种植杂交稻对甲烷排放的影响及评价

早、中、晚稻三季24h稻田甲烷监测结果表明,种植杂交稻没有明显增进福田甲烷排放的作用．甲烷释放总量在3个种植季节中,除连作晚稻的杂交稻田比常规稻田高11．6％外,早稻、单季稻杂交稻田分别低于常规稻田6．4％和8．9％．稻田甲烷每周日平均释放量在水稻生长前期（移栽后5～7周）杂交稻高于常规稻,孕穗至收获期杂交稻低于常规稻．温度对甲烷释放影响十分明显．在不同水稻种植季节,稻田甲烷释放模式各不相同．经测定,杂交稻田的土壤产甲烷细菌数量及土壤产甲烷潜力明显高于常规稻田,其中产甲烷细菌数可相差数倍至2个数量级．试验结果还表明,种植水稻明显增加了稻田甲烷排放量,与侵水稻田相比．植稻田甲烷排放量增加了41．4％．     

华中地区水旱轮作模式下水稻季施氮肥对油菜季施氮肥土壤N2O排放的影响

设置了水稻季与油菜季均不施用氮肥(N0-0);水稻季施用氮肥150 kg·hm-2(以N计,下同),油菜季不施用氮肥(N150-0);水稻季与油菜季均施用氮肥150 kg·hm-2(N150-150);水稻季不施用氮肥,油菜季施用氮肥150 kg·hm-2(N0-150)4种施肥处理,采用静态箱/气相色谱法对旱作油菜季N_2O的排放进行了原位观测(2016年9月—2017年4月),研究了华中地区水旱轮作模式下水稻季施肥对油菜季土壤N_2O排放的影响.结果表明,油菜季N_2O排放主要集中在施基肥后1周内.N0-0、N150-0、N150-150和N0-150处理N_2O排放通量变化范围分别为-10.81~181.26、-20.48~95.61、-8.87~638.56和-21.76~827.86μg·m-2·h-1,平均排放通量分别为4.58、3.89、21.06和27.24μg·m-2·h-1,N_2O累积排放量分别为0.20、0.17、0.92和1.19 kg·hm-2,施氮肥处理(N150-150和N0-150)N_2O排放量显著高于不施氮肥处理(N0-0、N150-0)(p0.05).N150-150和N0-150处理N_2O排放通量与土壤孔隙充水率(WFPS)具有显著正相关关系(p0.05);N150-150和N0-150处理N_2O排放通量与土壤可溶性有机氮(DON)和无机氮(NO-3-N和NH+4-N)具有显著正相关关系(p0.01).以上结果表明,油菜季N_2O排放与稻季施用氮肥无关,施氮肥对土壤活性氮含量的影响是导致N_2O排放差异的主要原因,而土壤孔隙充水率也是影响油菜季N_2O排放的重要环境因子.     

Effect of different fertilizers on methane emission from a paddy field of Zhejiang, China

ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｃｒｅａｓｅｄａｇｒｉｃｕｌｔｕｒａｌｐｒｏｄｕｃｔｉｖｉｔｙｏｖｅｒｔｈｅｐａｓｔ５０—１００ｙｅａｒｓｈａｓｌｅｄｔｏｉｎｃｒｅａｓｅｄａｔｍｏｓｐｈｅｒｉｃｃｏｎｃｅｎｔｒａｔｉｏｎｓｏｆＣＯ２，ＣＨ４ａｎｄＮ２Ｏ．Ｔｈｅｓｅｇａｓｅｓ，ａｌｏｎｇｗｉｔｈａｄｄｉｔｉｏｎｔｒａｃｅｇａｓｓｐｅｃｉｅｓ（ｇｒｅｅｎｈｏｕｓｅｇａｓｅｓ）ａｒｅｃａｕｓｉｎｇａｎｉｎｃｒｅａｓｅｉｎｇｌｏｂａｌｔｅｍｐｅｒａｔｕｒｅｓａｎｄｏｚｏｎｅｄｅｐｌｅｔｉｏｎ（Ａｓｅｌｍａｎ…     

Effect of elevated tropospheric ozone on methane and nitrous oxide emission from rice soil in north India

