共查询到20条相似文献,搜索用时 31 毫秒
1.
Eleanor E. Campbell Jane M. F. Johnson Virginia L. Jin R. Michael Lehman Shannon L. Osborne Gary E. Varvel Keith Paustian 《Bioenergy Research》2014,7(2):491-502
Harvesting crop residue needs to be managed to protect agroecosystem health and productivity. DAYCENT, a process-based modeling tool, may be suited to accommodate region-specific factors and provide regional predictions for a broad array of agroecosystem impacts associated with corn stover harvest. Grain yield, soil C, and N2O emission data collected at Corn Stover Regional Partnership experimental sites were used to test DAYCENT performance modeling the impacts of corn stover removal. DAYCENT estimations of stover yields were correlated and reasonably accurate (adjusted r 2?=?0.53, slope?=?1.18, p?<<?0.001, intercept?=?0.36, p?=?0.11). Measured and simulated average grain yields across sites did not differ as a function of residue removal, but the model tended to underestimate average measured grain yields. Modeled and measured soil organic carbon (SOC) change for all sites were correlated (adjusted r 2?=?0.54, p?<<?0.001), but DAYCENT overestimated SOC loss with conventional tillage. Simulated and measured SOC change did not vary by residue removal rate. DAYCENT simulated annual N2O flux more accurately at low rates (≤2-kg N2O-N ha?1 year?1) but underestimated when emission rates were >3-kg N2O-N ha?1 year?1. Overall, DAYCENT performed well at simulating stover yields and low N2O emission rates, reasonably well when simulating the effects of management practices on average grain yields and SOC change, and poorly when estimating high N2O emissions. These biases should be considered when DAYCENT is used as a decision support tool for recommending sustainable corn stover removal practices to advance bioenergy industry based on corn stover feedstock material. 相似文献
2.
Soil moisture effects on gross nitrification differ between adjacent grassland and forested soils in central Alberta, Canada 总被引:3,自引:0,他引:3
Yi Cheng Zu-cong Cai Jin-bo Zhang Man Lang Bruno Mary Scott X. Chang 《Plant and Soil》2012,352(1-2):289-301
Background and aims
Changes in soil moisture availability seasonally and as a result of climatic variability would influence soil nitrogen (N) cycling in different land use systems. This study aimed to understand mechanisms of soil moisture availability on gross N transformation rates.Methods
A laboratory incubation experiment was conducted to evaluate the effects of soil moisture content (65 vs. 100% water holding capacity, WHC) on gross N transformation rates using the 15N tracing technique (calculated by the numerical model FLUAZ) in adjacent grassland and forest soils in central Alberta, Canada.Results
Gross N mineralization and gross NH 4 + immobilization rates were not influenced by soil moisture content for both soils. Gross nitrification rates were greater at 100 than at 65% WHC only in the forest soil. Denitrification rates during the 9 days of incubation were 2.47 and 4.91 mg N kg-1 soil d-1 in the grassland and forest soils, respectively, at 100% WHC, but were not different from zero at 65% WHC. In the forest soil, both the ratio of gross nitrification to gross NH 4 + immobilization rates (N/IA) and cumulative N2O emission were lower in the 65 than in the 100% WHC treatment, while in the grassland soil, the N/IA ratio was similar between the two soil moisture content treatments but cumulative N2O emission was lower at 65% WHC.Conclusions
The effect of soil moisture content on gross nitrification rates differ between forest and grassland soils and decreasing soil moisture content from 100 to 65% WHC reduced N2O emissions in both soils. 相似文献3.
