Applicability of the soil gradient method for estimating soil–atmosphere CO2, CH4, and N2O fluxes for steppe soils in Inner Mongolia

For evaluating the applicability of the soil gradient method as a substitute for CO₂‐, CH₄‐, and N₂O‐flux measurements in steppe, we carried out chamber measurements and determined soil gas concentration at an ungrazed (UG99) and a grazed (WG) site in Inner Mongolia, China. The agreement of the concentration‐based flux estimates with measured chamber‐based fluxes varied largely depending on the respective GHG in the sequence CO₂ > CH₄ >> N₂O. A calibration of the gas‐transport parameter used to calculate fluxes based on soil gas concentrations improved the results considerably for CO₂ and CH₄. After calibration, the average deviation from the chamber‐based annual cumulative flux for both sites was 11.5%, 10.5%, and 59% for CO₂, CH₄, and N₂O. The gradient method did not constitute an adequate stand‐alone substitute for greenhouse‐gas flux estimation since a calibration using chamber‐based measurements was necessary and vigorous production processes were confined to the uppermost, almost water‐saturated soil layer.     

Automated Collector of Terrestrial Systems Used for the Gathering of Soil Atmospheric‐Gas Emissions

Soil greenhouse gas (GHG) emissions are complex, and their study requires considerable sampling of field spatial and temporal differences. Manual and simple automated gas‐collection techniques used at multiple sites during specific time intervals are labor intensive. The objective of this work was to construct a device that can independently collect GHG samples with the accuracy and precision of manually drawn samples. An automated collector of terrestrial systems (ACTS) is a 24‐h, 7‐d/week programmable sampler used in the field for real‐time gathering and containment of soil GHG emissions. The sampler opens and closes an exterior soil gas chamber, mixes gases in the chamber by turning fans on/off, and utilizes programmable circuits to purge the system and draw a sample from the chamber with a pneumatic‐driven syringe. Each sample was stored in an evacuated vial held in a 30‐vial capacity carousel. Vial content was analyzed for carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) at the U.S. Department of Agriculture (USDA)–Agricultural Research Services (ARS) Agroecosystem Management Research Unit (AMRU). A Tracor MT‐220 gas chromatograph (GC) configured with a thermal conductivity detector (TCD) was used for CO₂ analysis, and an automated gas‐sampling system (AGSS) attached to a Varian 3700 GC configured with flame ionization detection (FID) and electron capture detection (ECD) was used for CH₄ and N₂O analysis. Field and laboratory mean values and coefficients of variation (standards and field concentrations of CO₂, CH₄, and N₂O ranging from ambient to 71 kg ha^?1 d^?1 had coefficients of variation ranging from 1.2 to 4.2%) were similar between ACTS and manually drawn samples. Results showed strong correlation (R² = 0.81 to 1.00) between sampling methods. The sampler design provides a realistic and inexpensive approach for collecting emission samples while reducing human error associated with adverse sampling conditions and fatigue. The ACTS has potential for use in monitoring and comparing management practices in terrestrial systems to determine their contribution to GHG emissions.     

Gaseous emissions and soil fertility of homegardens in the Nuba Mountains,Sudan

Intensification of homegardens in the Nuba Mountains may lead to increases in C and nutrient losses from these small‐scale land‐use systems and potentially threaten their sustainability. This study, therefore, aimed at determining gaseous C and N fluxes from homegarden soils of different soil moisture, temperature, and C and N status. Emissions of CO₂, NH₃, and N₂O from soils of two traditional and two intensified homegardens and an uncultivated control were recorded bi‐weekly during the rainy season in 2010. Flux rates were determined with a portable dynamic closed chamber system consisting of a photo‐acoustic multi‐gas field monitor connected to a PTFE coated chamber. Topsoil moisture and temperature were recorded simultaneously to the gas measurements. Across all homegardens emissions averaged 4,527 kg CO₂‐C ha^?1, 22 kg NH₃‐N ha^?1, and 11 kg N₂O‐N ha^?1 for the observation period from June to December. Flux rates were largely positively correlated with soil moisture and predominantly negatively with soil temperature. Significant positive, but weak (r_s < 0.34) correlations between increasing management intensity and emissions were noted for CO₂‐C. Similarly, morning emissions of NH₃ and increasing management intensity were weakly correlated (r_s = 0.17). The relatively high gaseous C and N losses in the studied homegardens call for effective management practices to secure the soil organic C status of these traditional land‐use systems.     

