【作者】 秦晓波；

【导师】 李玉娥； Hong Wang；

【作者基本信息】 中国农业科学院 ， 作物气象学， 2011， 博士

【摘要】 本研究利用手动静态箱-气相色谱法进行了连续5个生长季（2007²009）的双季稻田温室气体（GHGs）（甲烷（CH₄）和氧化亚氮（N₂O））排放观测,同时监测了环境因子的变化,包括气温、土壤温度、土壤pH值、氧化还原电位（Eh）、田间水层高度（H）、土壤有机质和土壤产气微生物菌群等。试验共设7个处理:翻耕稻草不还田（CWS）、免耕稻草不还田（NWS）、翻耕稻草不还田+硫包膜控释尿素（SCU）、免耕高茬还田（HN）、翻耕高茬还田（HC）、免耕覆盖还田（SN）以及免耕覆盖还田+淹灌（SNF）。分析了稻田GHGs排放季节变化规律,进行了GHGs排放与环境因子关系的多元回归,计算了各处理的综合温室效应,以探讨田间管理措施对华中典型双季稻田温室气体排放强度（GHGI）的影响,并优选减缓措施。主要结论如下:1)双季稻田温室气体排放具有一定的季节变化规律,表现在早晚稻差异和年际间的差异,年际间差异主要源于具体气候条件和水分状况的年际变异。CH₄排放季节变化规律比N₂O明显,绝大部分CH₄产生自水稻分蘖结束前的生长季前期,水分条件是水稻生长后期CH₄排放的控制因素。N₂O排放季节变异性和不确定性较大,观测到较多的负通量,早晚稻平均N₂O排放系数均低于1 %的IPCC推荐值。稻田CH₄和N₂O排放季节变化不具显著的交互效应。2)回归分析表明, Eh值-100⁰ mv和-150¹00 mv分别是CH₄和N₂O平均排放通量最大的范围,而pH值5⁶,H 1⁵ cm是稻田CH₄和N₂O平均排放通量最大的范围;稻田N₂O排放主要来自反硝化过程,其吸收通量则主要出现在田间水层较高时。3)稻田GHGs排放通量与土壤产气微生物的活性和数量密切相关,回归模型表明,土壤产甲烷菌数量可单独解释96 %的稻田CH₄排放;土壤硝化菌和反硝化菌数量则可联合解释75 %以上的N₂O排放通量。稻田土壤有机质的总量或形式对GHGs排放通量有显著影响,各处理CH₄排放通量与活性有机质含量显著相关,而N2O排放通量更依赖于土壤有机质总量。4) CH₄是稻田温室效应的主要贡献者,各种各时间尺度上水稻田CH₄温室效应都远大于N₂O,但随着时间尺度的增加,N₂O对温室效应的贡献比例上升。5)受水稻品种及其产量的影响,早晚稻各处理GHGI表现出不同的变化规律,纵观5个生长季平均值,SNF处理GHGI最大,而NWS处理最小,因此,NWS处理可作为减缓稻田GHGI的有效措施。考虑到各措施组合,免耕+常规尿素+稻草不还田组合是减缓稻田GHGI的优选耕作及施肥措施;间歇灌溉+中期晒田（增加间歇灌溉的频率及延长晒田日期）是减缓稻田GHGI的优选灌溉措施。更多还原

【Abstract】 To investigate the regularity of greenhouse gas intensity (GHGI) from typical double rice system of Central China under various field managements and to find a way to optimize the mitigation practices, five continuous rice growing seasons’measurement on greenhouse gases (GHGs) emission initiated from 2007 was conducted using manual static-GC (gas chromatography) method. Simultaneously, the seasonal variation of GHGs fluxes was monitored. Furthermore, the relationship of GHGs emission and environmental factors was analyzed by using the multivariate regression. There were 7 treatments involved, viz. CWS (Conventional tillage + without Straw residue + Urea), NWS (No till + without straw residue + Urea), SCU (Conventional tillage + without straw residue + Controled release urea), HN (High stubble residue + No till + Urea), HC (High stubble residue + Conventional tillage + Urea), SN (Straw cover + No till + Urea) and SNF (Straw cover + No till + Urea + Continuous flooding). The environmental elements include air temperature, soil temperature, soil redox potential (Eh), soil pH, field water table (H), soil organic matter and activity and population of soil microbes related to the production of GHGs emission from soil. The following were the main conclusions generated from this study:1) Pronounced seasonal and annual variation of GHGs emission has been observed, i.e. different regularity exists between early rice and late rice. Climate and soil water situation of each year contrlled the annual variance of GHGs emission. Most of methane fluxes occurred during the rice growing stage before the end of tiller, the water regime predominanted the emission of methane in the late rice growing stage. However, there was great variance and uncertainty of nitrous oxide from rice paddy, tons of negative fluxes of nitrous oxide have been measured over years, while, the average emission factor of nitrous oxide from early and late rice was less than the default value of IPCC. Furthermore, there was no significant trade-off between seasonal variation of methane and nitrous flux under the effect of same treatment.2) By the regression analysis, the largest average of methane emission occurred in the range of -100 mv<Eh<0 mv, 5<pH<6, 1 cm<H<5 cm, respectively, if only consider the unary regression, and the range of which the largest average nitrous oxide flux occurred was -150 mv<Eh<100 mv, 5<pH<6, 1 cm<H<5 cm, respectively. Denitrification is the predominant process of nitrous oxide production from double rice field, and the negative values of nitrous oxide flux occurred mostly during the situation of deep flooding, which favored the process of denitrification.3) Strong relationship exists between GHGs emission and activity as well population of soil microbes. Population of methanogens could explain individually 96 % of the variance of methane flux from rice paddy; while the combination of population of nitrifiers and denitrifiers could explain more than 75 % of variance of nitrous oxide flux. The effect of total amount or form of soil organic matter on seasonal average fluxes of GHGs was significant. For instance, methane flux depended on labile organic matter rather than total amount of soil organic matter, while, the total amount of soil organic matter was more important to nitrous oxide emissions than the labile organic matter.4) Most of the greenhouse effect of rice paddy was contributed by methane, calculation indexed that under impact of multiple managements and at different time scale, greenhouse effect of methane was extremely greater than nitrous oxide.5) Consideration of greenhouse effect and rice grain yield, SNF treatment caused maximum GHGI among the 7 managements, while NWS treatment, minmum. Consequently, we recommend that the combination of no till+normal urea+no straw residue as the optimized tillage and fertilizer management; the combination of intermittent irrigation+mid-season drainage (with more frequent drainages and prolonged draining days) as the water regime to mitigate the GHGI of rice paddy.更多还原