Nitrous oxide emissions and nitrate leaching from a rain-fed wheat-maize rotation in the Sichuan Basin, China 总被引:3,自引:0,他引:3
Minghua Zhou Bo Zhu Klaus Butterbach-Bahl Xunhua Zheng Tao Wang Yanqiang Wang 《Plant and Soil》2013,362(1-2):149-159
Aims
A 3-year field experiment (October 2004–October 2007) was conducted to quantify N2O fluxes and determine the regulating factors from rain-fed, N fertilized wheat-maize rotation in the Sichuan Basin, China.Methods
Static chamber-GC techniques were used to measure soil N2O fluxes in three treatments (three replicates per treatment): CK (no fertilizer); N150 (300 kg N fertilizer ha?1 yr?1 or 150 kg N?ha?1 per crop); N250 (500 kg N fertilizer ha?1 yr?1 kg or 250 kg N?ha?1 per crop). Nitrate (NO 3 ? ) leaching losses were measured at nearby sites using free-drained lysimeters.Results
The annual N2O fluxes from the N fertilized treatments were in the range of 1.9 to 6.7 kg N?ha?1 yr?1 corresponding to an N2O emission factor ranging from 0.12 % to 1.06 % (mean value: 0.61 %). The relationship between monthly soil N2O fluxes and NO 3 - leaching losses can be described by a significant exponential decaying function.Conclusions
The N2O emission factor obtained in our study was somewhat lower than the current IPCC default emission factor (1 %). Nitrate leaching, through removal of topsoil NO 3 ? , is an underrated regulating factor of soil N2O fluxes from cropland, especially in the regions where high NO 3 - leaching losses occur. 相似文献4.
京郊典型设施蔬菜地土壤N_2O排放特征 总被引:10,自引:0,他引:10
利用静态暗箱-气相色谱法对北京郊区设施蔬菜地典型种植模式(番茄-白菜-生菜)下土壤N2O排放特征进行了周年(2012年2月22日—2013年2月23日)观测,探讨了不同处理下(即不施氮肥处理(CK)、农民习惯施肥处理(FP)、减氮优化施肥处理(OPT)和减氮优化施肥+硝化抑制剂处理(OPT+DCD))N2O排放特征及土壤温度、土壤湿度、土壤无机氮含量对土壤N2O排放的影响。结果表明:每次施肥+灌溉之后设施蔬菜地会出现明显的N2O排放高峰,持续时间一般为3—5 d。不同处理N2O排放通量变化范围在-0.21—14.26 mg N2O m-2h-1,平均排放通量0.03—0.36 mg N2O m-2h-1。整个蔬菜生长季各处理N2O排放与土壤孔隙含水率(WFPS)均表现出极显著的正相关关系(P0.01);不施氮处理5 cm深度土壤温度与N2O排放通量呈现显著的正相关关系(P0.05);各处理N2O排放与土壤表层硝态氮含量具有较一致变化趋势。不同处理下N2O年度排放总量差异显著,依次顺序为FP((20.66±0.91)kg N/hm2)OPT((12.79±1.33)kg N/hm2)OPT+DCD((8.03±0.37)kg N/hm2)。与FP处理相比,OPT处理和OPT+DCD处理N2O年排放总量分别减少了38.09%和61.13%。各处理N2O排放系数介于0.36%—0.77%,低于IPCC 1.0%的推荐值。在目前的管理措施下,合理减少施氮量和添加硝化抑制剂是减少设施蔬菜地N2O排放量的有效途径。 相似文献
5.
Eugenio Díaz-Pinés Andreas Schindlbacher Marina Godino Barbara Kitzler Robert Jandl Sophie Zechmeister-Boltenstern Agustín Rubio 《Plant and Soil》2014,384(1-2):243-257
Background and Aims
Tree species composition shifts can alter soil CO2 and N2O effluxes. We quantified the soil CO2 and N2O efflux rates and temperature sensitivity from Pyrenean oak, Scots pine and mixed stands in Central Spain to assess the effects of a potential expansion of oak forests.Methods
Soil CO2 and N2O effluxes were measured from topsoil samples by lab incubation from 5 to 25 °C. Soil microbial biomass and community composition were assessed.Results
Pine stands showed highest soil CO2 efflux, followed by mixed and oak forests (up to 277, 245 and 145 mg CO2-C m?2 h?1, respectively). Despite contrasting soil microbial community composition (more fungi and less actinomycetes in pine plots), carbon decomposability and temperature sensitivity of the soil CO2 efflux remain constant among tree species. Soil N2O efflux rates and its temperature sensitivity was markedly higher in oak stands than in pine stands (70 vs. 27 μg N2O-N m?2 h?1, Q10, 4.5 vs. 2.5).Conclusions
Conversion of pine to oak forests in the region will likely decrease soil CO2 effluxes due to decreasing SOC contents on the long run and will likely enhance soil N2O effluxes. Our results present only a seasonal snapshot and need to be confirmed in the field. 相似文献6.
