2O Emissions Research Articles

Rice husk and melaleuca biochar additions reduce soil CH 4 and N 2O emissions and increase soil physicochemical properties.

Background: Biochar is a promising material in mitigating greenhouse gases (GHGs) emissions from paddy fields due to its remarkable structural properties. Rice husk biochar (RhB) and melaleuca biochar (MB) are amendment materials that could be used to potentially reduce emissions in the Vietnamese Mekong Delta (VMD). However, their effects on CH 4 and N 2O emissions and soil under local water management and conventional rice cultivation have not been thoroughly investigated. Methods: We conducted a field experiment using biochar additions to the topsoil layer (0-20 cm). Five treatments comprising 0 t ha -1 (CT0); 5 t ha -1 (RhB5) and 10 t ha -1 (RhB10), and 5 t ha -1 (MB5) and 10 t ha -1 (MB10) were designed plot-by-plot (20 m 2) in triplicates. Results: The results showed that biochar application from 5 to 10 t ha -1 significantly decreased cumulative CH 4 (24.2-28.0%, RhB; 22.0-14.1%, MB) and N 2O (25.6-41.0%, RhB; 38.4-56.4%, MB) fluxes without a reduction in grain yield. Increasing the biochar application rate further did not decrease significantly total CH 4 and N 2O fluxes but was seen to significantly reduce the global warming potential (GWP) and yield-scale GWP in the RhB treatments. Biochar application improved soil Eh but had no effects on soil pH. Whereas CH 4 flux correlated negatively with soil Eh ( P <0.001; r 2 = 0.552, RhB; P <0.001; r 2 = 0.502, MB). Ameliorating soil aeration and functions by adding RhB and MB resulted in improving soil physicochemical properties, especially significant SOM and AN boosting, which indicate better soil health, structure, and fertility. Conclusions: Biochar supplementation significantly reduced CH 4 and N 2O fluxes and improved soil mineralization and physicochemical properties toward beneficial for rice plants. The results suggest that the optimal combination of biochar-application rates and effective water-irrigation techniques for soil types in the MD should be further studied in future works.

Rice husk and melaleuca biochar additions reduce soil CH 4 and N 2O emissions and increase soil physicochemical properties

Background: Biochar is a promising material in mitigating greenhouse gases (GHGs) emissions from paddy fields due to its remarkable structural properties. Rice husk biochar (RhB) and melaleuca biochar (MB) are amendment materials that could be used to potentially reduce emissions in the Vietnamese Mekong Delta (VMD). However, their effects on CH 4 and N 2O emissions and soil under local water management and conventional rice cultivation have not been thoroughly investigated. Methods: We conducted a field experiment using biochar additions to the topsoil layer (0-20 cm). Five treatments comprising 0 t ha -1 (CT0); 5 t ha -1 (RhB5) and 10 t ha -1 (RhB10), and 5 t ha -1 (MB5) and 10 t ha -1 (MB10) were designed plot-by-plot (20 m 2) in triplicates. Results: The results showed that biochar application from 5 to 10 t ha -1 significantly decreased cumulative CH 4 (24.2-28.0%, RhB; 22.0-14.1%, MB) and N 2O (25.6-41.0%, RhB; 38.4–56.4%, MB) fluxes without a reduction in grain yield. Increasing the biochar application rate further did not decrease significantly total CH 4 and N 2O fluxes but was seen to significantly reduce the global warming potential (GWP) and yield-scale GWP in the RhB treatments. Biochar application improved soil Eh but had no effects on soil pH. Whereas CH 4 flux correlated negatively with soil Eh ( P < 0.001; r 2 = 0.552, RhB; P < 0.001; r 2 = 0.502, MB). Ameliorating soil aeration and functions by adding RhB and MB resulted in improving soil physicochemical properties, especially significant SOM and AN boosting, which indicate better soil health, structure, and fertility. Conclusions: Biochar supplementation significantly reduced CH 4 and N 2O fluxes and improved soil mineralization and physicochemical properties toward beneficial for rice plants. The results suggest that the optimal combination of biochar-application rates and effective water-irrigation techniques for soil types in the MD should be further studied in future works.