Physiological changes in crop plants in response to the elevated tropospheric ozone (O₃) may alter N and C cycles in soil. This may also affect the atmosphere-biosphere exchange of radiatively important greenhouse gases (GHGs), e.g. methane (CH₄) and nitrous oxide (N₂O) from soil. A study was carried out during July to November of 2007 and 2008 in the experimental farm of Indian Agricultural Research Institute, New Delhi to assess the effects of elevated tropospheric ozone on methane and nitrous oxide emissions from rice (Oryza sativa L.) soil. Rice crop was grown in open top chambers (OTC) under elevated ozone (EO), non-filtered air (NF), charcoal filtered air (CF) and ambient air (AA). Seasonal mean concentrations of O₃ were 4.3 ± 0.9, 26.2 ± 1.9, 59.1 ± 4.2 and 27.5 ± 2.3 ppb during year 2007 and 5.9 ± 1.1, 37.2 ± 2.5, 69.7 ± 3.9 and 39.2 ± 1.8 ppb during year 2008 for treatments CF, NF, EO and AA, respectively. Cumulative seasonal CH₄ emission reduced by 29.7% and 40.4% under the elevated ozone (EO) compared to the non-filtered air (NF), whereas the emission increased by 21.5% and 16.7% in the charcoal filtered air (CF) in 2007 and 2008, respectively. Cumulative seasonal emission of N₂O ranged from 47.8 mg m⁻² in elevated ozone to 54.6 mg m⁻² in charcoal filtered air in 2007 and from 46.4 to 62.1 mg m⁻² in 2008. Elevated ozone reduced grain yield by 11.3% and 12.4% in 2007 and 2008, respectively. Global warming potential (GWP) per unit of rice yield was the least under elevated ozone levels. Dissolved organic C content of soil was lowest under the elevated ozone treatment. Decrease in availability of substrate i.e., dissolved organic C under elevated ozone resulted in a decline in GHG emissions. Filtration of ozone from ambient air increased grain yield and growth parameters of rice and emission of GHGs.     

Effect of application of ammonium thiosulphate on production and emission of methane in a tropical rice soil

Agricultural sources of atmospheric methane include flooded rice (Oryza sativa L.) paddies. However, certain soil nutrient management and cultural practices offer opportunities to reduce methane emissions. The effect of application of ammonium thiosulphate, a potential source of nitrogen and sulphur and also an inhibitor of nitrification and urease on methane production and emission from flooded alluvial (Typic Haplaquept) rice soil in India, was examined. Methane production and emission from control and urea-amended soil samples were almost identical. Application of ammonium thiosulphate to laboratory-incubated flooded soil (30 and 60 μg N g⁻¹ soil) and flooded rice fields (45.6 and 60 kg N ha⁻¹) effected a distinct inhibition of methane production and emission. Ammonium thiosulphate stimulated the population of sulphate-reducing bacteria (SRB) to a greater extent at 60 μg N g⁻¹ soil than at 30 μg N g⁻¹ soil. In ammonium thiosulphate-applied rice field plots, mean methane efflux decreased by about 38 and 60% at 45.6 and 60 kg N ha⁻¹, respectively, over that of control. Inhibition of methane production by ammonium thiosulphate is, at least in part, due to the stimulation of SRB. Results suggest the mitigation potential of ammonium thiosulphate on methane emission from flooded rice paddies.     

Methane emission in a rice field of Thailand

ＭｅｔｈａｎｅｅｍｉｓｓｉｏｎｉｎａｒｉｃｅｆｉｅｌｄｏｆＴｈａｉｌａｎｄ￥ＲｏｎｇＸｉａｎｇ；Ｃｈｕｅｎ－ＨｏｗＮｇ（ＥｎｖｉｒｏｎｍｅｎｔａｌＥｎｇｉｎｅｅｒｉｎｇＰｒｏｇｒａｍ，ＳｃｈｏｏｌｏｆＥｎｖｉｒｏｎｍｅｎｔ，ＲｅｓｏｕｒｃｅｓａｎｄＤ...     