Liebig’s law of the minimum applied to a greenhouse gas: alleviation of P-limitation reduces soil N2O emission 总被引:2,自引:0,他引:2
Background and aims
Emission of the greenhouse gas (GHG) nitrous oxide (N2O) are strongly affected by nitrogen (N) fertilizer application rates. However, the role of other nutrients through stoichiometric relations with N has hardly been studied. We tested whether phosphorus (P) availability affects N2O emission. We hypothesized that alleviation of plant P-limitation reduces N2O emission through lowering soil mineral N concentrations.Methods
We tested our hypothesis in a pot experiment with maize (Zea mays L.) growing on a P-limiting soil/sand mixture. Treatment factors included P and N fertilization and inoculation with Arbuscular Mycorrhizal Fungi (AMF; which can increase P uptake).Results
Both N and P fertilization, as well as their interaction significantly (P?<?0.01) affected N2O emission. Highest N2O emissions (2.38 kg N2O-N ha?1) were measured at highest N application rates without P fertilization or AMF. At the highest N application rate, N2O fluxes were lowest (0.71 kg N2O-N ha?1) with both P fertilization and AMF. The N2O emission factors decreased with 50 % when P fertilization was applied.Conclusions
Our results illustrate the importance of the judicious use of all nutrients to minimize N2O emission, and thereby further underline the intimate link between sound agronomic practice and prudent soil GHG management. 相似文献7.
Juan Liu Peikun Jiang Yongfu Li Guomo Zhou Jiasen Wu Fang Yang 《The Botanical review》2011,77(3):320-325
To evaluate the effect of land use change from a natural broadleaf evergreen forest to Moso bamboo plantations and their management
practices on soil N2O efflux in a subtropical region of China, N2O efflux was measured during June 2008 and May 2009 using static closed chamber method. The observed mean N2O fluxes were 0.230, 0.102 and 0.093 mg N2O/m2/h from the intensively managed bamboo forest (IM), conventionally managed bamboo forest (CM), and broadleaf evergreen forest
(BL), respectively, and calculated annual cumulative N2O were 15.8, 8.7 and 7.2 kg N2O/ha, respectively. Soil temperature had significant influence on N2O flux. Whereas there was no correlation between N2O flux and soil water content. Conversion of the natural subtropical broadleaf evergreen forest to Moso bamboo did not increase
soil N2O efflux, but intensive management practices such as regular tillage and fertiliser application, significantly increased soil
N2O emission from bamboo soil. 相似文献
8.
Black alder (Alnus Glutinosa (L.) Gaertn.) trees mediate methane and nitrous oxide emission from the soil to the atmosphere 总被引:7,自引:0,他引:7
Three-year-old seedlings of black alder (Alnus glutinosa (L.) Gaertn.), a common European wetland tree species, were grown in native soil taken from an alder swamp. Fluxes of methane (CH4) and nitrous oxide (N2O) between the tree stem and the atmosphere were determined under controlled conditions. Both CH4 and N2O were emitted through the bark of the stem into the atmosphere when the root zone exhibited higher-than-ambient CH4 and N2O gas mixing ratios. Flooding of the soil caused a decreased N2O emission but an increased CH4 efflux from the stem. Immediately after flooding of the soil, N2O was emitted from the seedlings' bark at a rate of 350 mol N2O m-2 h-1 whereas CH4 flux could not be detected. After more than 40 days of flooding CH4 fluxes up to 3750 mol CH4 m-2 h-1 from the stem were measured, while N2O emission had decreased below the limit of detection. Gas efflux decreased with increasing stem height and correlated with gas mixing ratios in the soil, indicating diffusion through the aerenchyma as the major path of gas transport. From these results it is assumed that woody species with aerenchyma can serve as conduits for soil-derived trace gases into the atmosphere, to date only shown for herbaceous plants. This, yet unidentified, woody plant pathway contributes to the total greenhouse gas source strength of wetlands. 相似文献
9.