Variations in the Diurnal Flux of Greenhouse Gases from Soil and Optimizing the Sampling Protocol for Closed Static Chambers

There is no standardized method for the sampling of greenhouse gas fluxes from soil. Two methods are primarily used: closed dynamic chamber (CDC) and closed static chamber (CSC) systems. The most complex and costly are the CDC systems, which can sample gases in situ. However, the low-cost CSC systems are being increasingly used in which the gas samples are collected manually and analyzed off-site at a later date. Given their growing popularity, it is important to optimize the sampling procedure of the CSC systems to ensure that the measurements are both repeatable and representative. Samples from a commercial potato crop were collected in the morning and afternoon at 0, 15, 30, 60, 90, and 120 min after the chambers were closed, and the concentrations of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) were determined using gas chromatography. The concentrations of CO₂ and N₂O inside chambers increased linearly over time, whereas the concentration of CH₄ remained constant. The fluxes of CO₂ and N₂O from soil were greater in the afternoon than the morning, whereas the flux of CH₄ was greater in the morning. For longer-term single-point soil flux monitoring using CSCs with a volume of 6.3 L, it is recommended that samples are collected in the morning at 0, 30, and 60 min after chambers are closed. This approach will ensure that the concentration of the gases are representative and will allow for a high level of repeatability and certainty in the results.     

Above and Below Ground Measurements of Greenhouse Gases from Swine Effluent Amended Soil

Abstract

As a means of economic disposal and to reduce need for chemical fertilizer, waste generated from swine production is often applied to agricultural land. However, there remain many environmental concerns about this practice. Two such concerns, contribution to the greenhouse effect and stratospheric ozone depletion by gases emitted from waste‐amended soils, have not been thoroughly investigated. An intact core study at Auburn University (32 36′N, 85 36′W) was conducted to determine the source‐sink relationship of three greenhouse gases in three Alabama soils (Black Belt, Coastal Plain, and Appalachian Plateau regions) amended with swine waste effluent. Soil cores were arranged in a completely random design, and treatments used for each soil type consisted of a control, a swine effluent amendment (112 kg N ha^?1), and an ammonium nitrate (NH₄NO₃) fertilizer amendment (112 kg N ha^?1). During a 2‐year period, a closed‐chamber technique was used to determine rates of emission of nitrous oxide (N₂O)–nitrogen (N), carbon dioxide (CO₂)–carbon (C), and methane (CH₄)–C from the soil surface. Gas probes inserted into the soil cores were used to determine concentrations of N₂O‐N and CO₂‐C from depths of 5, 15, and 25 cm. Soil water was collected from each depth using microlysimeters at the time of gas collection to determine soil‐solution N status. Application of swine effluent had an immediate effect on emissions of N₂O‐N, CO₂‐C, and CH₄‐C from all soil textures. However, greatest cumulative emissions and highest peak rates of emission of all three trace gases, directly following effluent applications, were most commonly observed from sandier textured Coastal Plain and Appalachian Plateau soils, as compared to heavier textured Black Belt soil. When considering greenhouse gas emission potential, soil type should be a determining factor for selection of swine effluent waste disposal sites in Alabama.     

Procedure for Fast Simultaneous Analysis of the Greenhouse Gases: Methane,Carbon Dioxide,and Nitrous Oxide in Air Samples

Abstract

A comprehensive procedure has been developed and is reported here for (i) sampling air above a soil surface and (ii) analyzing it for the three greenhouse gases: methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O). The automated gas‐chromatography procedure simultaneously analyzes for CH₄, CO₂, and N₂O and has a precision of 0.87, 2.17, and 0.74%, respectively. Method-detection limits are 0.04 ppm for CH₄, 25.5 ppm for CO₂, and 7.4 ppb for N₂O. The procedure is used to monitor greenhouse gas exchanges at soil surfaces; its precision and automated ability to analyze large sample numbers produces quality data available for upscaling and modeling for inventory purposes; and it is used for developing a process‐based understanding of the mechanisms controlling greenhouse gas fluxes at the soil surface, which can then be applied to develop mitigation strategies.     

