水肥管理对稻田土壤甲烷和氧化亚氮排放的影响

就稻田水肥管理以甲烷和氧化亚氮排放的影响研究进行了综述，文章分析表明，甲烷和氧化亚氮的排放条件存在明显的反位关系，即有利于甲烷排放的水分条件往往不利于氧化亚氮的排放，稻田温室气体的排放与水分管理的历史有明显的关系，不同的肥料施用对甲烷和氧化亚氮排放影响的机制不同。因此，要真正有效地控制温室气体的排放必须首先弄清甲烷和氧化亚氮在不同条件下的排放关系。     

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     

农业土壤排放氧化亚氮的影响因素分析

氧化亚氮（Ｎ２Ｏ）是重要的温室气体之一。本文从施肥、灌溉、耕作、种植作物及土地用作改变等方面论述了农业活动对土矿氧化亚氮的影响，并总结限减排措施。     

农业土壤排放氧化亚氮的影响因素分析

氧化亚氮（N₂O）是重要的温室气体之一。本文从施肥、灌溉、耕作、种植作物及土地用途改变等方面论述了农业活动对土壤排放氧化亚氮的影响，并总结了减排措施。     

水分管理影响稻田氧化亚氮排放研究进展

稻田作为大气中N2O的重要来源而倍受关注.硝化反硝化是土壤中N2O生成的两个主要的微生物过程,水分管理是影响稻田土壤N2O产生排放的重要因素之一.本文综述了水稻生长期和非水稻生长期水分管理对N2O排放的季节变化、N2O产生和排放途径、N2O-N排放系数以及与N2O产生排放过程相关的土壤N素形态、浓度和土壤酶活性的影响,并提出了有待研究的问题.     

影响氧化亚氮形成与排放的土壤因素

土壤中Ｎ２Ｏ形成、散发与地球温室效应有密切关系。土壤中Ｎ２Ｏ是通过硝化和反硝化过程形成的。由于硝化和反硝化过程中均产生Ｎ２Ｏ，故凡影响这两个过程的因素都会对Ｎ２Ｏ的形成发生作用。土壤通气状况、土壤水分含量、土壤氮素状况与氮肥施用、土壤ｐＨ、土壤有机物含量与组成、土壤质地结构及耕作利用等土壤因素都会影响Ｎ２Ｏ的形成与排放。     

不同有机肥对稻田温室气体排放及产量的影响

为研究有机肥施入稻田对温室气体排放的影响,设置猪粪、鸡粪和稻草分别与化肥混施处理,利用静态箱法-气相色谱仪监测稻田甲烷(CH_4)和氧化亚氮(N_2O)排放通量并进行分析。研究结果表明,化肥处理(CF)CH_4季节排放为202.1、279.9和332.5 kg/hm~2,与猪粪(PM)无显性差异,明显低于鸡粪(CM)和稻草(RS)处理;CF处理N_2O排放总量最高,与有机肥处理无显著性差异;CH_4季节排放通量与土壤Eh值呈极显著负相关关系,与土壤温度呈极显著正相关关系;肥料中不同活性有机碳质量分数为18.4~114.5 g/kg,肥料中被167 mmol/L高锰酸钾氧化的有机碳(ROC167)与稻田CH_4排放总量呈显著正相关关系(相关系数为0.872,P0.05);施有机肥第三年水稻平均产量比CF处理增加14.3%(P0.05);不同有机肥中,以PM处理的增温潜势和温室气体排放强度最小,与不施肥和CF处理无显著性差异,猪粪的ROC167含量低,能较好的协调环境与产量之间关系,是值得推荐的有机肥种类。     

不同施肥处理对稻田氧化亚氮排放的影响

2004年在湖南省望城县黄金乡长期肥料监测站对不同施肥处理稻田中N2O排放通量进行了连续观测,发现不同施肥处理稻田中N2O排放季节变化具有一致的规律:生长中前期N2O排放量较小,晒田及之后排放量较大。各施肥处理N2O排放的差异早晚稻不同,早稻各处理间差异不显著,NPK处理排放量最大,为1.48kg.hm2;晚稻各处理差异极显著(p<0.01),NPKS处理排放量最大,为1.40kg.hm2;同是有机肥和化肥配施,早稻NKM处理N2O排放大于NPKS处理,两者差异不显著,而晚稻NPKS处理N2O排放远大于NKM处理,二者差异显著(p<0.05)。稻田水分状况也影响N2O排放,淹水期N2O排放较少,落干期N2O排放较多。     