Crop residues like corn (Zea mays L.) stover perform important functions that promote soil health and provide ecosystem services that influence agricultural sustainability and global biogeochemical cycles. We evaluated the effect of corn stover removal from a no-till, corn-soybean (Glycine max (L.) Merr) rotation on soil greenhouse gas (GHG; CO2, N2O, CH4) fluxes, crop yields, and soil organic carbon (SOC) dynamics. We conducted a 4-year study using replicated field plots managed with two levels of corn stover removal (none; 55 % stover removal) for four complete crop cycles prior to initiation of ground surface gas flux measurements. Corn and soybean yields were not affected by stover removal with yields averaging 7.28 Mg ha?1 for corn and 2.64 Mg ha?1 for soybean. Corn stover removal treatment did not affect soil GHG fluxes from the corn phase; however, the treatment did significantly increase (107 %, P?=?0.037) N2O fluxes during the soybean phase. The plots were a net source of CH4 (~0.5 kg CH4-C ha?1 year?1 average of all treatments and crops) during the generally wet study duration. Soil organic carbon stocks increased in both treatments during the 4-year study (initiated following 8 years of stover removal), with significantly higher SOC accumulation in the control plots compared to plots with corn stover removal (0–15 cm, P?=?0.048). Non-CO2 greenhouse gas emissions (945 kg CO2-eq ha?1 year?1) were roughly half of SOC (0–30 cm) gains with corn stover removal (1.841 Mg CO2-eq ha?1 year?1) indicating that no-till practices greatly improve the viability of biennial corn stover harvesting under local soil-climatic conditions. Our results also show that repeated corn stover harvesting may increase N loss (as N2O) from fields and thereby contribute to GHG production and loss of potential plant nutrients. 相似文献
10.
A. Vermue L. Philippot N. Munier-Jolain C. Hénault B. Nicolardot 《Plant and Soil》2013,373(1-2):501-514
Aims
Integrated weed management, which allows reducing the reliance of cropping systems on herbicides, is based on the use of specific combinations of innovative agricultural practices. However the impact of the introduction of these practices in cropping systems may influence soil functioning such as biogeochemical cycling. Here, we investigated N2O emissions and the abundances of N-cycling microorganisms in 11-year old cropping systems (i.e. conventional reference and integrated weed management) in order to estimate the environmental side-effects of long-term integrated weed management.Methods
N2O emissions were continuously measured using automated chambers coupled with infrared analysers. Abundances of ammonia oxidizers and denitrifiers together with total bacteria and archaea were determined monthly from 0 to 10 and 10–30 cm soil layer samples by quantitative Polymerase Chain Reaction (qPCR). The relationship between N2O emissions and microbial abundances during the study were investigated as were their relationships with soil physicochemical parameters and climatic conditions.Results
Over 7 months, the system with integrated weed management emitted significantly more N2O with cumulated measured emissions of 240 and 544 g N-N2O ha?1 for conventional and integrated systems, respectively. Abundances of microbial guilds varied slightly between systems, although ammonia-oxidizing bacteria were more abundant in the reference system (1.7 106 gene copies g?1 dry weight soil) compared to the integrated system (1.0 106 gene copies g?1 dry weight soil). These differences revealed both the long-term modification of soil biogeochemical background and the functioning of microbial processes due to 11 years of alternative field management, and the short-term impacts of the agricultural practices introduced as part of weed management during the cropping year.Conclusions
The abundances of the different microbial communities involved in N cycling and the intensity of N2O emissions were not related, punctual high N2O emissions being more dependent on favourable soil conditions for nitrifying and denitrifying activities. Future studies will be performed to check these findings for other pedoclimatic conditions and to examine the impact of such cropping systems. 相似文献11.