Total ammonia and N&lt;SUB align="right"&gt;2O emission characteristics from &lt;i&gt;Alcaligenes&lt;/i&gt; sp. LS2T cultures and its application on laying hen manure associated with different pH conditions

Total ammonia and N&lt;SUB align="right"&gt;2O emission characteristics from &lt;i&gt;Alcaligenes&lt;/i&gt; sp. LS2T cultures and its application on laying hen manure associated with different pH conditions

Total ammonia and N&lt;SUB align="right"&gt;2O emission characteristics from &lt;i&gt;Alcaligenes&lt;/i&gt; sp. LS2T cultures and its application on laying hen manure associated with different pH conditions

The main objective of this research was to investigate the Alcaligenes sp. LS2T characteristics in total ammonia and N2O emission under different carbon sources and C/N ratios in the synthetic media. Observation of the strain application potential to suppress ammonia emission was also performed on laying hen manure with different initial pH conditions. The total ammonia concentration was observed by Nessler's reagent photometry method followed by Lide and Frederikse equation, while the N2O emission was measured by gas chromatography. The result showed that the least total ammonia concentration (12.77 ± 2.61 ppm) was seen in acetate C/N 28 medium. The highest N2O emission was seen in citrate C/N 14 medium, which emitted 377.13 ± 20.11 ppb N2O. The least emitted ammonia in the manure media was seen in an acid medium (116.92 ± 8.34 ppm ammonia). The results showed the Alcaligenes sp. LS2T capabilities to remove ammonia under aerobic condition.

Functional structures of soil microbial community relate to contrasting N2O emission patterns from a highly acidified forest

Nitrous oxide (N2O) is an important greenhouse gas contributing to global climate change. Emissions of N2O from acidic forests are increasing rapidly; however, little is known about the mechanisms driving these emissions. We analyzed soil samples from a high N2O emission area (HEA, 224–601 μg N m−2 h−1) and an adjacent low emission area (LEA, 20–30 μg N m−2 h−1) of a highly acidified forest. HEA showed similar carbon and nitrogen (N) pools and microbial biomass to LEA, but significantly higher moisture and extractable nutrients than LEA did. GeoChip 4 detected 298 gene families (unadjusted P < 0.05; 94, adjusted P < 0.05) showing significantly different structures between HEA and LEA. Both areas had highly diverse N cycling functional genes. However, HEA had higher relative abundances of nor, P450nor, and archaeal nitrifier nirK, which provided evidence for the importance of denitrifiers in N2O emission. HEA also showed significantly higher relative abundances of lignin- and cellulose-degrading genes, oxygen-limitation-response genes and denitrifier ppk, but lower abundances of N- and phosphorus (P) -limitation-response genes especially denitrifier pstS, corresponding to the higher moisture and extractable nutrients conducive to denitrification. The moisture, extractable nutrients and pH explained over 50% variation in microbial communities, and extractable P appeared as the key factor driving community variation and consequently regulated N2O production. Capsule abstractN2O emission in highly acidified forest soils was related to the diverse N functional genes, especially denitrification genes, and was affected by soil properties.

Study on model of greenhouse gas N&lt;SUB align="right"&gt;2O emission flux of rice field in cold region in growing season in water-saving irrigation mode

Under the condition of field experiment, three water management modes of control irrigation, intermittent irrigation and flood irrigation were set, a static black-box-gas chromatographic method was adopted for field in-situ observation on N2O emission flux of cold region rice field in the growing season, and optimal single-factor model and interaction model of N2O emission flux of rice in different water management modes in the growing season were established by using test data of 2014. The interaction model can effectively describe the response features of rice field N2O emission flux to soil nitrate nitrogen and temperature coordinated variation better than any single-factor model. The models of the study can be used for estimating N2O emission flux of rice field in the growing season in cold region of China.