秸秆还田对农田棕壤氧化亚氮排放动态的影响

通过田间试验,采用静态箱法对不同量秸秆还田(单施氮肥、半量秸秆还田、全量秸秆还田)下不同时期土壤氧化亚氮排放动态进行了研究。结果表明,和单施氮肥相比,秸秆覆盖还田提高了土壤氮素积累,也同时影响土壤N_2O排放动态。在玉米生长期间,半收获量秸秆还田增加了7.8%的N_2O排放,全量秸秆还田降低了2.2%的N_2O排放,与土壤铵态氮变化一致;玉米收获后,秸秆还田显著增加了N_2O排放,增幅分别为6.7%(半量秸秆还田)和22.6%(秸秆全量还田)。试验期间单施氮肥、半量秸秆还田和全量秸秆还田三个处理N_2O排放的年累计量分别为1183 g hm~(-2)、1269 g hm~(-2)和1294 g hm~(-2)。尽管秸秆还田增加了总的N_2O排放,但是,由于秸秆增加了土壤氮素的投入,当以N_2O损失的氮素占总氮素投入的比例进行估算时,全量秸秆还田损失率最低为0.52%、半量秸秆还田为0.57%、单施氮肥为0.59%。由此可见,秸秆还田在增加土壤肥力的同时,降低了单位氮素的氧化亚氮损失,有利于氮素在土壤中的保留。     

旱地农田氧化亚氮排放研究进展

针对北方旱地农田N2O的产生机理、排放规律及影响因素进行综述,指出影响旱地土壤N2O排放的主要因素是施肥、灌水和农田耕作等人为因素,合理施氮和增加土壤碳贮存是缓解温室气体排放的重要途径,并提出今后应进一步加强不同立地条件下的长期高频农田生态系统N2O排放观测、N2O产生的关键微生物过程与机理与相关观测及通量相结合和农田温室气体排放模型的应用等方面的研究。     

Controlled irrigation and drainage of a rice paddy field reduced global warming potential of its gas emissions

The effect of controlled drainage on methane (CH₄) and nitrous oxide (N₂O) emissions from a paddy field under controlled irrigation (CI) was investigated by controlling the sub-surface drainage percolation rate with a lysimeter. CI technology is one of the major water-saving irrigation methods for rice growing in China. Water percolation rates were adjusted to three values (2, 5, and 8 mm d^?1) in the study. On the one hand, the CH₄ emission flux and total CH₄ emission from paddy fields under CI decreased with the increase of percolation rates. Total CH₄ emissions during the growth stage of rice were 1.83, 1.16, and 1.05 g m^?2 in the 2, 5, and 8 mm d^?1 plots, respectively. On the other hand, the N₂O emission flux and total N₂O emissions from paddy fields under CI increased with the increase of percolation rates. Total N₂O emissions during the growth stage of rice were 0.304, 0.367, and 0.480 g m^?2 in the 2, 5, and 8 mm d^?1 plots, respectively. The seasonal carbon dioxide (CO₂) equivalent of CH₄ and N₂O emissions from paddy fields under CI was lowest in the 2 mm d^?1 plot (1364 kg CO₂ ha^?1). This value was 1.4% and 19.4% lower compared with that in the 5 and 8 mm d^?1 plots, respectively. The joint application of CI and controlled drainage may be an effective mitigation strategy for reducing the carbon dioxide equivalents of CH₄ and N₂O emissions from paddy fields.     

节水灌溉对稻田N2O季节排放特征的影响

为了揭示节水灌溉对技术对稻田N2O排放的影响,采用静态暗箱-气相色谱法对稻田N2O排放进行了田间原位观测,分析了节水灌溉对稻田N2O季节排放特征的影响。结果表明,水稻全生育期节水灌溉稻田N2O平均排放通量为41.84 μg/(m2 ?h),较淹水灌溉稻田N2O平均排放通量增加了33.3%;节水灌溉稻田N2O排放总量为119.86 mg/m2,比淹水灌溉稻田显著增加了17.8%;节水灌溉稻田N2O排放通量呈现明显的季节变化规律,有两次较大的排放峰值,峰值主要出现在施肥后1周左右;节水灌溉稻田土壤的每次脱水过程均不同程度地加剧了N2O排放,复水后N2O排放通量有增有减但变幅不大,而淹水灌溉稻田在黄熟期落干阶段N2O排放出现反弹。由此可见,不同灌溉模式下的稻田土壤水分状况决定了N2O季节排放的差异,与淹水灌溉相比,控制灌溉显著增加了稻田N2O季节排放量。     

Soils and nitrous oxide research

Between 1990 and 2008, Soil Use and Management has published around 42 articles which have dealt with nitrous oxide (N₂O) emissions from soils. The importance of this subject to readers of the journal has increased rapidly in recent years. A substantial number of these papers have appeared in two supplements. These were ‘Soils and the Greenhouse Effect’, vol. 13 (4) and ‘Soils as Carbon Sinks’, vol. 20. The number of annual citations of articles on N₂O in the journal has risen from zero in the early 1990s to 160 per year in 2008. In this article, we have highlighted some of the more important papers on N₂O that have been published by Soil Use and Management, and explain how they have helped advance our understanding of the role that soil management plays in influencing N₂O emissions.     