Characteristics of methane emission from wetland rice–duck complex ecosystem

The effects of rice–duck complex ecosystem on methane emission were investigated through two experimental approaches of plot and field experiments in subtropical region of China. Compared with conventional rice fields, the rice–duck ecological planting and breeding model significantly decreased the methane emission from paddy fields. Methane emission flux from rice–duck complex ecosystem presented distinct diurnal and seasonal variations. The diurnal variation in methane emission flux was basically consistent with daily temperature change, and methane emission flux reached a peak from 12 noon to 2 p.m. But the seasonal variation patterns of methane emission flux were not completely consistent between early rice and late rice. The peak of methane emission flux for early rice and late rice, respectively, appeared in the young panicle differentiation stage and the full tillering stage. Moreover, the seasonal fluctuation range of methane emission flux from early rice was smaller than that from late rice, and the total amount of methane emission from late rice also significantly higher than that from early rice. These results clearly indicate the possibility of reducing methane emission under wetland rice–duck complex ecosystem.     

川中丘陵地区冬水田甲烷排放特征研究

以川中丘陵地区典型冬水田为对象,设置了有水稻常规施肥(RF)、无水稻常规施肥(NP)、有水稻无氮肥(NN)3种处理,以静态暗箱-气相色谱法对甲烷(CH_4)排放进行了原位观测.结果表明,RF、NP和NN处理下CH_4排放通量分别为-0.0042~18.29、0.03~16.78和0.10~26.76mg·m~(-2)·h~(-1),平均排放通量分别为10.22、4.25和14.15 mg·m~(-2)·h~(-1)(以每平方米每小时消耗/产生的C量(mg)计),水稻生长季是主要排放期,但休闲季CH_4排放量仍占全年CH_4总排放量的14%.没有水稻处理的CH_4排放量显著低于有水稻处理(p0.01);而不施氮肥处理的CH_4排放量显著高于施肥处理(p0.01).CH_4排放通量与5 cm深土壤温度呈显著正相关(p0.01),随着温度的升高,甲烷排放量呈指数增加.CH_4排放通量与1~4 cm的稻田水深呈显著负相关(p0.01),随着水深的增加,甲烷的排放呈指数迅速下降;而与4~8 cm的稻田水深无相关性,甲烷的排放也变化缓慢.由此表明,土壤温度和水深在很大程度上调控着CH_4的排放.此外,研究结果也显示将冬水田休闲期改为旱作可减少CH_4排放,对环境有利.     

Ammonia volatilization losses and balance from urea applied to rice on a paddy soil

Ammonia volatilization loss and 15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4+-N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%-38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. 15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency.     

碳、氮物质对水稻田土壤甲烷氧化活性影响的研究

研究了碳素和氮素物质对黄松田土壤中甲烷氧化菌种群及其甲烷氧化活性的影响，结果表明，加入不同碳素或氮素物质对黄松田土中甲烷氧化菌种群的数量变化无显著性影响，但对土壤氧化外源甲烷烷尖性却具有显著性影响，且不同浓度的同一物质对黄松田土壤氧化外源甲烷速率的影响也不相同，甲烷氧化代谢途径中的中间产物（甲醇和甲酸）较非甲烷氧化代谢途径中的中间产物和能促进土壤产甲烷菌产甲烷活性的碳源物质（酵母膏，葡萄糖和乙酸）可更强烈地抑制土壤氧化外源甲烷的活性，有机氮素物质对黄松田土的甲烷氧化速率的影响要较无机氮素质质弱，在无机氮素物质中，硝酸盐对土壤氧化外源甲烷活性的抑制强度要强于铵盐类物质，NH3要比NH^ 4对甲烷氧化菌的甲烷氧化活性具有更强的抑制作用，一旦黄松田土的甲烷氧化活性受到碳，氮物质的抑制，恢复其氧化外源甲烷活性就需要较长时间，且受到抑制的过程越,恢复所需时间也越长。     

Geological emission of methane from the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China

A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p...     