S3-2-14 Nitrous oxide (N_2O) reducing denitrifiers inoculated into granular organic fertilizer mitigate N_2O emissions from soils

S3-2-14 Nitrous oxide (N_2O) reducing denitrifiers inoculated into granular organic fertilizer mitigate N_2O emissions from soils

3-2-6 Nitrous oxide (N_2O) reducing denitrifiers mitigate N_2O emission from soil and promote pasture growth

3-2-6 Nitrous oxide (N_2O) reducing denitrifiers mitigate N_2O emission from soil and promote pasture growth

Measurement and Modeling Nitrous Oxide Emissions from Ferric Luvisols in the Guinea Savanna Agro-ecological Zone of Ghana

Agricultural sector in Ghana contributes to about 60% of Gross Domestic Product (GDP) and is mainly characterized by fertilizer application to improve depleting soil fertility. With the increase in population and demand for increased productivity, application of inorganic fertilizers will result in enhanced greenhouse gas emissions. As nitrogen (N) is among the most limiting soil nutrient in the Guinea Savanna, chemical/organic fertilizers are applied in significant amounts to maintain crop productivity. Because of increased fertilizer and manure application to replenish dwindling soil fertility, the region is likely to become a significant source of nitrous oxide (N 2O) emissions. To study the effect of fertilizer application on N 2O emissions, Denitrification decomposition model (DNDC), a process-base model of carbon (C) and nitrogen (N) biogeochemistry in agricultural ecosystems was calibrated with field data obtained in 2013 and was used to predict the impact of N fertilizer source and rate of application on N 2O emissions. The linear equation between measured and modeled annual fluxes from ferric luvisols showed a

Water in star-forming regions withHerschel(WISH)(Corrigendum)

Context. Outflows are an important part of the star formation process as both the result of ongoing active accretion and one of the main sources of mechanical feedback on small scales. Water is the ideal tracer of these effects because it is present in high abundance for the conditions expected in various parts of the protostar, particularly the outflow. Aims. We constrain and quantify the physical conditions probed by water in the outflow-jet system for Class 0 and I sources. Methods. We present velocity-resolved Herschel HIFI spectra of multiple water-transitions observed towards 29 nearby Class 0/ Ip rotostars as part of the WISH guaranteed time key programme. The lines are decomposed into different Gaussian components, with each component related to one of three parts of the protostellar system; quiescent envelope, cavity shock and spot shocks in the jet and at the base of the outflow. We then use non-LTE radex models to constrain the excitation conditions present in the two outflow-related components. Results. Water emission at the source position is optically thick but effectively thin, with line ratios that do not vary with velocity, in contrast to CO. The physical conditions of the cavity and spot shocks are similar, with post-shock H2 densities of order 10 5 −10 8 cm −3 and H2O column densities of order 10 16 −10 18 cm −2 .H 2O emission originates in compact emitting regions: for the spot shocks these correspond to point sources with radii of order 10−200 AU, while for the cavity shocks these come from a thin layer along the outflow cavity wall with thickness of order 1−30 AU. Conclusions. Water emission at the source position traces two distinct kinematic components in the outflow; J shocks at the base of the outflow or in the jet, and C shocks in a thin layer in the cavity wall. The similarity of the physical conditions is in contrast to off-source determinations which show similar densities but lower column densities and larger filling factors. We propose that this is due to the differences in shock properties and geometry between these positions. Class I sources have similar excitation conditions to Class 0 sources, but generally smaller line-widths and emitting region sizes. We suggest that it is the velocity of the wind driving the outflow, rather than the decrease in envelope density or mass, that is the cause of the decrease in H2O intensity between Class 0 and I sources.

N_2O Emission in the Japanese pear production system through continuous application of swine manure compost for 10-years and analysis of the impact factor

N_2O Emission in the Japanese pear production system through continuous application of swine manure compost for 10-years and analysis of the impact factor

Sources of nitrous and nitric oxides in paddy soils: Nitrification and denitrification

