【作者】 汤宏；

【导师】 吴金水； 张杨珠；

【作者基本信息】 湖南农业大学 ， 土壤学， 2013， 博士

【摘要】 大气温室气体浓度持续升高而导致全球气候变暖是当前广受关注的环境问题。稻田是大气温室气体的重要排放源,受到广大农业环境科学家的重视。本研究以我国亚热带地区稻田生态系统为研究对象,采用田间小区试验研究了不同秸秆还田量和不同水分管理方式下稻田CH4和N2O的排放特征,土壤-水稻系统呼吸特征和土壤异养呼吸特征；采用室内恒温培养试验研究了外加不同有机物料对温室气体排放的影响,初步揭示了稻草还田后温室气体产生的机理。主要研究结果如下：(1)高量秸秆还田(6t.hm-2)且长期淹水处理CH4的累积排放量是无秸秆还田且长期淹水处理的4.7倍,高量秸秆还田且间歇灌溉处理和低量秸秆还田(3t·hm-2)且间歇灌溉处理CH4的累积排放量分别是无秸秆还田且间歇灌溉处理的8.8和4.8倍；无秸秆还田且长期淹水处理CH4的累积排放量是无秸秆还田且间歇灌溉处理的2.7倍,高量秸秆还田且长期淹水处理CH4的累积排放量是高量秸秆还田且间歇灌溉处理的1.2倍(以下数据均为三个稻季的均值)；烤田不仅减少了烤田期间CH4排放量,而且还减少烤田后复水期间CH4的排放。无秸秆还田时,在烤田期间和烤田后复水期间,烤田比不烤田减少了57.6%和86.3%的CH4排放,高量秸秆还田时则减少了14.1%和81.7%的CH4排放。无秸秆还田且长期淹水处理、无秸秆还田且间歇灌溉处理、低量秸秆还田且间歇灌溉处理、高量秸秆还田且间歇灌溉处理和高量秸秆还田且长期淹水处理在分蘖期CH4的排放量分别占全生育期排放量的34.2%、56.9%、72.2%、73.6%和62.8%；各处理在有水稻种植时CH4的排放量分别为无水稻种植时的3.1、2.4、1.4、2.2和1.9倍；CH4排放与稻田环境因子(土壤温度和水层深度)、土壤因子和生物因子关系密切。(2)在有水稻种植时,高量秸秆还田且长期淹水处理N20的累积排放量是无秸秆还田且长期淹水处理的36.8%,高量秸秆还田且间歇灌溉处理、低量秸秆还田且间歇灌溉处理处理N20的累积排放量分别是无秸秆还田且间歇灌溉处理的47.0%和70.5%；无秸秆还田且长期淹水处理N2O的累积排放量是无秸秆还田且间歇灌溉处理的77.0%,高量秸秆还田且长期淹水处理N20的累积排放量是高量秸秆还田且间歇灌溉处理的60.8%；无水稻种植时,高量秸秆还田且长期淹水处理N20的累积排放量是无秸秆还田且长期淹水处理的166.0%,高量秸秆还田且间歇灌溉处理和低量秸秆还田且间歇灌溉处理N2O的累积排放量分别是无秸秆还田且间歇灌溉的93.0%和74.9%；高量秸秆还田且长期淹水处理N20的累积排放量是无秸秆还田且间歇灌溉处理的12.4%,高量秸秆还田且长期淹水处理N20的累积排放量是高量秸秆还田且间歇灌溉处理的26.3%；相对于不烤田,烤田既增加了烤田期间N20的排放量,也增加了烤田后复水期间N20的排放。各稻季N20的排放主要集中在水稻生长的分蘖期、拔节期和完熟期；无水稻种植时,各处理N20排放量分别为有水稻种植时对应处理的1.2、7.4、10.2、24.2和5.0倍；N20排放与稻田环境因子(土壤温度和水层深度)和土壤因子关系密切。(3)高量秸秆还田且长期淹水处理土壤-水稻系统总呼吸量是无秸秆还田且长期淹水处理的1.2倍,高量秸秆还田且间歇灌溉处理和低量秸秆还田且间歇灌溉处理分别是无秸秆还田且间歇灌溉处理的1.02和0.98倍；无秸秆还田且长期淹水处理是无秸秆还田且间歇灌溉处理的0.91倍,高量秸秆还田且长期淹水处理是高量秸秆还田且间歇灌溉处理的1.05倍；高量秸秆还田且长期淹水处理土壤异养呼吸量是无秸秆还田且长期淹水处理的1.81倍,高量秸秆还田且间歇灌溉处理和低量秸秆还田且间歇灌溉处理分别是无秸秆还田且间歇灌溉处理的1.36和1.08倍；无秸秆还田且长期淹水处理是无秸秆还田且间歇灌溉处理的0.65倍,高量秸秆还田且长期淹水处理是高量秸秆还田且间歇灌溉处理的0.83倍；一般来说,烤田既增加了烤田期间土壤异养呼吸量,也增加了烤田后复水期间土壤异养呼吸量；三个稻季,各处理土壤-水稻系统总呼吸量分别为土壤异养呼吸量的6.5、4.5、4.2、3.5和4.3倍；土壤-水稻系统总呼吸速率和土壤异养呼吸速率与土壤温度、水层深度等环境因子关系密切；土壤-水稻系统总呼吸量与水稻地上部分和地下部分生物量均呈极显著正相关；土壤-水稻系统总呼吸速率和土壤异养呼吸速率均与土壤DOC含量呈显著或极显著正相关。(4)水分管理和秸秆还田对各稻季各处理间水稻产量的影响不显著；水分管理影响土壤异养呼吸和水稻净初级生产力,从而影响稻田生态系统与大气间CO2的净交换量的大小,是影响稻田NEE值的主导因素；秸秆还田对NGHGE和GHGI有显著或极显著的影响,是影响NGHGE和GHGI的主导因素；从年度时间尺度来看,各处理稻田均没有增加温室气体的净排放。(5)添加原稻草处理CH4累积排放量最高,对土壤原有有机碳转化成CH4的激发效应大；添加腐熟稻草、去除低分子有机物的稻草和低分子有机物的各处理CH4的累积排放量明显高于不添加有机物料处理,对土壤原有有机碳转化成CH4都产生激发效应；CH4排放量与土壤质地密切相关；添加原稻草处理CO2累积排放最高,稻草对土壤原有有机碳分解的激发效应大；添加低分子有机物处理CO2的累积排放量高于不添加有机物料处理,对土壤原有有机碳的分解产生·一定的激发效应；添加腐熟稻草和去除低分子有机物处理CO2的累积排放量和不添加有机物料处理无明显差异,对土壤原有有机碳分解的激发效应不明显；添加含低分子有机物的外源有机物料比添加纤维素等单一物质产生的激发效应大,土壤有机碳的分解对不同外源物料激发效应的响应不同；CO2的产生主要集中在稻草中易分解物质的快速分解阶段；在稻草中易分解物质的快速分解阶段和难分解物质的缓慢分解阶段,均有CH4产生,但以快速分解阶段产生为主。不添加有机物料处理N2O的累积排放量最高,添加各种有机物料减少了N2O的累积排放量,N2O累积排放量的减少程度与土壤质地密切相关；CH4、N2O和CO2的累积排放量与土壤因子关系密切。因土壤不同与各土壤因子的相关关系存在差异。更多还原

【Abstract】 Global warming result from rising of atmospheric concentration of greenhouse gases is an environment issue of common concern among all people. Paddy field is a major source of greenhouse gases in the atmosphere, which are paid more attention by more agriculture environmental scientists. This study was carried out in paddy field ecosystems of subtropical regions. The characteristics of CH4emission, N2O emission, soil and rice system respiration and soil heterotrophic respiration under different rice straw incorporation rate and water regime were studied by using field plot experi-ment. We also carried out thermostatic incubation experiment and to research the effect of external