不同秸秆还田年限对稻麦轮作系统温室气体排放的影响

为揭示稻麦轮作系统不同秸秆还田年限下温室气体排放特征及减排调控机制,本研究采用大田小区试验,考察了稻麦轮作不同秸秆还田年限[空白对照(CK)、常规处理秸秆不还田(NT)、1年秸秆还田(SR1)和5年秸秆还田(SR5)]对CH4、CO2和N2O 3种温室气体排放规律的影响,同时测定了土壤固碳量,估算了秸秆焚烧产生的温室气体排放量,综合计算了4种处理对全球变暖的贡献。试验结果表明,SR1和SR5均显著提升CH4和CO2的排放通量,分别高出NT、CK处理73.52%、309.49%和13.29%、13.06%;同时显著降低N2O排放通量,较NT降低29.68%和42.55%;但SR1和SR5之间温室气体排放通量差异不显著;与NT相比,SR1和SR5可以显著提高土壤固碳量517.9%和709.03%,SR5土壤固碳量高出SR1达30.93%;NT秸秆焚烧产生的全球气温变暖贡献为9 698.49 kg(CO2-eqv)·hm?2,比CK高126.98%。综合分析温室气体排放、土壤固碳以及秸秆焚烧3个因素,SR1全球升温贡献最低,显著低于NT 4.72%。短期全量秸秆还田有助于降低总体温室气体排放,长期进行秸秆还田后降低幅度会逐步减小。     

Measuring the CO2 production from maize‐straw‐amended soil columns— a comparison of four methods

A soil‐column experiment with maize‐straw application at different depths was carried out to investigate the accuracy of CO₂‐measurement systems in a greenhouse experiment with sandy and loamy soils. The classical approach of CO₂ absorption in NaOH solution was compared with three other methods using dynamic chambers. These methods were gas chromatography (GC), a portable infrared analyzer (IR), and a portable photo‐acoustic system (PAS). The cumulative CO₂ production over the 57‐day incubation period was significantly affected by the method and soil‐specifically by the treatments. The NaOH and GC method always formed a pair of lowest cumulative CO₂ production in all treatments with maize‐straw addition. In the treatments with bottom application of the maize straw, IR and PAS methods gave values at identical levels in both soils. In the treatments with top application of the maize straw, the IR method gave significantly highest values in the sandy soil and the PAS method in the loamy soil. The correlation coefficients between the cumulative CO₂ production of the three dynamic‐chamber methods (GC, IR, and PAS) and the static NaOH method were all significant, with r values between 0.90 and 0.93. The C balance can be used for testing the plausibility of CO₂‐production data. Roughly 102% (NaOH and GC) and 114% (IR and PAS) were recovered, including the CO₂‐production data in the C balance of the sandy soil. The respective data were 97% (NaOH and GC) and 104% (IR and PAS) for the loamy soil.     

Growth and photosynthesis of salt‐stressed sunflower (Helianthus annuus) plants as affected by foliar‐applied different potassium salts

In order to assess the effectiveness of foliar‐applied potassium (K⁺, 1.25%) using different salts (KCl, KOH, K₂CO₃, KNO₃, KH₂PO₄, and K₂SO₄) in ameliorating the inhibitory effect of salt stress on sunflower plants, a greenhouse experiment was conducted. Sodium chloride (150 mM) was applied through the rooting medium to 18 d–old plants and after 1 week of salt treatment; different K⁺‐containing salts were applied twice in 1‐week interval as a foliar spray. Salt stress adversely affected the growth, yield components, gas exchange, and water relations, and also caused nutrient imbalance in sunflower plants. However, foliar‐applied different sources of potassium improved shoot and root fresh and shoot dry weights, achene yield, 100‐achene weight, photosynthetic rate, transpiration rate, stomatal conductance, water‐use efficiency, relative water content, and leaf and root K⁺ concentrations of sunflower plants grown under saline conditions. Under nonsaline conditions, improvement in shoot fresh weight, achene yield, 100‐achene weight, photosynthetic and transpiration rates, and root Na⁺ concentration was observed due to foliar‐applied different K sources. Of the different salts, K₂SO₄, KH₂PO₄, KNO₃, and K₂CO₃ were more effective than KCl and KOH in improving growth and some key physiological processes of sunflower plants.     

Influence of air porosity on distribution of gases in soil under assay for denitrification