Rice-paddies are regarded as one of the main agricultural sources of N 2O and NO emissions. To date, however, specific N2O and NO production pathways are poorly understood in paddy soils. 15N-tracing experiments were carried out to investigate the processes responsible for N2O and NO production in two paddy soils with substantially different soil properties. Laboratory incubation experiments were carried out under aerobic conditions at moisture contents corresponding to 60% of water holding capacity. The relative importance of nitrification and denitrification to the flux of N2O was quantified by periodically measuring and comparing the enrichments of the N2O, NH+4-N and NO−3-N pools. The results showed that both N2O and NO emission rates in an alkaline paddy soil with clayey texture were substantially higher than those in a neutral paddy soil with silty loamy texture. In accordance with most published results, the ammonium N pool was the main source of N2O emission across the soil profiles of the two paddy soils, being responsible for 59.7% to 97.7% of total N2O emissions. The NO−3-N pool of N2O emission was relatively less important under the given aerobic conditions. The rates of N2O emission from nitrification (N2On) among different soil layers were significantly different, which could be attributed to both the differences in gross N nitrification rates and to the ratios of nitrified N emitted as N2O among soil layers. Furthermore, NO fluxes were positively correlated with the changes in gross nitrification rates and the ratios of NO/N2O in the two paddy soils were always greater than one (from 1.26 to 6.47). We therefore deduce that, similar to N2O, nitrification was also the dominant source of NO in the tested paddy soils at water contents below 60% water holding capacity.

DIGIT survey of far-infrared lines from protoplanetary disks

[abridged] We present far-infrared spectroscopic observations of PMS stars taken with Herschel/PACS as part of the DIGIT key project. The sample includes 22 Herbig AeBe and 8 T Tauri sources. Multiple atomic fine structure and molecular lines are detected at the source position: [OI], [CII], CO, OH, H_2O, CH^+. The most common feature is the [OI] 63micron line detected in almost all of the sources followed by OH. In contrast with CO, OH is detected toward both Herbig AeBe groups (flared and non-flared sources). An isothermal LTE slab model fit to the OH lines indicates column densities of 10^13 < N_OH < 10^16 cm^-2, emitting radii 15 < r < 100 AU and excitation temperatures 100 < T_ex < 400 K. The OH emission thus comes from a warm layer in the disk at intermediate stellar distances. Warm H_2O emission is detected through multiple lines toward the T Tauri systems AS 205, DG Tau, S CrA and RNO 90 and three Herbig AeBe systems HD 104237, HD 142527, HD 163296 (through line stacking). Overall, Herbig AeBe sources have higher OH/H_2O abundance ratios across the disk than do T Tauri disks, from near- to far-infrared wavelengths. Far-infrared CH^+ emission is detected toward HD 100546 and HD 97048. The slab model suggests moderate excitation (T_ex ~ 100 K) and compact (r ~ 60 AU) emission in the case of HD 100546. The [CII] emission is spatially extended in all sources where the line is detected. This suggests that not all [CII] emission is associated with the disk and that there is a substantial contribution from diffuse material around the young stars. The flux ratios of the atomic fine structure lines are consistent with a disk origin for the oxygen lines for most of the sources.

Estimate of N_2O emission of hog and poultry manure compost from amount of acid detergent soluble nitrogen

Estimate of N_2O emission of hog and poultry manure compost from amount of acid detergent soluble nitrogen

Greenhouse gas emissions and the role of the Kyoto Protocol

Our study empirically investigates the effects of the Kyoto Protocol’s quantified emission limitation or reduction commitments on various greenhouse gas (GHG) emissions such as CO2, CH4, N2O and other greenhouse gases, consisting of HFCs, PFCs and SF6. These GHG emissions are considered to be the main source of global warming issues and 39 countries approved to meet the commitments by ratifying the Kyoto Protocol. Our empirical analysis is based on the STIRPAT model, the stochastic version of the IPAT model, using the data of 119 countries in 1990, 1995, 2000 and 2005. Our main findings are that the effects of the commitments to the Kyoto Protocol (1) are significantly negative for the cases of CO2 and CH4 emissions, (2) are not significant for the case of N 2O emissions and (3) are significantly positive for the case of other greenhouse gas emissions. These results have important policy implications for global warming issues.