source organic materials incorporation on greenhouse gases emission, and revealed the mechanism of the source of greenhouse gases after rice straw incorporation. The main results of this study are presented as follows:(1) CH4cumulative emission of high rice straw incorporation rate (6t·hm-2) and continuous flooding treatment is4.7times as much as that of no rice straw incorporation and continuous flooding treatment. CH4cumulative emission of high rice straw incorporation rate and intermittent flooding treatment, low rice straw incorporation rate (3t·hm-2) and intermittent flooding treatment is8.8and4.8times as much as that of no rice straw incorporation and intermittent flooding treatment, respectively. CH4cumulative emission of no rice straw incorporation and continuous flooding treatment is2.7times as much as that of no rice straw incorporation and intermittent flooding treatment. CH4cumulative emission of high rice straw incorpora-tion rate and continuous flooding treatment is1.2times as much as that of high rice straw incorporation rate and intermittent flooding treatment (average value of three rice season); Soil drying not only reduced CH4emission of soil drying period, but also reduced CH4emission of re-flooding period. Under no straw incorporation, compared with non-drying, soil drying reduced CH4emission by57.6%and86.3%, during soil drying and re-flooding period, respectively. Under high straw incorporation rate, compared with non-drying, soil drying reduced CH4emission by14.1%and81.7%, during soil drying and re-flooding period, respectively. CH4emission rate of no rice straw incorporation and continuous flooding treatment, no rice straw incorporation and intermittent flooding treatment, low rice straw incorporation rate and intermittent flooding treatment, high rice straw incorporation rate and intermittent flooding treatment and high rice straw incorporation rate and continuous flooding treatment at tillering stage was accounted for34.2%,56.9%,72.2%,73.6%and62.8%of the whole stages, respectively. CH4emission rate of each treatment in the rice planting region is3.1,2.4,1.4,2.2and1.9times as much as that of the corresponding treatment in the non-rice planting region, respectively. CH4emission was closely related to environmental factors (soil temperature and depth of the water), soil factors and biological factors.(2) In the rice planting region, N2O cumulative emission rate of high rice straw incorporation rate and continuous flooding treatment accounted for36.8%of no rice straw incorporation and continuous flooding treatment; N2O cumulative emission rate of high rice straw incorporation rate and intermittent flooding treatment and low rice straw incorporation rate and intermittent flooding treatment accounted for47.0%and70.5%of no rice straw incorporation and intermittent flooding treatment, respectively; N2O cumulative emission rate of no rice straw incorporation and continuous flooding treatment accounted for77.0%of no rice straw incorporation and intermittent flooding treatment, high rice straw incorporation rate and continuous flooding treatment accounted for60.8%of high rice straw incorporation rate and intermittent flooding treatment; In the non-rice planting region, N2O cumulative emission rate of high rice straw incorporation rate and