Contributions of Autotrophic and Heterotrophic Nitrifiers to Soil NO and N2O Emissions 总被引:4,自引:2,他引:2
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Soil emission of gaseous N oxides during nitrification of ammonium represents loss of an available plant nutrient and has an important impact on the chemistry of the atmosphere. We used selective inhibitors and a glucose amendment in a factorial design to determine the relative contributions of autotrophic ammonium oxidizers, autotrophic nitrite oxidizers, and heterotrophic nitrifiers to nitric oxide (NO) and nitrous oxide (N2O) emissions from aerobically incubated soil following the addition of 160 mg of N as ammonium sulfate kg−1. Without added C, peak NO emissions of 4 μg of N kg−1 h−1 were increased to 15 μg of N kg−1 h−1 by the addition of sodium chlorate, a nitrite oxidation inhibitor, but were reduced to 0.01 μg of N kg−1 h−1 in the presence of nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine], an inhibitor of autotrophic ammonium oxidation. Carbon-amended soils had somewhat higher NO emission rates from these three treatments (6, 18, and 0.1 μg of N kg−1 h−1 after treatment with glucose, sodium chlorate, or nitrapyrin, respectively) until the glucose was exhausted but lower rates during the remainder of the incubation. Nitrous oxide emission levels exhibited trends similar to those observed for NO but were about 20 times lower. Periodic soil chemical analyses showed no increase in the nitrate concentration of soil treated with sodium chlorate until after the period of peak NO and N2O emissions; the nitrate concentration of soil treated with nitrapyrin remained unchanged throughout the incubation. These results suggest that chemoautotrophic ammonium-oxidizing bacteria are the predominant source of NO and N2O produced during nitrification in soil. 相似文献
12.
The contribution of nitrogen transformation processes to total N2O emissions from soils used for intensive vegetable cultivation 总被引:3,自引:0,他引:3
The rapid expansion of intensively farmed vegetable fields has substantially contributed to the total N2O emissions from croplands in China. However, to date, the mechanisms underlying this phenomenon have not been completely understood. To quantify the contributions of autotrophic nitrification, heterotrophic nitrification, and denitrification to N2O production from the intensive vegetable fields and to identify the affecting factors, a 15N tracing experiment was conducted using five soil samples collected from adjacent fields used for rice-wheat rotation system (WF), or for consecutive vegetable cultivation (VF) for 0.5 (VF1), 6 (VF2), 8 (VF3), and 10 (VF4) years. Soil was incubated under 50% water holding capacity (WHC) at 25°C for 96 h after being labeled with 15NH4NO3 or NH 4 15 NO3. The average N2O emission rate was 24.2 ng N?kg?1 h?1 in WF soil, but it ranged from 69.6 to 507 ng N?kg?1 h?1 in VF soils. Autotrophic nitrification, heterotrophic nitrification and denitrification accounted for 0.3–31.4%, 25.4–54.4% and 22.5–57.7% of the N2O emissions, respectively. When vegetable soils were moderately acidified (pH, 6.2 to ?≥?5.7), the increased N2O emissions resulted from the increase of both the gross autotrophic and heterotrophic nitrification rates and the N2O product ratio of autotrophic nitrification. However, once severe acidification occurred (as in VF4, pH?≤?4.3) and salt stress increased, both autotrophic and heterotrophic nitrification rates were inhibited to levels similar to those of WF soil. The enhanced N2O product ratios of heterotrophic nitrification (4.84‰), autotrophic nitrification (0.93‰) and denitrification processes were the most important factors explaining high N2O emission in VF4 soil. Data from this study showed that various soil conditions (e.g., soil salinity and concentration of NO 3 - or NH 4 + ) could also significantly affect the sources and rates of N2O emission. 相似文献
13.
