Reduction Of Nitrous Oxide Emissions Research Articles

Nitrous oxide emission reduction with greenwaste biochar: comparison of laboratory and field experiments

SummaryWe compared (i) nitrous oxide (N2O) fluxes from a 9‐month field experiment established on a temperate, newly sown, intensively managed meadow using automated chambers with fine time resolution, and (ii) fluxes measured at several occasions throughout the experiment under controlled laboratory conditions. Twenty tonnes dry matter ha−1 greenwaste biochar were added to three plots and compared with three control plots. Cumulated N2O field measurements revealed a reduction of 21.5% in the plots with biochar. The reductions for samples where the biochar was added at the beginning of the experiment in the field and samples which were collected each month and measured in the laboratory were in the same range (11.4–39.2%). Emission reductions from laboratory incubations when biochar was freshly mixed with soil in the laboratory were about twice as large (46.5–58.0%). Our results indicate provisionally that, at our site, biochar controls N2O emission through its capacity for reducing NO3− availability to denitrifiers, with the efficiency being related to the effectiveness of mixing of biochar in soil.

Combustion and performance of a diesel engine with preheated Jatropha curcas oil using waste heat from exhaust gas

The viscosity and density of CJO (crude Jatropha oil) were reduced by heating it using the heat from exhaust gas of a diesel engine with an appropriately designed helical coil heat exchanger. Experiments were conducted to evaluate the combustion characteristics of a DI (direct injection) diesel engine using PJO (preheated Jatropha oil). It exhibited a marginally higher cylinder gas pressure, rate of pressure rise and heat release rate as compared to HSD (high speed diesel) during the initial stages of combustion for all engine loadings. Ignition delay was shorter for PJO as compared to HSD. The results also indicated that BSFC (brake specific fuel consumption) and EGT (exhaust gas temperature) increased while BTE (brake thermal efficiency) decreased with PJO as compared to HSD for all engine loadings. The reductions in CO2 (carbon dioxide), HC (hydrocarbon) and NOx (nitrous oxide) emissions were observed for PJO along with increased CO (carbon monoxide) emission as compared to those of HSD.

Quantifying the Effects of Green Waste Compost Application, Water Content and Nitrogen Fertilization on Nitrous Oxide Emissions in 10 Agricultural Soils

Common management practices, such as the application of green waste compost, soil moisture manipulation, and nitrogen fertilization, affect nitrous oxide (NO) emissions from agricultural soils. To expand our understanding of how soils interact with these controls, we studied their effects in 10 agricultural soils. Application of compost slightly increased NO emissions in soils with low initial levels of inorganic N and low background emission. For soils in which compost caused a decrease in emission, this decrease was larger than any of the observed increases in the other soils. The five most important factors driving emission across all soils, in order of increasing importance, were native dissolved organic carbon (DOC), treatment-induced change in DOC, native inorganic N, change in pH, and soil iron (Fe). Notable was the prominence of Fe as a regulator of NO emission. In general, compost is a viable amendment, considering the agronomic benefits it provides against the risk of producing a small increase in NO emissions. However, if soil properties and conditions are taken into account, management can recognize the potential effect of compost and thereby reduce NO emissions from susceptible soils, particularly by avoiding application of compost under wet conditions and together with ammonium fertilizer.

Nitrogen Source and Placement Effects on Soil Nitrous Oxide Emissions from No‐Till Corn

A nitrogen (N) source comparison study was conducted to further evaluate the effects of inorganic N source and placement on growing-season and non-crop period soil nitrous oxide (NO). Commercially available controlled-release N fertilizers were evaluated for their potential to reduce NO emissions from a clay loam soil compared with conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated no-till (NT) corn ( L.) production system. Controlled-release N fertilizers evaluated were: a polymer-coated urea (ESN), stabilized urea (SuperU), and UAN+AgrotainPlus (SuperU and AgrotainPlus contain nitrification and urease inhibitors). Each N source was surface band applied (202 kg N ha) near the corn row at emergence and watered into the soil the next day. Subsurface banded ESN (ESNssb) and check (no N applied) treatments were included. Nitrous oxide fluxes were measured during two growing seasons and after harvest using static, vented chambers. All N sources had significantly lower growing-season NO emissions than granular urea (0.7% of applied N), with UAN+AgrotainPlus (0.2% of applied N) and ESN (0.3% of applied N) having lower emissions than UAN (0.4% of applied N). Similar trends were observed when expressing NO emissions on a grain yield and N uptake basis. Corn grain yields were not different among N sources but were greater than the check. Selection of N fertilizer source can be a mitigation practice for reducing NO emissions in NT, irrigated corn in semiarid areas. In our study, UAN+AgrotainPlus consistently had the lowest level of NO emissions with no yield loss.

Reducing greenhouse gas emissions from livestock

Methane production is lower from ruminants given diets which produce less acetate and more propionate. This means using diets higher in starch and lower in fibre. There are implications of this feeding strategy for animal health. Reducing the concentration of N in the animal’s diet is likely to lead to a reduction in nitrous oxide emissions. Both methane per kg product and the percentage of dietary N which is converted into N in animal products are influenced strongly by the level of animal output. Improving feed conversion ratio and nitrogen use efficiency should result in reduced greenhouse gas emissions from livestock.

