不同农作措施对稻田甲烷排放通量的影响

通过网室小区试验，观测得到单施尿素处理的甲烷排放通量为０．６４ｍｇ／ｍ＾２·ｈ；农家肥＋尿素处理、农家肥＋硝铵处理、农家肥＋硫铵处理的甲烷排放通量分别为５７．１，４２．１，３０．７ｍｇ／ｍ＾２·ｈ；农家肥＋硫铵＋间歇灌溉处理和农家肥＋尿素＋间歇灌溉处理的甲烷排放通量分别为２２．０和１４．７ｍｇ／ｍ＾２·ｈ。结果表明，以农家肥为基肥的５个处理的甲烷排放通量大大高于单施尿素处理的甲烷排放通量，表明高量     

土壤Eh和温度对稻田甲烷排放季节变化的影响

通过温室盆栽试验研究了土壤Ｅｈ和温度对稻田甲烷（ＣＨ４）排放季节变化时影响。结果表明,当水稻生长期土壤Ｅｈ处于适宜ＣＨ４产生的水平时,土壤Ｅｈ对ＣＨ４排放季节变化没有显著影响,这时土壤温度却显著影响ＣＨ４排放季节变化。土壤Ｅｈ的季节变化与ＣＨ４排放季节变化间存在显著相关性,而土壤温度却没有。     

不同施肥处理的一秀稻田甲烷排放量研究

通过大田生产性对比试验测得６种施肥处理的一秀稻田平均甲烷排放通量范围为３．９２－１０．２６ｍｇ／ｍ＾２．ｈ其中施堆肥稻田的甲烷排放通量最高，其它施肥处理依次排列为：马粪沼渣（１０．０２）、单施化肥（８．８１）、人粪尿沼渣（７．７６）、鸡粪沼渣（４．４８）和猪粪沼渣（３．９２ｍｇ／ｍ＾２．ｈ）。施用后面３种沼渣比施堆肥显（ａ＜０．０５）减少了稻田甲烷排放量。各处理稻田甲烷排放最高峰值期一致地出现在     

海莲红树林土壤CH4动态研究

对海南东寨港河港河口海莲红树林土壤ＣＨ４动态进行研究。Ｃ４通量季节变化规律为春季〉夏季〉秋季〉冬季,所有季节所有滩面其平均值为１．２１ｍｇ／（ｍ＾２．ｄ）。不同季节ＣＨ４产量平均值的大小顺序也为春季〉夏季〉秋季〉冬季,所有季节所有滩面其平均值为８．２８ｍｇ／（ｍ＾２．ｄ）,土壤理化因子对河港海莲林土壤ＣＨ４产生率的重要性依次为全氮〉ＳａＣｌＮａ＾４〉Ｎａ＾４〉Ｃｌ〉ＳＯ４＾２〉含水量〉总含增量〉有     

水分类型对土壤排放的温室气体组成和综合温室效应的影响

实验室研究表明,土壤排放出的温室气体（ＣＯ２、ＣＨ４和Ｎ２Ｏ）组成及总理显著地受土壤水分类型和施用秸秆的影响。连续淹水条件下,土壤仅排放微理的Ｎ２Ｏ,但排放出大量的Ｃ睡Ｃ敢条件下,土壤不排放Ｃ上键合的但排放出大量的Ｎ２Ｏ;虽然淹水的土壤排水促进Ｎ２Ｏ排放,但显著抑制ＣＨ４的排放,淹水好气交替处理的土壤其排放的ＣＯ２、ＣＨ４和Ｎ２Ｏ均在好气和连续淹水之间。根据各种温室产生温室效应的相对潜力,计算土壤     

土壤水分状况和质地对稻田N2O 排放的影响

１９９４年中国科学院封丘生态试验站通过小区试验研究了土壤质地和水分状况对稻田Ｎ２Ｏ排放的影响。结果表明稻田Ｎ２Ｏ排放主要受土壤水分状况的影响,淹水状态下,Ｎ２Ｏ排放很少,水分落于期间Ｎ２Ｏ排放量占水稻生长期Ｎ２Ｏ排放总量的８７．５０％～９８．６５％。土壤质地显影响稻田平均Ｎ２Ｏ排放通量,砂质土壤排放的Ｎ２Ｏ显或极显高于壤质和粘质土壤,水稻生长期砂质、壤质及粘质土壤的平均Ｎ２Ｏ排放通量分别为１３７．６３、８７．５４和６３．６μｇＮ２Ｏ－Ｎ／ｍ＾２．ｈ。     

