不同植茶年限土壤一氧化氮排放及其微生物驱动机制研究

In recent years, nitric oxide (NO) has been receiving more attention, because it plays important roles in biogeochemical cycling, atmospheric chemistry and global warming. With favorable climate conditions and great fertilizer application, subtropical hilly tea fields are becoming an important area for NO emissions, Greater fertilizer application and low pH lead to different NO emission patterns in tea field compared to other land uses. As a perennial crop, tea plantation will bring changes in soil properties and affect NO emissions in successive years. However, few studies focus on NO emissions and the relevant mechanism in tea field soil, in which increase the uncertainty of accurately evaluation of NO emissions in tea field. By zooming in a commercial tea field in the hilly red-soil region in southern China, This project will i) observe NO emissions and relevant environmental factors in soil of different tea plantation age in field experiment to explore the change of NO emissions; ii) simulate the dry-wet cycles by incubation experiment and integrate the process of dry-wet cycles in field to probe the NO emissions and relevant mechanism; ⅲ) 15N double trace technology and high-throughput sequencing as well as qPCR technique will be used to decipher the different pathways and the nitrifiers as well as denitrifiers contributing to the NO emissions in soil of different plantation age in subtropical typical tea field. The project will be of great importance to provide data support to accurately evaluate the NO emissions and provide theoretical guidance for mitigating NO emissions in tea field based on further understanding of the mechanism.

一氧化氮（NO）在氮的生物地球化学循环、大气环境化学和全球变暖中起着重要作用。由于气候适宜和大量施肥以及持续扩张，亚热带丘陵茶园可能是NO的一个重要排放源。茶园高施肥、低pH及茶树多年生无轮作的特性导致其NO排放机理不同于其他土地利用类型。对茶园土壤NO排放规律及其相应机理研究的缺乏，为准确评估茶园土壤NO排放带来不确定性。本项目选取亚热带典型丘陵茶园为研究对象，通过田间试验，研究不同植茶年限土壤NO排放规律及主要影响因子，明确茶园土壤NO排放随着植茶年限增长的变化趋势；通过研究野外和室内模拟干湿交替过程，确定NO脉冲排放的规律及相应的微生物机理；通过15N双标记方法以及结合定量PCR和高通量测序等分子生物学手段，揭示不同植茶年限土壤NO产生的氮转化途径及微生物机理。项目实施有助于加深对茶园NO排放机理的认识，为更加准确评估茶园土壤NO排放提供数据支持，为减少茶园NO排放提供理论指导。

一氧化氮（NO）在氮的生物地球化学循环、大气环境化学和全球变暖中起着重要作用。由于气候适宜和大量施肥以及持续扩张，亚热带丘陵茶园可能是NO的一个重要排放源。茶园高施肥、低pH及茶树多年生无轮作的特性导致其NO排放机理不同于其他土地利用类型。对茶园土壤 NO排放规律及其相应机理研究的缺乏，为准确评估茶园土壤NO排放带来不确定性。本项目选取亚热带典型丘陵茶园为研究对象，通过研究不同植茶年限土壤NO排放规律，明确茶园土壤NO排放随着植茶年限增长的变化趋势；通过研究野外和室内模拟干湿交替过程，确定NO脉冲排放的规律及相应的微生物机理。结果表明，在恒定含水量条件下，种植15年的茶园土壤有最高的NO和N2O排放量以及对应的净硝化速率；NO主要在低含水量下有较高排放而N2O则在高含水量下排放较高；对应的15年植茶年限土壤微生物量氮（MBN）相对较低，说明相比其他年限土壤15年植茶年限土壤氮素更多以气体形式损失。干湿交替条件下，易导致NO和N2O脉冲排放，总的NO和N2O排放都呈现C5＞C15＞C30处理，说明干湿交替过程更容易导致低年限茶园土壤氮氧化物排放，且低年限的茶园土壤MBN变异较大，氮氧化物排放与中间时期50%WFPS含水量下MBN含量呈显著正相关。本研究结果综合表明，在估算亚热带地区茶园土壤NO和N2O排放随着植茶年限的变化存在较大的变异性，需要综合考虑不同年限茶园土壤氮氧化物排放才能更加准备评估茶园NO和N2O排放，为减少茶园NO和N2O排放提供理论指导。