为寻求我国茶园酸性土壤温室气体和NO减排对策提供数据支撑和科学依据。项目相关成果在国内外期刊上发表论文12篇，培养研究生数名，项目执行期间获得教育部自然科学一等奖1项。