 There has been concern that the measurement of gas emissions from a soil surface may not accurately reflect gas production within the soil profile. But, there have been few direct assessments of the error associated with the use of surface emissions for estimating gas production within soil profiles at different water contents. To determine the influence of air porosity on the distribution of gases within soil profiles, denitrification assays were performed using soil columns incubated with different water contents to provide air porosities of 18%, 13%, and 0% (equivalent to 62%, 73%, and 100% water-filled pore space, respectively). The soil columns were formed by packing sieved soil into cylinders which could be sealed at the top to form a headspace for the measurement of surface emissions of soil gases. Gas-permeable silicone tubing was placed at three depths (4.5, 9, and 13.5 cm) within each soil core to permit the measurement of gas concentration gradients within the soil core. Assays for denitrification were initiated by the addition of acetylene (5 kPa) to the soil column, and gas samples were taken from both the headspace and gas-permeable tubing at various times during a 46-h incubation. The results showed that at 18% air porosity, the headspace gases were well equilibrated with pore-space gases, and that gas emissions from the soil could provide good estimates of N₂O and CO₂ production. At air porosities of 13% and 0%, however, substantial storage of these gases occurred within the soil profiles, and measurements of surface emissions of gas from the soils greatly underestimated gas production. For example, the sole use of N₂O emission measurements caused three to five fold underestimates of N₂O production in soil maintained at 13% air porosity. It was concluded that the confounding influence of soil moisture on gas production and transport in soil greatly limits the use of surface emissions as a reliable indicator of gas production. This is particularly pertinent when assessing processes such as denitrification in which N gas production is greatly promoted by the conditions that limit O₂ influx and concurrently limit N gas efflux. Received: 15 January 1999     

An improved method for measuring soil N2O fluxes using a quantum cascade laser with a dynamic chamber

A dynamic chamber method was developed to measure fluxes of N₂O from soils with greater accuracy than previously possible, through the use of a quantum cascade laser (QCL). The dynamic method was compared with the conventional static chamber method, where samples are analysed subsequently on a gas chromatograph. Results suggest that the dynamic method is capable of measuring soil N₂O fluxes with an uncertainty of typically less than 1–2 µg N₂O‐N m^?2 hour^?1 (0.24–0.48 g N₂O‐N ha^?1 day^?1), much less than the conventional static chamber method, because of the greater precision and temporal resolution of the QCL. The continuous record of N₂O and CO₂ concentration at 1 Hz during chamber closure provides an insight into the effects that enclosure time and the use of different regression methods may introduce when employed with static chamber systems similar in design. Results suggest that long enclosure times can contribute significantly to uncertainty in chamber flux measurements. Non‐linear models are less influenced by effects of long enclosure time, but even these do not always adequately describe the observed concentrations when enclosure time exceeds 10 minutes, especially with large fluxes.     

An explanation of linear increases in gas concentration under closed chambers used to measure gas exchange between soil and the atmosphere

Earlier models describing the accumulation of gases under closed chambers are based on the assumption of a constant concentration source that does not change during the time of chamber deployment. A new model is proposed which is based on the assumption of a constant production source, and takes into account possible changes in gas concentrations at the source during chamber deployment. Using N₂O as an example, simulations have been carried out for different source strength and depth, diffusivities and air porosities. The main finding was a chamber‐induced increase in gas concentrations in the upper part of the soil profile, including the depth where the N₂O source is located. The increase started immediately after chamber closure. Nevertheless, fluxes calculated from increasing concentrations within the chamber's headspace were always less than those expected under undisturbed conditions, i.e. in the absence of a chamber. This was due to a proportion of the gas produced being stored within the soil profile while the chamber was in place. The discrepancy caused by this effect increased with increasing air‐filled porosity and decreasing height of the chamber, and a procedure for correcting chamber flux measurements accordingly is proposed. The increase in soil gas concentrations after chamber closure was confirmed in a laboratory experiment.     

Emissions of trace gases (CO2, CO,CH4, and N2O) resulting from rice straw burning

Emissions of trace gases (CO₂, CO, CH₄, N₂O) resulting from rice straw burning were measured by using the open chamber method. The carbon contained in rice straw was mainly released to the atmosphere as CO₂. The percentage of CO₂-C emitted in total C in rice straw was in the range of 57–81%, followed by CO-C (5–9%). The percentages of CH₄-C and N₂O-N in total C and N in rice straw were in the range of 0.43–0.90 and 1.16–1.50%, respectively. In the case of the rice straw which had been left in the field for a period of one month after harvest, emission of imperfect combustible gases such as CO and CH₄ during burning increased slightly, while that of perfect combustible gas, CO₂, was reduced. The amount of CH₄ emission from rice straw burning was comparable to that from paddy fields.     

