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981.
W.K. Ma A. Bedard-Haughn S.D. Siciliano R.E. Farrell 《Soil biology & biochemistry》2008,40(5):1114-1123
The link between differences in the community composition of nitrifiers and denitrifiers to differences in the emission of nitrous oxide (N2O) from soils remains unclear. Nitrifier and denitrifier community composition, abundance and N2O emission activity were determined for two common landscapes characteristic of the North American “prairie pothole region”: cultivated wetlands (CW) vs. uncultivated wetlands (UW). The hypotheses of this study were: (1) landscape selects for different nitrifier and denitrifier communities, (2) denitrification was the dominant N2O emitting process, and (3) a relationship exists between nitrifier and denitrifier community composition, their abundance, and N2O emission. Comparisons were made among soils from three CW and three UW at the St. Denis National Wildlife Area. Denaturing gradient gel electrophoresis was used to compare community composition, and quantitative polymerase chain reaction was used to estimate community size. Incubation experiments on re-packed soil cores with 15N-labeled nitrate were performed to assess the relative contributions of nitrification and denitrification to total N2O emission. Results indicate: (1) nitrification was the primary source of N2O emission, (2) cultivation increased nitrifier abundance but decreased nitrifier richness, (3) denitrifier abundance was not affected by cultivation but richness was increased by cultivation, and (4) differences in nitrifier and denitrifier communities composition and abundance between land-use and landform did not correspond to differences in N2O emission. 相似文献
982.
以三江平原沼泽湿地不同开垦年限(1987年、1993年开垦)的旱田(种植方式为大豆-冬闲)为研究对象,探讨了种植年限,降雨、土壤湿度以及植物参与对旱田N2O排放的影响。结果表明,种植年限越长,N2O排放量越高,1987年开垦的旱田N2O排放量显著高于1993年开垦的,这与土壤的理化性质有关;土壤有机碳和总氮含量随种植年限的增加而逐渐降低,而δ^15N随种植年限呈线性升高。在大豆生长季内,两种种植年限的旱田N2O通量具有相同的季节变化趋势,而降水条件是控制这一变化趋势的主要因素,N2O排放通量与观测日前6天的加权平均降水量呈线性正相关,与土壤体积含水量呈多项式正相关。另外,植物的参与降低了旱田土壤N2O的排放。 相似文献
983.
984.
利用FACE (free-air carbon dioxide enrichment)平台,采用静态暗箱-气相色谱法,研究了大气CO2浓度升高对稻田土壤CO2通过土壤-大气(土气)和植被-大气(植气)界面排放的影响.在整个水稻生长季中,土气界面CO2排放通量与土壤表面水层深度指数负相关,且在中期烤田和收获前排水阶段出现较大值;而植气界面CO2排放通量与根系生物量的变化趋势基本一致.在低氮(N 125 kg/hm2)和常氮(N 250 kg/hm2)水平上,高浓度CO2(对照大气CO2浓度+200 μmol/mol)有提高水稻生物量、降低土气和植气界面CO2累积排放量的趋势.在水稻的拔节、抽穗和成熟期,较高的施氮量显著增加水稻地上部分生物量,促进植气界面CO2的排放.研究结果表明,未来大气CO2浓度升高的环境下,稻田生态系统有增加CO2的固定(增加水稻生物量),减少CO2的排放(土气和植气界面CO2的排放)的趋势,可能发挥着碳汇的作用. 相似文献
985.
《Communications in Soil Science and Plant Analysis》2012,43(14):1763-1777
A 56-day aerobic incubation experiment was performed with 15-nitrogen (N) tracer techniques after application of wheat straw to investigate nitrate-N (NO3-N) immobilization in a typical intensively managed calcareous Fluvaquent soil. The dynamics of concentration and isotopic abundance of soil N pools and nitrous oxide (N2O) emission were determined. As the amount of straw increased, the concentration and isotopic abundance of total soil organic N and newly formed labeled particulate organic matter (POM-N) increased while NO3-N decreased. When 15NO3-N was applied combined with a large amount of straw at 5000 mg carbon (C) kg?1 only 1.1 ± 0.4 mg kg?1 NO3-N remained on day 56. The soil microbial biomass N (SMBN) concentration and newly formed labeled SMBN increased significantly (P < 0.05) with increasing amount of straw. Total N2O-N emissions were at levels of only micrograms kg?1 soil. The results indicate that application of straw can promote the immobilization of excessive nitrate with little emission of N2O. 相似文献
986.