控制灌溉稻田的甲烷减排效果

为探讨节水灌溉水分调控对稻田甲烷（CH4）排放的影响,寻找节水减排的稻田灌溉模式,依据5a田间原位观测资料,分析控制灌溉稻田CH4排放规律及其减排效果。结果表明,控制灌溉稻田稻季CH4排放量为1.07±0.17 g/m2,较淹水灌溉稻田（6.49±0.17 g/m2）降低83.5%,差别极显著。本研究得到的中国东南部稻田稻季和全年CH4排放量均低于已有报道中的中国稻田CH4排放量,其中控制灌溉稻田全年CH4排放量低于世界大部分地区稻田。根据本研究结果估算中国稻田CH4排放总量为2.06 Tg/a,大面积推广控制灌溉后,中国稻田CH4排放量还将进一步下降。控制灌溉模式显著影响水稻全生育期稻田CH4排放通量的变化,削峰效果显著。控制灌溉稻田CH4排放通量在返青期至分蘖中期（移栽后18 d内）逐渐上升至最大值,然后逐渐减小,从水稻分蘖后期（移栽后21 d）开始至生育期结束均维持在较低水平。控制灌溉稻田CH4排放通量峰值为3.69 mg/m2·h,较淹水灌溉稻田降低69.0%。在持续降雨的作用下,控制灌溉和淹水灌溉模式下稻田CH4排放通量均呈现下降趋势。控制灌溉模式的土壤水分调控,使稻田经历一系列的脱水过程,改变了根层土壤的水气状况,减小了稻田CH4排放。控制灌溉模式在水稻全生育期的应用可显著地减少稻田CH4排放。     

The contribution of agricultural practices to nitrous oxide emissions in semi-arid Mali

The yield and flux of nitrous oxide (N₂O) emitted from continuous cereals (with and without urea), legumes/cereal in rotation and cereal/legume in rotation all with or without organic manure was monitored from January 2004 to February 2005. All treatments except continuous cereals had phosphate added. The cereal grown July–October in 2003 and 2004 was pearl millet ( Pennisetum glaucum) and the legume was a bean ( Phaseolus vulgaris ). The 10 m × 10 m plots were established in a semi-arid climate in Mali. The addition of organic manure and both inorganic fertilizers increased yield and N₂O emissions. Continuous cereals treated with both organic manure and urea emitted significantly less N₂O (882 g N/ha per year) than plots receiving no organic manure(1535 g N/ha per year). Growing N-fixing crops in rotation did not significantly increase N₂O emissions. This study supports the new practice of growing cereal and legumes in rotation as an environmentally sustainable system in semi-arid Mali.     

Carbon-iron coupling reduced N2O emissions via promoting the conversion to N2 in paddy soils

The influence of redox reactions involving carbon-iron coupling (organic carbon and iron oxides) on nitrous oxide (N₂O) production in paddy soils remains poorly understood. In this study, two microcosm experiments were conducted to investigate the effects of carbon-iron coupling on N₂O emissions, and the underlying mechanisms were verified using quantitative denitrification functional genes (nirS, nirK, nosZI and nosZII) and high-throughput sequencing. The results showed that ferrihydrite (iron) significantly promoted N₂O-N emissions (p < 0.05) after adding ammonium nitrogen, while glucose (carbon) significantly inhibited N₂O-N emissions (p < 0.05). Carbon-iron coupling significantly decreased N₂O-N emissions (p < 0.05) but did not affect soil total nitrogen loss and increased nitrogen (N₂) emissions. After adding high concentrations of acetylene (10% C₂H₂), the N₂O-N emissions from carbon-iron coupling treatment increased significantly from 6.4 to 11.9 mg N kg⁻¹ (p < 0.05), which confirmed that the carbon-iron coupling reduced the N₂O emissions by promoting the conversion of N₂O to N₂. The mechanisms behind carbon-iron coupling promoting complete denitrification and reducing N₂O emissions were attributed to glucose promoting iron reduction and carbon-iron coupling enhancing the abundance of nosZI (42.7%) and nosZII (16.6%).     

Effects of disturbance and glucose addition on nitrous oxide and carbon dioxide emissions from a paddy soil

The effects of disturbance and glucose addition on N₂O and CO₂ emissions from a paddy soil at 45% WFPS (water-filled pore space) and at 25 °C were determined. During a 45-day incubation, disturbances with and without glucose addition were imposed 0, 1, 3, and 5 times. The total amount of glucose added to soil with 1, 3, and 5 disturbances was equal (0.6% of oven-dry soil basis). Strong nitrification occurred in the paddy soil during the incubation. Disturbance alone did not influence N₂O and CO₂ emissions significantly, but disturbance with glucose addition did (P < 0.01). A flush of N₂O as well as CO₂ was always observed following disturbance with glucose addition. The discrepancy in N₂O emission between disturbance alone and disturbance with glucose addition was ascribed to the different magnitude of denitrification and/or heterotrophic nitrification. Greater cumulative emission of N₂O was observed in the treatment of three disturbance times with glucose addition (4.3 mg N kg⁻¹ soil), compared with five disturbances with glucose addition (2.5 mg N kg⁻¹ soil) and one disturbance with glucose addition (2.5 mg N kg⁻¹ soil). Cumulative CO₂ emission was significant larger in one and three disturbances with glucose addition than that five disturbance with glucose addition. Supplies of available organic C appear to be a critical factor controlling denitrification and/or heterotrophic nitrification processes and N₂O emission under relatively low moisture conditions, i.e. 45% WFPS.