A modified McIntyre and Phillip approach to measure top‐soil gas diffusivity in‐situ

The McIntyre and Phillip method yields the product of a gas‐diffusion coefficient (D_S) and the gas‐filled proportion of soil volume ε. Until now, ε had to be measured independently from soil cores in order to obtain D_S. To avoid soil sampling, we broke up chamber measurement results by means of an empirical relationship D_S= f(ε). In contrast to an exclusive use of such an empirical relationship, this approach is advantageous in that the site‐specific information concerning pore continuity is integrated into the result. Another modification involves the use of a non‐linear regression technique, which fits the unknown parameters of the mechanistic dilution function of the tracer gas to the measured values. In this way, the independent measurement of chamber clearance with a ruler could be replaced with an estimation based on the dilution function. We could then show, by means of a Monte Carlo simulation, that the exponential parameter of the dilution function contributes to the highest error of the diffusion coefficient estimation from the 6 input parameters. We then compared the results of the following methods at 6 sites. The methods included: (a) the approach described above, (b) the laboratory measurement on soil cores, and (c) the original McIntyre and Philip method. This method is a combination of in‐situ chamber measurement and laboratory measurement of the air‐filled soil fraction. We did not detect any significant differences in the means of our method (a) in any of the aforementioned cases, as well as in the laboratory measurement (b). Deviations between individual measurements could be attributed to differences in spatial integration. These deviations are a result of scale‐dependent spatial heterogeneity and thereby provide site‐specific information on soil structure.     

Fluxes of climate‐relevant trace gases between a Norway spruce forest soil and atmosphere during repeated freeze–thaw cycles in mesocosms

For this century, an increasing frequency of extreme meteorological boundary conditions is expected, presumably resulting in a changing frequency of freezing and thawing of soils in higher‐elevation areas. Our current knowledge about the effects of these events on trace‐gas emissions from soils is scarce. In this study, the effects of freeze–thaw events on the fluxes of the trace gases CO₂, N₂O, and NO between soil and atmosphere were investigated in a laboratory experiment. Undisturbed soil columns were collected from a mature Norway spruce forest in the “Fichtelgebirge”, SE Germany. The influence of freezing temperatures (–3°C, –8°C, –13°C) on gas fluxes was studied during the thawing periods (+5°C) in three freeze–thaw cycles (FTCs) and compared to unfrozen controls (+5°C). Two different types of soil columns were examined in parallel—one consisting of O layer only (O columns) and one composed of O layer and mineral soil horizons (O+M columns)—to quantify the contribution of the organic layer and the top mineral soil to the production or consumption of these trace gases. During the thawing period, we observed increasing emissions of CO₂, N₂O, and NO from the spruce forest soil, but the cumulative emissions of these gases did mostly not exceed the level of the controls. The results show that the O layers were mainly involved in the gas production. Severe soil frost increased CO₂ fluxes during soil thawing, whereas repetition of the freeze–thaw events decreased CO₂ fluxes from the thawing soil. Fluxes of N₂O and NO were neither influenced by freezing temperature nor by freeze–thaw repetition. Stable‐isotope analysis indicated that denitrification was mostly responsible for the N₂O production in the FTC columns. Furthermore, isotope data demonstrated a consumption of N₂O through microbial denitrification to N₂. It was further shown, that production of N₂O also occurred in the mineral horizons. The NO emissions were mainly driven by increasing soil temperature during thawing. In this freeze–thaw experiment up to 20 times higher NO than N₂O fluxes were recorded. Our results suggest that topsoil thawing has little potential to increase the emissions of CO₂, N₂O, and NO in spruce forest soils.     

A comparison of regression methods for estimating soil-atmosphere diffusion gas fluxes by a closed-chamber technique

Continuous changes in methane (CH₄) and carbon dioxide (CO₂) concentrations inside a closed chamber were measured on the forest floor at three sites: a deciduous forest and a coniferous forest in Hokkaido, Japan, and a birch forest in West Siberia, Russian Federation. Flux estimations by three types of regression methods, exponential, nonlinear, and linear, were examined using field-collected concentration data. The pattern of change with time of the gas concentration in the headspace differed, mainly according to site but also, to a lesser extent, according to the gas. This was a function of both the chamber height and surface soil property relating to soil gas diffusion and the gas concentration profile. Flux estimations did not differ statistically between the exponential and nonlinear methods for either gas at any site, because both of those regression methods were based on diffusion theory. However, the flux values estimated by linear regression were significantly different from those estimated by the other two methods for both CH₄ and CO₂ at the deciduous forest site and for CO₂ at the coniferous forest site. Shortening the chamber deployment period improved the linearity of the curve, but did not completely eliminate the error. Our results suggest that linear regression is not a good model of the change in headspace concentration with time.     