施肥方式对冬小麦季紫色土N2O排放特征的影响 总被引:6,自引:2,他引:6
利用紫色土养分循环长期定位施肥试验平台,通过静态箱-气相色谱法,于2012年11月至2013年5月,研究了单施氮肥(N)、猪厩肥(OM)、常规氮磷钾肥(NPK)、猪厩肥配施氮磷钾肥(OMNPK)、秸秆还田配施氮磷钾肥(CRNPK)及对照不施肥(NF)6种施肥方式下,紫色土冬小麦季土壤N2O的排放特征。结果表明,在相同施氮水平[130 kg(N)·hm-2]下,施肥方式对N2O排放量有显著影响(P0.05)。N、OM、NPK、OMNPK和CRNPK处理下,土壤N2O排放量[kg(N)·hm-2]分别为0.38、0.36、0.29、0.33和0.19,N2O排放系数分别为0.25%、0.23%、0.18%、0.21%和0.10%。NF的土壤N2O排放量为0.06 kg(N)·hm-2。土壤无机氮含量(NO3--N和NH4+-N)是N2O排放的主要影响因子,降雨能有效激发N2O排放。基于小麦产量评价不同施肥方式下的N2O排放,结果表明,N、OM、NPK、OMNPK和CRNPK单位小麦产量N2O的GWP值[yield-scaled GWP,kg(CO2 eq)·t-1]分别为132.57、45.70、49.07、48.92和26.41。CRNPK的小麦产量与6种施肥方式中获得最大产量的OM间没有显著差异,但显著高于其他处理。而且,CRNPK的yield-scaled GWP比紫色土地区冬小麦种植中常规施肥方式(NPK)显著减少46%,并显著低于其他4种施肥方式。可见,秸秆还田配施氮磷钾肥在保证小麦产量的同时,能有效减少因施肥引发的N2O排放,可作为紫色土地区推荐的最佳施肥措施。 相似文献
987.
生物质炭还田对稻田甲烷的减排效果 总被引:8,自引:6,他引:8
为探讨不同生物质炭类型、输入量、还田时间和还田深度等因素作用下的CH4排放特征,采用静态箱-气相色谱法,通过向稻田土壤中施用3种类型的生物质炭(稻秆炭、麦秆炭、竹炭),开展了水稻一个生长周期的室内观测试验。结果表明,3种类型的生物质炭输入后,对比空白处理,水稻产量显著性增加(P<0.05),其中竹炭处理每盆实粒质量高达18.12 g,说明施用生物质炭可增加水稻产量;竹炭施用后稻田土壤CH4排放通量(80 mg/m2 h)显著低于稻杆炭和麦杆炭处理(P<0.05),而稻杆炭和麦杆炭处理无显著性差异(P>0.05),但都显著高于空白处理(P<0.05),说明施用生物质炭可有效减少CH4排放。CH4排放通量与生物质炭用量负相关,CH4的排放通量随着生物质炭用量的逐渐增加而降低。同时,水稻移植前施用竹炭CH4排放通量(56.6 mg/m2 h)低于空白(96 mg/m2 h)及水稻成活前后(73.4和76.6 mg/m2 h),但无显著性差异(P>0.05),这与土壤氧化还原电位(Eh)变化相一致,说明生物质炭施用时间对稻田土壤CH4排放通量影响不大。此外,不同竹炭还田深度下的土壤CH4排放通量顺序为:中部输入(15 cm处输入)<表层输入(5 cm处输入)<深部输入(25 cm处输入)<空白(不输入生物质炭),说明生物质炭中部输入更适用微生物生长和CH4气体减排。该研究可为太湖地区苕溪流域稻田增汇和温室气体减排提供参考。 相似文献
988.
The influence of NH4+ on microbial CH4 oxidation is still poorly understood. Therefore, the influence of NH4Cl and (NH4)2SO4 on CH4 oxidation was studied in soils at the different stages of the induction of enhanced methanotrophic activity. After a brief peak in the methanotrophic activity, a steady state was observed in which NH4+ inhibited CH4 oxidation at low CH4 concentrations, and stimulated CH4 oxidation at high concentrations. Chloride did not strongly inhibit CH4 oxidation during this phase. During a second phase methanotrophic activity increased again. Ammonium no longer stimulated CH4 oxidation, and Cl− became an important source of uncompetitive inhibition. It was hypothesized that type I methanotrophs dominated during the first, soil-N-dependent phase while N2-fixing type II methanotrophs dominated the second, soil-N-independent phase. 相似文献
989.
990.
Barbara Chaves Stefaan De Neve Maria del Carmen Lillo Cabrera Pascal Boeckx Oswald Van Cleemput Georges Hofman 《Biology and Fertility of Soils》2005,41(6):411-418
Manipulating the N release from high-N crop residues by simultaneous mixing of these residues with organic biological waste (OBW) materials seems to be a possible method to reduce NO3– leaching. The aim of this study was to examine whether the incorporation of OBW materials together with a high-N crop residue (celery) had also an effect on N2O emission from horticultural soil under short-term and optimised laboratory conditions. A sandy loam soil and celery residues were mixed with different OBW materials and brought into PVC tubes at 80% water-filled pore space and 15°C. Every 2.5 h, a gas sample was taken and analysed by gas chromatography for its N2O concentration. The soil amended with only celery residues had a cumulative N2O emission of 9.6 mg N kg–1 soil in 50 h. When the celery residues were mixed with an OBW material, the N2O emission was each time lower than the emission from the celery-only treatment (between 3.8 and 5.9 mg N kg–1 soil during maximum 77 h), except with paper sludge (17.2 mg N kg–1 soil in 100 h). The higher N2O emission from the paper sludge treatment was probably due to its unusually low C:N ratio. Straw, green waste compost 1 (GWC1) and 2 (GWC2), saw dust, and tannic acid reduced the N2O emission of the celery treatment by 40 to 60%. Although the N2O reduction potential can be expected to be lower and with differing dynamics under field conditions, this study indicates that apart from reducing NO3– leaching, OBW application may at the same time reduce N2O emissions after incorporation of high-N crop residues. 相似文献