Modeling the impact of mitigation options on methane abatement from rice fields

The enhanced concentration of methane (CH₄) in the atmosphere is significantly responsible for the ominous threat of global warming. Rice (Oryza) paddies are one of the largest anthropogenic sources of atmospheric CH₄. Abatement strategies for mitigating CH₄ emissions from rice fields offer an avenue to reduce the global atmospheric burden of methane and hence the associated menace of climate change. Projections on population growth suggest that world rice production must increase to meet the population’s food energy demand. In this scenario, those mitigation options are advocated which address both the objectives of methane mitigation and increased production of rice simultaneously. In this paper, we have formulated a nonlinear mathematical model to investigate the effectiveness and limitations of such options in reducing and stabilizing the atmospheric concentration of CH₄ while increasing rice yield. In modeling process, it is assumed that implementation rate of mitigation options is proportional to the enhanced concentration of atmospheric CH₄ due to rice fields. Model analysis reveals that implementation of mitigation options not always provides “win-win” outcome. Conditions under which these options reduce and stabilize CH₄ emission from rice fields have been derived. These conditions are useful in devising strategies for effective abatement of CH₄ emission from rice fields along with sustainable increase in rice yield. The analysis also shows that CH₄ abatement highly depends on efficiencies of mitigation options to mitigate CH₄ emission and improve rice production as well as on the implementation rate of mitigation options. Numerical simulation is carried out to verify theoretical findings.     

Ammonia volatilization losses and 15N balance from urea applied to rice on a paddy soil

Ammonia volatilization loss and ^15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4^＋-N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%-38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. ^15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency.     

庭院垃圾对填埋场甲烷的减量化研究

将熟化时间为24个月和2个月的庭院垃圾分别用于建设0.9 m厚的1#和2#两个生物覆盖层单元,并进行了为期15个月的野外试验,以验证庭院垃圾能否作为生物覆盖层材料用于减少垃圾填埋场甲烷的排放,以及利用同位素和质量守恒方法量化生物覆盖层对垃圾填埋场甲烷的氧化能力.结果表明,两个生物覆盖层对甲烷的氧化能力在建设初期达到整个观测期的最高值,分别为(141±10)g·m-2·d-1和(197±27)g·m-2·d-1,随后生物覆盖单元的甲烷氧化能力随季节交替降低至18~120 g·m-2·d-1和23~70 g·m-2·d-1.试验的中后期,在两个生物覆盖单元中均观测到明显数量的甲烷产出.试验结果表明24个月和2个月熟化时间的庭院垃圾作为生物覆盖填料,均具有较好的甲烷减量化能力,但所含不稳定有机质在厌氧条件下的降解会造成额外的甲烷释放.除此之外,在利用质量守恒方法量化甲烷氧化率时,忽略非甲烷氧化菌的呼吸作用会高估庭院垃圾对甲烷的减量化能力.     

稻季施用不同尿素品种的氮素径流和淋溶损失

在太湖地区乌栅土上,利用大型原状土柱研究不同尿素品种、施肥量处理在稻季氮素径流和淋溶损失.结果表明,包膜尿素在基施情况下,田面水总氮浓度始终接近对照水平,通过径流损失的可能性很小.尿素处理施肥后2d内田面水氮浓度达最高值,随后急剧下降,施肥与径流产生时间的间隔是决定径流氮排放大小的关键因素,施肥5d后的降雨不易造成大的径流排放,氮径流损失与尿素施用量呈显著正相关.各处理间的氮素淋溶排放无显著差异,在2.66～3.25kgN/hm²之间;淋溶液中NO₃^--N浓度最高为0.83mgN/L,在正常施肥情况下,此类土壤氮的淋溶不会造成地下水NO₃--N的严重污染.     

冬水田转稻麦轮作对小麦生长季温室气体排放的影响

用静态暗箱-气相色谱法测定了川中丘陵地区典型冬水田(RF)及冬水田转稻麦轮作处理(RW)在小麦生长季的温室气体排放通量,并同步测定了土壤温度、水分和可溶态碳氮含量.结果表明,RW在小麦生长季的CH4、生态系统呼吸CO2和N2O平均排放通量分别为0.05、117.01 mg·m-2·h-1(以C计)和77.19μg·m-2·h-1(以N计),而RF相应通量分别为1.43、7.85 mg·m-2·h-1和-0.61μg·m-2·h-1.RW施氮肥后出现N2O的排放峰,其N2O直接排放系数为1.28%.土壤可溶态有机碳含量与CO2通量之间呈显著正相关关系(r=0.342,p0.01),与CH4、N2O的相关关系不显著;硝态氮、可溶态总氮含量与N2O通量的关系为显著正相关,但与CH4通量呈显著负相关.RF的综合增温潜势(以CO2-eq计,下同)为3.03 Mg·hm-2,大于RW(-1.66 Mg·hm-2),暗示冬水田转稻麦轮作会降低生态系统的综合增温效应.     