冬小麦田氧化亚氮的排放

对１９９０－１９９２年间冬小麦田氧化亚氮排放的日变化和季节变化进行了研究，预测了Ｎ２Ｏ通量土壤温度的关系。在整个实验阶段，不施肥田和施肥田Ｎ２Ｏ能量的平均为１０．５μｔＮ／ｍ＾２．ｈ和２２．６μｇＮ／ｍ＾２．ｈ。小麦地上所施尿素排放Ｎ２Ｏ－Ｎ的释放系数为０．０９％。     

江浙沪地区农业生产中温室气体排放研究

根据ＩＰＣＣ Ｇｕｉｄｅｌｉｎｅｓ（１９９５）提供的方法，对１９９０年江浙沪地区农业生产过程中温室气体排放进行了统计计算。农业生产中主要的温室气体排放是甲烷，江浙沪地区农业生产中ＣＨ４排放量为２２０３Ｇｇ，而ＣＨ４的排放主要来自水稻田，占总农业部门ＣＨ４排放的８０．３％。     

淹水稻田甲烷产生和排放的研究现状

大气中温室气体如ＣＯ２、ＣＨ４和Ｎ２Ｏ等增加，导致全球气候变暖。ＣＨ４虽浓度相对较低，但其捕获热量的效率却比ＣＯ２高２０－３０倍，并以每年１％的速度增加，本文阐述了淹水稻田ＣＨ４排放过程及数量，稻田土壤类型，栽培措施对ＣＨ４产生与排放的影响，ＣＨ４排放与水稻生长关系。同时讨论了控制和缓解稻田ＣＨ４排放的途径。     

土壤质地对小麦和棉花田N2O排放的影响

１９９４年－１９９５年在中国科学院封丘生态试验站通过小区试验研究了土壤质地对小麦和棉花田Ｎ２Ｏ排放量的影响。结果表明,土壤质地明显影响小麦和棉花田Ｎ２Ｏ排放量,壤质土壤排放的Ｎ２Ｏ高于砂质和粘质土壤,小麦和棉花生长期壤质,砂质及粘质土壤的平均Ｎ２Ｏ排放通量分别为３７．９３,２３．８１,１２．９０及７０．３９,４５．８７,２７．８５μｇＮ２Ｏ－Ｎ／（ｍ＾２．ｈ）。     

Restoration of methane oxidation abilities of desiccated paddy soils after re-watering

Restoration of CH₄-oxidation activities of desiccated paddy soils and the NH₄⁺ effect after watering were investigated in laboratory incubations. Fresh paddy soil collected from an intermittently flooded rice field in Wuxi, Jiangsu province, showed a parabolic relationship between CH₄-oxidation activity and soil moisture with an optimum CH₄-oxidation rate at 71% water-holding capacity (WHC), while the paddy soil collected from a permanently flooded rice field in Yingtan, Jiangxi province, showed a much smaller CH₄-oxidation ability, which increased exponentially with soil moisture increasing from 28% WHC to 95% WHC at an initial CH₄ concentration of ~2,200 µl l^-1 and at room temperature (25°C). CH₄-oxidation ability was inversely related to N₂O emission and related positively with CO₂ emission in response to the change in soil moisture. Desiccated paddy soils lost their CH₄-oxidation abilities. However, this was recovered after the soils were re-watered. The restoration of CH₄-oxidation ability was directly dependent upon soil moisture and the rate of its restoration increased with increasing soil moisture content from 40% to 90% WHC. Addition of NH₄Cl at rates of 0-3.57 µmol g^-1 soil inhibited the restoration of CH₄-oxidation ability significantly (P<0.01), but the inhibitory effect was alleviated by a high soil moisture content. The restoration of CH₄-oxidation ability was much slower in the Yingtan soil than in the Wuxi soil. The studies show that the optimum moisture content of paddy soils for CH₄ oxidation depends on the methanotrophic bacteria in relation to the prevailing water regime; desiccation damages the CH₄-oxidation ability of permanently flooded paddy soil more severely than that of frequently well-drained soils.     