Simple modelling of the sorption of iron‐cyanide complexes on ferrihydrite

The sorption of the iron‐cyanide complexes ferricyanide, [Fe(CN)₆]^3—, and ferrocyanide, [Fe(CN)₆]^4—, on ferrihydrite was investigated in batch experiments including the effects of pH (pH 3.5 to 8) and ionic strength (0.001 to 0.1 M). The pH‐dependent sorption data were evaluated with a model approach by Barrow (1999): c = a exp(bS)S/(S_max‐S), where c is the solution concentration; S is the sorbed amount; S_max is maximum sorption; b is a parameter; and a is a parameter at constant pH. Ferricyanide sorption was negatively affected by increasing ionic strength, ferrocyanide sorption not at all. More ferricyanide than ferrocyanide was sorbed in the acidic range. In the neutral range the opposite was true. Fitting the pH‐dependent sorption to the model resulted in a strong correlation for both iron‐cyanide complexes with a common sorption maximum of 1.6 μmol m^—2. Only little negative charge was conveyed to the ferrihydrite surface by sorption of iron‐cyanide complexes. The sorption of iron‐cyanide complexes on ferrihydrite is weaker than that on goethite, as a comparison of the model calculations shows. This may be caused by the lower relative amount of high‐affinity sites present on the ferrihydrite surface.     

A new sampling technique to monitor concentrations of CH4, N2O and CO2 in air at well‐defined depths in soils with varied water potential

A new sampling technique for measuring the concentrations of trace gases (CH₄, CO₂ and N₂O) in the soil atmosphere from well‐defined depths is described. Probes are constructed from silicone tubing closed with silicone septa on both ends, thereby dividing an inner air space from the outer soil atmosphere without a direct contact. The gas exchanges between the inner and outer atmosphere only by diffusion through the walls of the silicone tube. Tests revealed that the gases N₂O, CO₂ and CH₄ in the enclosed space reached 95% equilibrium with the surrounding atmosphere at 20°C within 7 h or faster. The probe measurements are reproducible: the standard deviation of samples taken from 26 probes stored in the laboratory atmosphere equalled that of a standard gas. The probes can easily be constructed and installed at specified depths in the soil. The method has the following advantages compared with other methods that use spaces with holes in them for gas exchange: (i) the silicone probe enables trace gases to be sampled in wet soils, including ones that are waterlogged or temporarily saturated; (ii) the sampling itself does not create low pressure and hence does not create mass flow in the soil matrix from undefined depths; and (iii) the probe can be made to take samples of gas of any required size. The silicone probes did not show ageing effects during 18 months of use in the field in a mineral soil under grass. The probes yielded comparable results: three probes inserted at 5 cm depth in a uniformly treated 100‐m² plot provided nearly identical average trace gas concentrations within the measurement period.     

华北平原高产农区冬小麦农田土壤温室气体排放及其综合温室效应

研究不同农业管理措施下小麦农田N2O、CO2、CH4等温室气体的综合增温潜势,有助于科学评价农业管理措施在减少温室气体排放和减缓全球变暖方面的作用,为制定温室气体减排措施提供依据。本研究采用静态明箱气相色谱法对华北平原高产农区4种农业管理措施下冬小麦农田土壤温室气体(CO2、CH4和N2O)季节排放通量进行了监测,估算了不同农业管理措施下小麦季的综合温室效应。结果表明,华北太行山前平原冬小麦农田土壤是CO2、N2O的排放源,CH4的吸收汇。不同农业管理措施对不同温室气体的排放源和吸收汇强度的影响不同,增施氮肥、充分灌溉促进了土壤CO2、N2O的生成,强化了土壤CO2和N2O排放源的特征;但却抑制了土壤对CH4的氧化,弱化了土壤作为大气CH4吸收汇的特征。2009—2010年和2010—2011年冬小麦生长季T1(传统模式)、T2(高产高效模式)、T3(再高产模式)和T4(再高产高效和土壤生产力提高模式)处理土壤排放的温室气体碳当量分别依次为8 880 kg(CO2).hm 2、8 372 kg(CO2).hm 2、9 600 kg(CO2).hm 2、9 318kg(CO2).hm 2和13 395 kg(CO2).hm 2、12 904 kg(CO2).hm 2、13 933 kg(CO2).hm 2、13 189 kg(CO2).hm 2。各处理间温室气体排放差异主要是由于施肥和灌溉措施的不同引起的,秸秆还田与否是造成年度间温室气体排放存在差异的主要原因。T2处理综合增温潜势相对较低,产量和产投比相对较高,为本区域冬小麦优化管理模式。