CLAUDIA WAGNER-RIDDLE ADRIANA FURON NICOLE L. MCLAUGHLIN IVAN LEE JOHN BARBEAU SUSANTHA JAYASUNDARA GARY PARKIN PETER von BERTOLDI JON WARLAND 《Global Change Biology》2007,13(8):1722-1736
No‐tillage (NT), a practice that has been shown to increase carbon sequestration in soils, has resulted in contradictory effects on nitrous oxide (N2O) emissions. Moreover, it is not clear how mitigation practices for N2O emission reduction, such as applying nitrogen (N) fertilizer according to soil N reserves and matching the time of application to crop uptake, interact with NT practices. N2O fluxes from two management systems [conventional (CP), and best management practices: NT + reduced fertilizer (BMP)] applied to a corn (Zea mays L.), soybean (Glycine max L.), winter‐wheat (Triticum aestivum L.) rotation in Ontario, Canada, were measured from January 2000 to April 2005, using a micrometeorological method. The superimposition of interannual variability of weather and management resulted in mean monthly N2O fluxes ranging from − 1.9 to 61.3 g N ha−1 day−1. Mean annual N2O emissions over the 5‐year period decreased significantly by 0.79 from 2.19 kg N ha−1 for CP to 1.41 kg N ha−1 for BMP. Growing season (May–October) N2O emissions were reduced on average by 0.16 kg N ha−1 (20% of total reduction), and this decrease only occurred in the corn year of the rotation. Nongrowing season (November–April) emissions, comprised between 30% and 90% of the annual emissions, mostly due to increased N2O fluxes during soil thawing. These emissions were well correlated (r2= 0.90) to the accumulated degree‐hours below 0 °C at 5 cm depth, a measure of duration and intensity of soil freezing. Soil management in BMP (NT) significantly reduced N2O emissions during thaw (80% of total reduction) by reducing soil freezing due to the insulating effects of the larger snow cover plus corn and wheat residue during winter. In conclusion, significant reductions in net greenhouse gas emissions can be obtained when NT is combined with a strategy that matches N application rate and timing to crop needs. 相似文献
14.
1. A number of freshwater invertebrate species emit N2O, a greenhouse gas that is produced in their gut by denitrifying bacteria (direct N2O emission). Additionally, benthic invertebrate species may contribute to N2O emission from sediments by stimulating denitrification because of their bioirrigation behaviour (indirect N2O emission). 2. Two benthic invertebrate species were studied to determine (i) the dependence of direct N2O emission on the preferred diet of the animals, (ii) the regulation of direct N2O emission by seasonally changing factors, such as body size, temperature and availability and (iii) the quantitative relationship between direct and indirect N2O emission. 3. Larvae of the mayfly Ephemera danica, which prefer a bacteria‐rich detritus diet, emitted N2O at rates of up to 90 pmol Ind.?1 h?1 under in situ conditions and 550 pmol Ind.?1 h?1 under laboratory conditions. In contrast, larvae of the alderfly Sialis lutaria, which prefer a bacteria‐poor carnivorous diet, emitted N2O at invariably low rates of 0–20 pmol Ind.?1 h?1. The N2O emission rate of E. danica larvae was positively correlated with seasonally changing factors (body size, temperature and availability). Direct N2O emission by E. danica larvae was limited by low temperature in winter, larval development in spring and low availability in summer. 4. Both E. danica and the non‐emitting S. lutaria increased the total N2O and N2 emission from sediment in a density‐dependent manner. While N2O directly emitted by benthic invertebrates can be partially consumed in the sediment (E. danica), non‐emitting species can still indirectly contribute to total N2O emission from sediment (S. lutaria). 相似文献
15.
Background and Aims
Great attention has been paid to N2O emissions from paddy soils under summer rice-winter wheat double-crop rotation, while less focus was given to the NO emissions. Besides, neither mechanism is completely understood. Therefore, this study aimed at evaluating the relative importance of nitrification and denitrification to N2O and NO emissions from the two soils at different soil moisture contentsMethods
N2O and NO emissions during one winter wheat season were simultaneously measured in situ in two rice-wheat based field plots at two different locations in Jiangsu Province, China. One soil was neutral in pH with silt loam texture (NSL), the other soil alkaline in pH with a clay texture (AC). A 15?N tracer incubation experiment was conducted in the laboratory to evaluate the relative importance of nitrification and denitrification for N2O and NO emissions at soil moisture contents of 40 % water holding capacity (WHC), 65 % WHC and 90 % WHC.Results
Higher N2O emission rates in the AC soil than in the NSL soil were found both in the field and in the laboratory experiments; however, the differences in N2O emissions between AC soil and NSL soil were smaller in the field than in the laboratory. In the latter experiment, nitrification was observed to be the more important source of N2O emissions (>70 %) than denitrification, regardless of the soils and moisture treatments, with the only exception of the AC soil at 90 % WHC, at which the contributions of nitrification and denitrification to N2O emissions were comparable. The ratios of NO/N2O also supported the evidence that the nitrification process was the dominant source of N2O and NO both in situ and in the laboratory. The proportion of nitrified N emitted as N2O (P N2O ) in NSL soil were around 0.02 % in all three moisture treatments, however, P N2O in the AC soil (0.04 % to 0.10 %) tended to decrease with increasing soil moisture content.Conclusions
Our results suggest that N2O emission rates obtained from laboratory incubation experiments are not suitable for the estimation of the true amount of N2O fluxes on a field scale. Besides, the variations of P N2O with soil property and soil moisture content should be taken into account in model simulations of N2O emission from soils. 相似文献16.