continuous flooding treatment accounted for166.0%of no rice straw incorporation and continuous flooding treatment; N2O cumulative emission rate of high rice straw incorporation rate and intermittent flooding treatment and low rice straw incorporation rate and intermittent flooding treatment accounted for93.0%and74.9%of no rice straw incorporation and intermittent flooding treatment, respectively; N2O cumulative emission rate of no rice straw incorporation and continuous flooding treatment accounted for12.4%of no rice straw incorporation and intermittent flooding treatment, high rice straw incorporation rate and continuous flooding treatment accounted for26.3%of high rice straw incorporation rate and intermittent flooding treatment; Relative to non-drying, soil drying not only increased N2O emission of soil drying period, but also increased N2O emission of re-flooding period. N2O emission each season rice are mainly concentrated in tillering stage, jointing stage and mature stage; N2O emission rate of each treatment in the non-rice planting region is1.2,7.4,10.2,24.2and5.0times as much as that of the corresponding treatment in the rice planting region, respectively. N2O emission was closely related to environmental factors (soil temperature and depth of the water) and soil factors(3) Total respiration rate of soil and rice system of high rice straw incorporation rate and continuous flooding treatment is1.2times as much as that of no rice straw incorporation and continuous flooding treatment; Total respiration rate of soil and rice system of high rice straw incorporation rate and intermittent flooding treatment and low rice straw incorporation rate and intermittent flooding treatment is1.02and0.98times as much as that of no rice straw incorporation and intermittent flooding treatment, respectively; Total respiration rate of soil and rice system of no rice straw incorporation and continuous flooding treatment is0.91times as much as that of no rice straw incorporation and intermittent flooding treatment, high rice straw incorporation rate and continuous flooding treatment is1.05times as much as that of high rice straw incorporation rate and intermittent flooding treatment; Soil heterotrophic respiration rate of high rice straw incorporation rate and continuous flooding treatment is1.81times as much as that of no rice straw incorporation and continuous flooding treatment; Soil heterotrophic respiration rate of high rice straw incorporation rate and intermittent flooding treatment and low rice straw incorporation rate and intermittent flooding treatment is1.36and1.08times as much as that of no rice straw incorporation and intermittent flooding treatment, respectively; Soil heterotrophic respiration rate of no rice straw incorporation and continuous flooding treatment is0.65times as much as that of no rice straw incorporation and intermittent flooding treatment, high rice straw incorporation rate and continuous flooding treatment is0.83times as much as that of high rice straw incorporation rate and intermittent flooding treatment; In general,soil drying not only increased soil heterotrophic respiration of soil drying period, but also increased soil heterotrophic respiration of re-flooding period. Total respiration rate of soil and rice system of each treatment