Influence of season,ventilation strategy,and slurry removal on methane emissions from pig houses

About 60% of the global methane emission is related to anthropogenic activities such as agriculture, fossil fuel use, and waste disposal. A significant part of agricultural methane emissions originates from pig husbandry, with indoor stored pig slurry as the main source. In general, the release of methane from indoor slurry storage can be influenced by availability of oxygen and volatile solids, pH value, substrate temperature, retention time, and presence of inhibiting compounds. Investigations on methane release from a pig house with indoor slurry storage were carried out from October 1999 until February 2001 and from February 2003 until July 2004, respectively. The season, in which the fattening period was accomplished, had a significant influence on the level of the methane emission rate, with increased emissions during summer. However, a clear influence of the indoor temperature – and therefore of the ventilation strategy – on the level of the methane emission rate was only found for mean daily temperatures above 25 °C. Methane emissions were reduced significantly due to complete slurry removal between the fattening periods and subsequent cleaning of the slurry pits.     

Attributes of a hopper-predator community in a rice field

A hopper-predator community in an experimental rice field was observed weekly with regard to information content (H′), formation of a geometric series or the grade of orderly distribution of component taxa (R²), and clumping index (I). These community attributes changed with time in close association with one another, and attained the highest values around the heading time of the rice. Significant correlations were found between the density of prey and that of predators when a certain time-lag was assumed for the increase of predators.     

覆草旱作稻田CH4和N2O的排放

通过田间试验比较水稻覆草旱作常规施氮肥、覆草旱作推荐施氮肥和常规水作水稻全生育期内稻田土壤微量气体的排放.结果表明,旱作稻田N2O排放总量比水作稻田高1.5~3.7倍,在旱作覆草处理中常规施肥N2O排放较推荐施肥高2.4倍.水作稻田CH4排放总量比旱作稻田多5~6倍,而两旱作处理间差异不显著.水作稻田CH4的排放与水稻生育期关系密切,以分蘖盛期的2.2mg/(m2h)为最大;旱作稻田CH4的排放与施氮关系不明显.施氮是影响旱作稻田N2O排放的关键因素,每次施氮后,旱作稻田均会出现剧烈的排放高峰.水稻不同栽培方式的增温潜势的高低顺序为:覆草旱作常规施氮肥>常规水作>覆草旱作推荐施氮肥.     

Effect of dissolved oxygen on methane production from bottom sediment in a eutrophic stratified lake

Clarifying the role of sulfate and dissolved oxygen (DO) in methane production may allow for precise and accurate modeling of methane emissions in eutrophic lakes. We conducted field observations of sulfate, methane, and DO concentrations in Lake Abashiri, a typical brackish and eutrophic lake in a cold region, to develop a DO-based method for quantitively estimating methane production in a eutrophic lake and analyzed the results. We found that sulfate concentrations decreased rapidly from 900.0 mg/L in water overlying the sediments to nearly 0.0 mg/L in the bottom sediment. Methane production was almost uniform across sediment depths of 0.05 to 0.25 m, ranging from 1400 to 1800 µmol/m²/day. Also, methane production was found to be a function of DO concentrations in water overlying the bottom and could be modeled by a logistic function: constant production at 1,400 µmol/m²/day for DO concentrations of 0.0 to 3.0 mg/L, rapidly decreasing to 0 µmol/m²/day for DO concentrations of 3.0 to 6.0 mg/L. This methane model was verified using a simple one-dimensional numerical model that showed good agreement with field observations. Our results thus suggest that the proposed methane model reduces uncertainty in estimating methane production in a eutrophic lake.