三江平原寒地稻田CH4、N2O排放特征及排放量估算

利用静态暗箱-气相色谱法,于2003-2006年对三江平原寒地稻田CH₄、N₂O通量进行了为期4年的田间原位观测研究。结果表明：三江平原寒地稻田CH₄和N₂O排放具有明显的季节变化,水稻生长季淹水期是CH₄排放的强源,稻田排水后CH₄排放显著下降,休闲期CH₄排放微弱或呈弱吸收汇,整个生长季CH₄排放呈现单峰型态,并随水稻植株生长和叶面积指数而变化;水稻生长季和休闲期N₂O排放通量都很小,冬季休闲期有时还出现微弱的吸收现象。生长季一般在施肥和表土落干时都会出现不同强度的排放峰,除了几次比较显著的排放峰值外,其它淹水状态下N₂O排放很弱;温度和土壤水分状况是影响稻田CH₄和N₂O排放的重要因子,稻田积水深度和气体排放无明显的相关性;水稻植株对稻田土壤CH₄排放起促进作用而对稻田土壤N₂O排放起抑制作用;稻田氮肥用量增加可以降低土壤CH₄排放,但却增加了N₂O的排放。根据试验数据对三江平原地区寒地稻田CH₄和N₂O排放总量估算值分别为0.1035 Tg/a和 0.0021 Tg/a。     

Nitrous oxide and methane emissions from different soil suspensions: effect of soil redox status

Four soil samples from fields of different land use [US (paddy field), China (paddy field) and Belgium (maize and wheat fields)] were incubated as soil suspension (soil:water ratio 1:4) to study the N₂O and CH₄ emission under different soil redox potential conditions. The results show that the N₂O emission was regulated within a narrow redox potential range of +120 to +250 mV, due to the balance of N₂O production and its further reduction to N₂. Methane emission occurred below a soil specific redox potential point, and the emission rates were inversely related to soil redox potentials. Both linear and exponential relationships between CH₄ emission and the soil redox potential were significant. By extrapolating the linear relationship of CH₄ emission against soil redox potential, the critical redox potentials for CH₄ production were estimated at about -170 (US paddy soil), -150 (Chinese paddy soil), -215 (Belgian maize soil), and -195 mV (Belgian wheat soil), respectively. In addition, the results indicate that a soil with a lower critical redox potential for CH₄ production had a higher CH₄ production potential. In this study, N₂O and CH₄ emissions were found to occur at a distinctly different soil redox potential condition. The range of soil redox potential values where both N₂O and CH₄ emissions were low was different for different soils, but it was situated between +120 and -170 mV. This is a wide redox potential range enabling field management practices to minimize both N₂O and CH₄ emissions from wetland ecosystems.     

Decreasing of methanogenic activity in paddy fields via lowering ponding water temperature: A modeling investigation

Methane (CH₄) is a potent greenhouse gas and the huge CH₄ fluxes emitted from paddy fields can prejudice the eco-compatibility of rice cultivation. CH₄ production in submerged rice crops is known to be highly influenced by water temperature. Hence, lowering ponding water temperature (LPWT) could be an option to mitigate CH₄ emissions from paddy environments when it is possible either to irrigate with slightly colder water or to increase ponding water depth. However, paddy soil is a complex environment in which many processes are simultaneously influenced by temperature, leading to a difficult prediction of LPWT effects. For this reason, LPWT efficiency is here theoretically investigated with a one-dimensional process-based model that simulates the vertical and temporal dynamics of water temperature in soil and the fate of chemical compounds that influence CH₄ emissions. The model is validated with literature measured data of CH₄ emissions from a paddy field under time-variable temperature regime. Based on modeling results, LPWT appears promising since the simulated reduction of CH₄ emissions reaches about −12% and −49% for an LPWT equal to −5 °C during the ripening stage only (last 30 days of growing season, when rice is less sensitive to temperature variations) and −2 °C over the whole growing season, respectively. LPWT affects CH₄ emissions either directly (decreasing methanogenic activity), indirectly (decreasing activity of bacteria using alternative electron acceptors), or both. The encouraging results provide the theoretical ground for further laboratory and field studies aimed to investigate the LPWT feasibility in paddy environments.     