is6.5,4.5,4.2,3.5and4.3times as much as soil heterotrophic respiration rate of the corresponding treatment, respectively; Total respiration rate of soil and rice system and soil heterotrophic respiration rate were closely related to environmental factors, such as temperature, water depth; Total respiration rate of soil and rice system were extremely positive correlated to rice biomass above the ground and under the ground. Total respiration rate of soil and rice system and soil heterotrophic respiration rate were significantly or extremely positive correlated to soil DOC content.(4) Water regime and rice straw incorporation had no significant effect on the rice yield of each rice season; Water regime had effect on soil heterotrophic respiration and net primary production of rice, thus affected the net CO2exchange between paddy field ecosystem and atmosphere, which was the dominant factor of affecting the paddy NEE (Net Ecosystem CO2Exchange) value. Rice straw incorpora-tion had significantly or extremely effect on NGHGE (Net Greenhouse Gas Emission) and GHGI (Greenhouse Gas Intensity), which was the dominant factor affecting the NGHGE and GHGI. On annual time scale, the rice paddy fields did not increase net greenhouse gases emission.(5) CH4cumulative emission of adding original rice straw was the highest, and which had big priming effect on soil intrinsic organic carbon; CH4cumulative emissi-ons of adding decomposed straw, low molecular organic material and non-active ingre-dient straw were obviously higher that of non-adding organic materials treatment, which had priming effect on soil intrinsic organic carbon; CH4emission rate was closely related with soil texture. CO2cumulative emission of adding original rice straw was the highest, and which had big priming effect on soil intrinsic organic carbon; CO2cumulative emission of adding low molecular organic material treatment was higher that of non-adding organic materials treatment, and which had priming effect on soil intrinsic organic carbon decomposition; CO2cumulative emission of adding decomposed straw and non-active ingredient straw treatment was no significant differences as compared with non-adding organic materials treatment, and it’s priming effect on soil intrinsic organic carbon decomposition was not obvious; Priming effect of adding exogenous organic materials containing low molecular organic material was stronger than that of adding single material such as cellulose, and response of soil organic carbon decomposition to different exogenous material was different;CO2produced mainly at rapid decomposition stage of the easy decomposition material in rice straw;CH4produced at rapid decomposition stage of the easy decomposition material and slow decomposition stage of the difficult decomposition material in rice straw, but it produced mainly at rapid decomposition stage.N2O cumulative emission rate of S treatment is the highest, N2O cumulative emission rate was reduced due to adding the various organic materials, reduction degree of N2O cumulative emission rate was closely related with soil texture; CH4, N2O and CO2cumulative emission rate were closely associated with soil factors. The relationship between CH4, N2O and CO2cumulative emission rate and soil factors existed difference due to different soil.更多还原