Role of Microorganisms in Emission of Nitrous Oxide and Methane in Pulse Cultivated Soil Under Laboratory Incubation Condition 总被引:1,自引:0,他引:1
Jyotsnarani Jena Sanak Ray Haragobinda Srichandan Anuradha Das Trupti Das 《Indian journal of microbiology》2013,53(1):92-99
Soil from a pulse cultivated farmers land of Odisha, India, have been subjected to incubation studies for 40 consecutive days, to establish the impact of various nitrogenous fertilizers and water filled pore space (WFPS) on green house gas emission (N2O & CH4). C2H2 inhibition technique was followed to have a comprehensive understanding about the individual contribution of nitrifiers and denitrifiers towards the emission of N2O. Nevertheless, low concentration of C2H2 (5 ml: flow rate 0.1 kg/cm2) is hypothesized to partially impede the metabolic pathways of denitrifying bacterial population, thus reducing the overall N2O emission rate. Different soil parameters of the experimental soil such as moisture, total organic carbon, ammonium content and nitrate–nitrogen contents were measured at regular intervals. Application of external N-sources under different WFPS conditions revealed the diverse role played by the indigenous soil microorganism towards green house gas emission. Isolation of heterotrophic microorganisms (Pseudomonas) from the soil samples, further supported the fact that denitrification might be prevailing during specific conditions thus contributing to N2O emission. Statistical analysis showed that WFPS was the most influential parameter affecting N2O formation in soil in absence of an inhibitor like C2H2. 相似文献
17.
Nitrous oxide fluxes from corn fields: on-farm assessment of the amount and timing of nitrogen fertilizer 总被引:5,自引:0,他引:5
B. L. MA T. Y. WU N. TREMBLAY† W. DEEN‡ M. J. MORRISON N. B. MCLAUGHLIN E. G. GREGORICH G. STEWART‡ 《Global Change Biology》2010,16(1):156-170
Nitrogen fertilization is considered as an important source of atmospheric N2O emission. A seven site‐year on‐farm field experiment was conducted at Ottawa and Guelph, ON and Saint‐Valentin, QC, Canada to characterize the affect of the amount and timing of N fertilizer on N2O emission in corn (Zea mays L.) production. Using the static chamber method, gas samples were collected for 28‐days after preplant and 28‐days after sidedress fertilization at the seven site‐year, resulting in 14 monitoring periods. For both methods of fertilization, peak N2O flux and cumulative emission increased with the amount of N applied, with rates ranging from 30 to 900 μg N m?2 h?1. Depending on N amount and time of application, cumulative emission varied from 0.05 to 2.42 kg N ha?1, equivalent to 0.03% to 1.45% of the N fertilizer applied. Differences in N2O emission peaks among fertilizer treatments were clearly separated in 13 out of 14 monitoring periods. Total N2O emissions may have been underestimated compared with annual monitoring in 10 out of the 49 cases because the monitoring period ended before N2O efflux returned to the baseline level. The flux of N2O was negligible when soil mineral N in the 0–15 cm layer was < 20 mg N kg?1. While rainfall stimulated emission, soil temperature > 15 °C was likely the driving force responsible for the higher levels of N2O found for sidedress than preplant application methods. However, caution must be taken when interpreting these later results as preplant fertilization may have continuously stimulated N2O emissions after the 28‐days monitoring period, especially in situations where N2O effluxes have not fallen back to their baseline levels. Increasing fertilizer rates from 90 to 150 kg N ha?1 resulted in slight increases in yields, but doubled cumulative N2O emissions. 相似文献
18.