稻鸭共作对不同栽培环境稻季CH4和N2O排放的影响

稻田是大气温室气体甲烷(CH₄)和氧化亚氮(N₂O)的重要排放源, 稻田温室气体减排一直是生态农业研究的热点。目前, 采用水稻品种选择利用、水分控制管理、肥料运筹管理、耕作制度调整以及种养结合模式等方法来减少稻田温室气体排放有较好实践效应, 但不同稻田栽培环境(露地、网室)基础上的稻鸭共作对麦秸全量还田的稻田温室气体排放特征及相关土壤理化特性关联性的影响尚为少见。本研究采用裂区设计, 在两种栽培环境条件下, 以无鸭子放养的常规稻作和麦秸不还田为对照, 在等养分条件下分析麦秸全量还田与稻鸭共作模式对稻田土壤氧化还原电位、CH₄排放量、产CH₄潜力及CH₄氧化能力、N₂O排放量及N₂O排放高峰期土壤反硝化酶活性、全球增温潜势、水稻产量的影响, 为稻田可持续生产和温室气体减排提供参考。结果表明, 麦秆还田增加了稻田产CH₄潜力、提高了CH₄排放量, 降低了稻田土壤反硝化酶活性、土壤氧化还原电位和N₂O排放量, 整体上导致全球增温潜势上升96.89%~123.02%; 稻鸭共作模式, 由于鸭子的不间断活动提高了稻田土壤氧化还原电位, 降低了稻田产CH₄潜力, 增强了稻田CH₄氧化能力, 从而降低稻田CH₄排放量, N₂O排放量虽有提高, 整体上稻鸭共作模式的全球增温潜势较无鸭常规稻田下降8.72%~14.18%; 网室栽培模式显著提高了稻田土壤氧化还原电位, 降低稻田产CH₄潜力、CH₄氧化能力和土壤反硝化酶活性, 减少了稻田CH₄和N₂O排放量, 全球增温潜势降低6.35%~13.14%。本试验条件下, 稻田土壤的CH₄氧化能力是产CH₄潜力的2.21~3.81倍; 相同环境条件下, 稻鸭共作和麦秸还田均能增加水稻实际产量, 网室栽培的所有处理较相应的露地栽培减少了水稻实际产量1.19%~5.48%。本试验表明, 稻鸭共作和网室栽培可减缓全球增温潜势, 稻鸭共作和麦秸还田能够增加水稻实际产量。     

Nitrous oxide and methane emissions during rice growth and through rice plants: effect of dicyandiamide and hydroquinone

There is growing interest in N₂O and CH₄ transport through rice plants, but very little information is available on the effects of inhibitors on these gaseous emissions during rice growth and through rice plants. The closed chamber technique was used to study the effect of the urease inhibitor hydroquinone (HQ) and the nitrification inhibitor dicyandiamide (DCD) on N₂O and CH₄ emissions. As rice plants grew, the N₂O emission through rice plants was significantly reduced in all treatments; N₂O emissions were always lower in the presence than in the absence of inhibitor(s). These variations paralleled those in NO₃^--N content of fresh rice plants. During the rice growth period, increasing NO₃^--N content in rice plants paralleled the increase in the N₂O emission through rice plants. Hence, NO₃^--N in young rice plants can substantially contribute to the plant-mediated N₂O flux. A substantial CH₄ emission through rice plants occurred at their vigorous growth stage; CH₄ emissions were always lower in the presence than in the absence of inhibitor(s). Under the experimental conditions, application of DCD, especially of DCD+HQ, could significantly improve the growth of rice, and reduce the emissions of N₂O and CH₄ during rice growth.     

烤田对种稻土壤甲烷排放的影响

本文通过温室盆栽试验研究了烤田对种稻土壤甲烷排放的影响。在水稻移栽后的第４３天和１０２天各烤田一次,持续时间分别为２８和１１３小时。结果表明种稻土壤在开台田后前１６和４２小时内有大量甲烷排放,且在烤田后不久土壤呈微干松软状态时出现甲烷排放高峰。随着烤田的延续,至土壤呈干裂状态时甲烷排放通量降为零,烤田能促进土壤闭蓄态甲烷的排放,烤田期间甲烷排放量点水稻生长期甲烷排放总量的５．９６％～１０．０５％。     