Emission of greenhouse gases from controlled incineration of cattle manure

Greenhouse gas emission is a potential limiting factor in livestock farming development. While incineration is one approach to minimize livestock manure, there are concerns about significant levels of nitrogen and organic compounds in manure as potential sources of greenhouse gas emissions (N 2O and CH 4). In this study, the effects of various incineration conditions, such as the furnace temperature and air ratio on N 2O and CH 4 formation behaviour, of cattle manure (as a representative livestock manure) were investigated in a pilot rotary kiln furnace. The results revealed that N 2O emissions decreased with increasing temperature and decreasing air ratio. In addition, CH 4 emissions tended to be high above 800 °C at a low air ratio. The emission factors for N 2O and CH 4 under the general conditions (combustion temperature of 800–850 °C and air ratio of 1.4) were determined to be 1.9–6.0% g-N 2O -N/g-N and 0.0046–0.26% g-CH 4/g -burning object, respectively. The emission factor for CH 4 differed slightly from the published values between 0.16 and 0.38% g-CH 4/g -burning object. However, the emission factor for N 2O was much higher than the currently accepted value of 0.7% g-N 2O -N/g-N and, therefore, it is necessary to revise the N 2O emission factor for the incineration of livestock manure.

Effect of cattle diet and manure storage conditions on carbon dioxide, methane and nitrous oxide emissions from tie-stall barns and stored solid manure

The diversity of beef cattle production systems in terms of diet, manure management and building design results in variation in greenhouse gas (GHG) emissions and the opportunities to reduce them. Within this context, we studied the effect of the varying proportions of concentrate (37–85% of DM) in the diet of Belgian Blue heifers on CH 4 and N 2O emissions from a tie-stall system (barn and solid manure storage). Trials were conducted over two consecutive periods in which manure was stored mainly in winter and spring. Increasing the proportions of concentrate in the diet reduced the GHG (CH 4 + N 2O) emissions from the barns from 8.5 ± 1.6 to 1.9 ± 0.4 kg CO 2 eq/kg live-weight gain, but had not significant influence on the emissions from the stored solid manure. Seasonal variation in gas emissions was observed, with lower emissions from stored solid manure in winter than in spring (159 ± 25 and 314 ± 49 mg CO 2, 0.14 ± 0.02 and 2.47 ± 0.78 mg CH 4, and <0.01 and 0.24 ± 0.09 mg N 2O/kg of fresh manure stored/d of storage, respectively), indicating that manure storage in the warmer season should be avoided. The GHG (CH 4 + N 2O) emissions from stored solid manure, however, were less than 11% of the total emissions (barns + manure storage). The emphasis in these systems should therefore be on modelling and reducing direct CH 4 emissions from cattle but feed production impact should also be included. The GHG emissions were validated using nutrient (C, K, P and ash) balances including CO 2 and CH 4 emissions for the C balance.

Nitrous oxide emissions from a maize field during two consecutive growing seasons in the North China Plain

Abstract Nitrous oxide (N 2O) emissions from a maize field in the North China Plain (Wangdu County, Hebei Province, China) were investigated using static chambers during two consecutive maize growing seasons in the 2008 and 2009. The N 2O pulse emissions occurred with duration of about 10 days after basal and additional fertilizer applications in the both years. The average N 2O fluxes from the CK (control plot, without crop, fertilization and irrigation), NP (chemical N fertilizer), SN (wheat straw returning plus chemical N fertilizer), OM-1/2N (chicken manure plus half chemical N fertilizer) and OMN (chicken manure plus chemical N fertilizer) plots in 2008 were 8.51, 72.1, 76.6, 101, 107 ng N/(m 2·sec), respectively, and in 2009 were 33.7, 30.0 and 35.0 ng N/(m 2·sec) from CK, NP and SN plots, respectively. The emission factors of the applied fertilizer as N2O-N (EFs) were 3.8% (2008) and 1.1% (2009) for the NP plot, 3.2% (2008) and 1.2% (2009) for the SN plot, and 2.8% and 2.2% in 2008 for the OM-1/2N and OMN plots, respectively. Hydromorphic properties of the investigated soil (with gley) are in favor of denitrification. The large differences of the soil temperature and water-filled pore space (WFPS) between the two maize seasons were suspected to be responsible for the significant yearly variations. Compared with the treatments of NP and SN, chicken manure coupled with compound fertilizer application significantly reduced fertilizer loss rate as N 2O-N.

