水肥管理对稻田CH4排放及其全球增温潜势影响的评估

甲烷(CH_4)是主要温室气体之一,对全球增温的作用仅次于二氧化碳(CO_2)。稻田是CH_4的重要排放源,减少稻田CH_4排放对减缓气候变暖具有直接效应。为此,掌握稻田CH_4排放的规律和特征对控制和减少稻田CH_4排放尤为重要。为了解稻田温室气体排放的主要影响因子及影响程度,估算稻田温室气体全球增温潜势,寻求农田减排措施,我们通过收集已发表的文献建立了稻田CH_4排放的数据库,采用析因分析与回归分析方法对稻田CH_4日排放量和全球增温潜势特征和可能的影响因子进行了分析。结果表明,稻田CH_4日排放量和增温潜势均随土壤有机质背景含量的升高而增加,不同类型稻田CH_4日排放量大小依次为:双季稻晚稻双季稻早稻单季稻稻麦轮作晚稻;晚稻田CH_4的增温潜势大于早稻田。不同肥料处理条件下,稻田CH_4日排放量表现为:秸秆还田配施有机肥化学氮肥≈生物炭。控制灌溉水量可降低稻田CH_4的综合增温潜势,表现为:持续淹水晒田干湿交替控制灌溉。研究结果说明,稻田CH_4的产生与排放过程受土壤有机质含量、肥料管理和水分管理以及轮作制度等多种因素的共同影响,应依据不同土壤条件和种植制度,适当调整肥水管理,以减少稻田温室气体排放,降低其增温潜势。

Impact of water/fertilizer management on methane emission in paddy fields and on global warming potential

Methane (CH4) is a key greenhouse gas, second only to CO2 in term of contribution to global warming. Paddy field, as an important source of CH4 emission, has significant implications for global warming and climate change. In order to un-derstand the main factors of CH4 emission in paddy fields and its impact on global warming, this study calculated potential global warming and sought measures to mitigate CH4 emission in paddy fields. To do so, we collected data on CH4 emission in paddy fields in China using literatures published before 2015 (including journals and doctoral and master dissertations) and documented in CNKI net, ScienceDirect and SpringLink. Then daily CH4emission, global warming potential (GWP) and as-sociated factors influencing CH4 emission in paddy fields in China were analyzed using regression and factorial analyses. The results showed that daily emission of CH4in paddy field and GWP due to CH4 emission increased with increasing soil organic matter (SOM). The order of daily CH4 emission from paddy field was: late paddy field of double cropping rice > early paddy field of double cropping rice > single cropping paddy field > late paddy field of rice-wheat rotation. GWP due to CH4 emission in late paddy field was more than that in early paddy field for double cropping rice. The order of daily CH4 emission from paddy fields with different fertilizer managements was: ST (straw turnover) > NO (chemical nitrogen fertilizer with organic manure) > NF (chemical nitrogen fertilizer)≈ BI (biochar). Water management significantly affected CH4 emission from paddy fields with the order of continuous flooding (CF) > field drying (FDF) > flooding-drying alternation (FD) > control irrigation (CI). Proper water management also significantly reduced GWP due to CH4 emission. The order of GWP due to CH4 emission in early paddy fields, late paddy fields and single cropping rice paddy fields was also as follows: CF > FDF > FD > CI. The results suggested that CH4 emission was influenced by many factors, including soil SOM content, water and fertilizer man-agement, and basic soil conditions. However, agricultural management activities (e.g., water and fertilizer management, fertil-izer amount, fertilizer type) played a major role in CH4 emission in agricultural lands. This was influenced by soil nutrient conditions (soil SOM content and C:N ratio), climatic conditions (crop growth period, temperature and precipitation during growth period), management practices (fertilizer and water management), rotation system, and other factors. For a more accu-rate inventory of greenhouse gas emission and proposal of effective mitigation policies, it was critical to use appropriate prac-tices suitable to specific climatic, soil and cropping conditions, combined with rational nitrogen fertilizer application rate and water management.