Elevated atmospheric CO2 reduces CH4 and N2O emissions under two contrasting rice cultivars from a subtropical paddy field in China

Elevated CO₂ (eCO₂) and rice cultivars can strongly alter CH₄ and N₂O emissions from paddy fields. However, detailed information on how their interaction affects greenhouse gas fluxes in the field is still lacking. In this study, we investigated CH₄ and N₂O emissions and rice growth under two contrasting rice cultivars (the strongly and weakly responsive cultivars) in response to eCO₂, 200 μmol mol-1 higher than the ambient CO₂ (aCO₂), in Chinese subtropical rice systems relying on a multi-year in-situ free-air CO₂ enrichment platform from 2016 to 2018. The results showed that compared to aCO₂, eCO₂ increased rice yield by 7%-31%, while it decreased seasonal cumulative CH₄ and N₂O emissions by 11%-59% and 33%-70%, respectively, regardless of rice cultivar. The decrease in CH₄ emissions under eCO₂ was possibly ascribed to the lower CH₄ production potential (MPP) and the higher CH₄ oxidation potential (MOP) correlated with the higher soil redox potential (Eh) and O₂ concentration ([O₂]) in the surface soil. The mitigating effect of eCO₂ on N₂O emissions was likely associated with the reduction of soil soluble N content. The strongly responsive cultivars had lower CH₄ and N₂O emissions than the weakly responsive cultivars, and the main reason might be that the former induced higher soil Eh and[O₂] in the surface soil and had larger plant biomass and greater N uptake. The findings indicated that breeding strongly responsive cultivars with the potential for greater rice production and lower greenhouse gas emissions is an effective agricultural practice to ensure food security and environmental sustainability under future climate change scenarios.     

Greenhouse gas emissions and mitigation measures in Chinese agroecosystems

Globally, CO₂, CH₄ and N₂O, contribute 60%, 15% and 5%, respectively, to the anthropogenic greenhouse effect. Atmospheric CO₂, CH₄ and N₂O are currently increasing by 0.5%, 1.1% and 0.3% per year, respectively. This paper reviews studies on greenhouse gas emission and mitigation measures in China in recent years. CH₄ emissions originate mainly from rice paddy fields, and are determined by soil characteristics, e.g., temperature, water content, pH and Eh conditions, and by land and crop management, e.g., land use, rice varieties and fertilizer application. Rice paddies emit N₂O in addition to CH₄, however, the N₂O and CH₄ emission patterns are quite different. Fertilization practices and field water conditions are major factors that control N₂O emissions. In order to minimize net greenhouse gas emissions from agricultural production systems, either sources of emissions must be reduced, or agricultural greenhouse gas sinks must be enhanced or newly created. Because the effects of greenhouse gas mitigation measures on each greenhouse gas are different, specific practices must be developed and adopted for the various gases. This paper discusses some promising greenhouse gas mitigation strategies to reduce net emissions from agroecosystems in China.     

水稻植株特性对稻田甲烷排放的影响及其机制的研究进展

水稻是我国最主要的口粮作物,稻田是重要温室气体甲烷的主要排放源之一。水稻植株特性既是水稻产量形成的关键因子,也是稻田甲烷排放的主要影响因子。但是,至今关于水稻植株对稻田甲烷排放的调控效应及其机制仍存在许多不一致的认识。为此,本文从形态特征、生理生态特征、植株-环境互作等方面,对现有的相关研究进行了综合论述。水稻地上部形态特征如分蘖数、株高、叶面积等对稻田甲烷排放的影响的研究结果不尽相同,起关键作用的是地下系统。优化光合产物分配在持续淹水的情况下可以减少稻田甲烷排放。提高水稻生物量在低碳土壤增加稻田甲烷排放,但在高碳土壤下降低甲烷排放。本文还明确了相关研究现状和存在的问题。在此基础上,作者认为未来应加强水稻根系形态及其生理特征,以及水稻植株-土壤环境(尤其是水分管理和养分管理)互作对稻田甲烷产生、氧化和排放影响的研究,在方法上应加强微区试验和大田试验的结合,并开展植株和稻田的碳氮互作效应及其机制研究,为高产低碳排放的水稻品种选育和低碳稻作模式创新提供理论参考和技术指导。