Nitrous Oxide Emissions from Fields with Different Wheat and Rice Varieties

Plant species of cropping systems may affect nitrous oxide (N 2O) emissions. A field experiment was conducted to investigate dynamics of N 2 O emissions from rice-wheat fields from December 2006 to June 2007 and the relationships of soil and plant parameters with N 2O emissions. The results indicated that N 2O emissions from different wheat varieties ranged from 12 to 291 μg N 2O-N m −2 h −1 and seasonal N 2O emissions ranged from 312 to 385 mg N 2O-N m −2. In the rice season, it was from 11 to 154 μg N 2O-N m −2 h −1 with seasonal N 2O emission of 190–216 mg N 2O-N m −2. The seasonal integrated flux of N 2O differed significantly among wheat and rice varieties. The wheat variety HUW 234 and rice variety Joymoti showed higher seasonal N 2O emissions. In the wheat season, N 2O emissions correlated with soil organic carbon (SOC), soil NO − 3-N, soil temperature, shoot dry weight, and root dry weight. Among the variables assessed, soil temperature followed by SOC and soil NO − 3-N were considered as the important variables influencing N 2O emission. N 2O emission in the rice season was significantly correlated with SOC, soil NO − 3-N, soil temperature, leaf area, shoot dry weight, and root dry weight. The main driving forces influencing N 2O emission in the rice season were soil NO − 3-N, leaf area, and SOC.

Changes in carbon stock and greenhouse gas balance in a coffee ( Coffea arabica) monoculture versus an agroforestry system with Inga densiflora, in Costa Rica

Agroforestry represents an opportunity to reduce CO 2 concentrations in the atmosphere by increasing carbon (C) stocks in agricultural lands. Agroforestry practices may also promote mineral N fertilization and the use of N 2-fixing legumes that favor the emission of non-CO 2 greenhouse gases (GHG) (N 2O and CH 4). The present study evaluates the net GHG balance in two adjacent coffee plantations, both highly fertilized (250 kg N ha −1 year −1): a monoculture (CM) and a culture shaded by the N 2-fixing legume tree species Inga densiflora (CIn). C stocks, soil N 2O emissions and CH 4 uptakes were measured during the first cycle of both plantations. During a 3-year period (6–9 years after the establishment of the systems), soil C in the upper 10 cm remained constant in the CIn plantation (+0.09 ± 0.58 Mg C ha −1 year −1) and decreased slightly but not significantly in the CM plantation (−0.43 ± 0.53 Mg C ha −1 year −1). Aboveground carbon stocks in the coffee monoculture and the agroforestry system amounted to 9.8 ± 0.4 and 25.2 ± 0.6 Mg C ha −1, respectively, at 7 years after establishment. C storage rate in the phytomass was more than twice as large in the CIn compared to the CM system (4.6 ± 0.1 and 2.0 ± 0.1 Mg C ha −1 year −1, respectively). Annual soil N 2O emissions were 1.3 times larger in the CIn than in the CM plantation (5.8 ± 0.5 and 4.3 ± 0.3 kg N-N 2O ha −1 year −1, respectively). The net GHG balance at the soil scale calculated from the changes in soil C stocks and N 2O emissions, expressed in CO 2 equivalent, was negative in both coffee plantations indicating that the soil was a net source of GHG. Nevertheless this balance was in favor of the agroforestry system. The net GHG balance at the plantation scale, which includes additionally C storage in the phytomass, was positive and about 4 times larger in the CIn (14.59 ± 2.20 Mg CO 2 eq ha −1 year −1) than in the CM plantation (3.83 ± 1.98 Mg CO 2 eq ha −1 year −1). Thus converting the coffee monoculture to the coffee agroforestry plantation shaded by the N 2-fixing tree species I. densiflora would increase net atmospheric GHG removals by 10.76 ± 2.96 Mg CO 2 eq ha −1 year −1 during the first cycle of 8–9 years.