In annual crops, the partitioning of photosynthates to support root growth, respiration and rhizodeposition should be greater during early development than in later reproductive stages due to source/sink relationships in the plant. Therefore, seasonal fluctuations in carbon dioxide (CO2) and nitrous oxide (N2O) production from roots and root-associated soil may be related to resource partitioning by the crop. Greenhouse studies used 13C and 15N stable isotopes to evaluate the carbon (C) partitioning and nitrogen (N) uptake by corn and soybean. We also measured the CO2 and N2O production from planted pots as affected by crop phenology and N fertilization. Specific root-derived respiration was related to the 13C allocated to roots and was greatest during early vegetative growth. Root-derived respiration and rhizodeposition were greater for corn than soybean. The 15N uptake by corn increased between vegetative growth, tasseling and milk stages, but the 15N content in soybean was not affected by phenology. A peak in N2O production was observed with corn at the milk stage, suggesting that the corn rhizosphere supported microbial communities that produced N2O. Most of the 15N-NO3 applied to soybean was not taken up by the plant and negative N2O production during vegetative growth and floral initiation stages suggests that soybean roots supported the reduction of N2O to dinitrogen (N2). We conclude that crop phenology and soil N availability exert important controls on rhizosphere processes, leading to temporal variation in CO2 and N2O production. 相似文献
19.
Emissions of nitrous oxide from the leaves of grasses 总被引:1,自引:0,他引:1
Saman Bowatte Paul C. D. Newton Phil Theobald Shona Brock Chris Hunt Mark Lieffering Scott Sevier Steve Gebbie Dongwen Luo 《Plant and Soil》2014,374(1-2):275-283
Aims
Nitrous oxide (N2O) emissions from pastoral agriculture are considered to originate from the soil as a consequence of microbial activity during soil nitrification and denitrification. However, recent studies have identified the plant canopy as a potentially significant source of N2O emissions to the atmosphere. Understanding the extent and mechanisms of plant emissions may provide new mitigation opportunities as current options only target soil microbial processes.Methods
We developed an experimental apparatus and protocol to partition N2O emissions between the leaves of grasses and the soil and measured emissions from ten common grass species found in New Zealand pastures.Results
The chamber design enabled us to identify measurable changes in N2O concentration over a period of 1 h and to distinguish a range of emissions from 0.001 to 0.25 mg N2O-N/m2 leaf area/h. There was a 10-fold variation among species; Holcus lanataus, Lolium perenne and Paspalum dilatatum had the highest leaf N2O emissions and Poa annua the lowest.Conclusions
Grasses do emit N2O from their leaves and the rate that this occurs varies among grass species. The emission does not appear to arise from formation of N2O in plant leaves but more likely reflects transport of N2O from the soil. Differences in emission rates appear to arise from a plant influence on the rate of formation of N2O in the soil rather than the rate of transportation through the plant. 相似文献20.
土壤溶解性有机物对CO_2和N_2O排放的影响 总被引:3,自引:0,他引:3
农田土壤是温室气体的重要排放源,溶解性有机物作为土壤微生物容易利用的基质,其含量变化与温室气体的产生和排放密切相关。基于室内培养试验,对溶解性有机物影响土壤CO2、N2O的排放过程进行了分析。设置空白(CK)、单施秸秆(S)、单施氮肥(N)、秸秆和氮肥(S+N)4个不同的处理,对添加不同物质条件下土壤溶解性有机碳(DOC)、溶解性有机氮(DON)和CO2、N2O的排放动态进行了研究,对DOC和DON影响CO2、N2O的排放过程进行了探讨。结果表明:不同处理的温室气体排放通量和土壤DOC、DON含量差异显著;各处理的CO2排放通量和DOC动态随培养时间的延长呈现逐渐减小的趋势,S和S+N处理的N2O排放和DON动态呈现先增大后减小的趋势;S+N处理的CO2排放量最高,DON含量也显著高于其他处理,单施秸秆(S)处理的N2O排放量和DOC含量显著高于其它处理,单施氮肥(N)对土壤CO2的排放量和DOC含量的影响较小;土壤CO2和N2O的排放通量与土壤DOC和DON含量呈显著的相关性,相关系数(R2)达0.6以上,说明溶解性有机物的含量和动态对CO2、N2O的排放过程产生显著影响。 相似文献