Nitrous oxide emissions from the oxidation tank of a pilot activated sludge plant

This study discusses the results of the continuous monitoring of nitrous oxide emissions from the oxidation tank of a pilot conventional wastewater treatment plant. Nitrous oxide emissions from biological processes for nitrogen removal in wastewater treatment plants have drawn great attention over the last years, due to the high greenhouse effect. However, even if several studies have been carried out to quantify nitrous oxide emission rates from different types of treatment, quite wide ranges have been reported. Only grab samples or continuous measurements over limited periods were considered in previous studies, which can account for the wide variability of the obtained results. Through continuous monitoring over several months, our work tries to fill this gap of knowledge and get a deeper insight into nitrous oxide daily and weekly emission dynamics. Moreover, the influence of some operating conditions (sludge age, dissolved oxygen concentration in the oxidation tank, nitrogen load) was studied to determine good practices for wastewater treatment plant operation aiming at the reduction of nitrous oxide emissions. The dissolved oxygen set-point is shown to play a major role in nitrous oxide emissions. Low sludge ages and high nitrogen loads are responsible for higher emissions as well. An interesting pattern has been observed, with quite negligible emissions during most of the day and a peak with a bell-like shape in the morning in the hours of maximum nitrogen load in the plant, correlated to the ammonia and nitrite peaks in the tank.

Nitrogen Source Effects on Soil Nitrous Oxide Emissions from Strip‐Till Corn

Nitrogen (N) application to crops generally results in increased nitrous oxide (NO) emissions. Commercially available, enhanced-efficiency N fertilizers were evaluated for their potential to reduce NO emissions from a clay loam soil compared with conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated strip-till (ST) corn ( L.) production system. Enhanced-efficiency N fertilizers evaluated were a controlled-release, polymer-coated urea (ESN), stabilized urea, and UAN products containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus), and UAN containing a slow-release N source (Nfusion). Each N source was surface-band applied (202 kg N ha) at corn emergence and watered into the soil the next day. A subsurface-band ESN treatment was included. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. All N sources had significantly lower growing season NO emissions than granular urea, with UAN+AgrotainPlus and UAN+Nfusion having lower emissions than UAN. Similar trends were observed when expressing NO emissions on a grain yield and N uptake basis. Loss of NO-N per kilogram of N applied was <0.8% for all N sources. Corn grain yields were not different among N sources but greater than treatments with no N applied. Selection of N fertilizer source can be a mitigation practice for reducing NO emissions in strip-till, irrigated corn in semiarid areas.

Broadcast Urea Reduces N2O but Increases NO Emissions Compared with Conventional and Shallow‐Applied Anhydrous Ammonia in a Coarse‐Textured Soil

Despite the importance of anhydrous ammonia (AA) and urea as nitrogen (N) fertilizer sources in the United States, there have been few direct comparisons of their effects on soil nitrous oxide (NO) and nitric oxide (NO) emissions. We compared N oxide emissions, yields, and N fertilizer recovery efficiency (NFRE) in a corn ( L.) production system that used three different fertilizer practices: urea that was broadcast and incorporated (BU) and AA that was injected at a conventional depth (0.20 m) (AAc) and at a shallower depth (0.10 m) (AAs). Averaged over 2 yr in an irrigated loamy sand in Minnesota, growing season NO emissions increased in the order BU < AAc < AAs. In contrast, NO emissions were greater with BU than with AAc or AAs. Emissions of NO ranged from 0.5 to 1.4 kg N ha (50-140 g N Mg grain), while NO emissions ranged from 0.2 to 0.7 kg N ha (20-70 g N Mg grain). Emissions of total N oxides (NO + NO) increased in the order AAc < BU < AAs. Despite having the greatest emissions of NO and total N oxides, the AAs treatment had greater NFRE compared with the AAc treatment. These results provide additional evidence that AA emits more NO, but less NO, than broadcast urea and show that practices to reduce NO emissions do not always improve N use efficiency.

High-sugar grasses.

Abstract Perennial ryegrass diploids with elevated concentrations of water-soluble carbohydrate (WSC), commonly termed 'high-sugar grasses' (HSGs), have been promoted as a tool for increasing the efficiency of the use of protein (nitrogen (N)) in the rumen and thus offering scope for increasing milk production and animal growth rates, while reducing N losses (in the form of urine) to the environment. Much controversy has arisen about efficacy, largely because benefits have not been seen in all trials, and partly because of variation in the degree to which the sugar trait has been present, or expressed, in several cases reflecting gene × environment or gene × management interactions. Combining the data from multiple trials shows that there is a continuum of response in N-use efficiency (NUE) to WSC:crude protein (CP) ratio, and so 'proof of concept' has been shown. A considerable amount of research is still required to demonstrate a consistently high expression of the trait, and to demonstrate reliably the potential for yield gains and reduced N loss. Associated reductions in nitrous oxide emissions (a potent greenhouse gas (GHG)) are yet to be confirmed. Even more uncertain is the prospect for reducing methane emissions, whether per hectare or per unit energy intake or animal product. Nonetheless, there has been a determined effort to pursue this trait, and to confirm the long-standing hypothesis for NUE. There is no basis as yet for dismissing the prospects of success. The trait remains one of very few low-cost tools being investigated for its potential to mitigate the environmental footprint of livestock production.

Field-scale verification of nitrous oxide emission reduction with DCD in dairy-grazed pasture using measurements and modelling

Nitrous oxide (N2O) from agricultural soils is a major source of greenhouse gas emissions in New Zealand. Nitrification inhibitors are seen as a potential technology to reduce these N2O emissions from agricultural soils. In previous studies on the effect of dicyandiamide (DCD) on N2O emissions from animal excreta, DCD was directly applied to urine. However, farmers apply DCD to grazed pastures shortly before or after grazing rather than applying it specifically to the urine patches. Accordingly, the objectives of this study were: (1) to test, using chamber measurements, whether the same level of N2O reduction is achieved under grazed conditions where excretal N is non-uniformly deposited, (2) to apply the process-based NZ-DNDC model to simulate the effect of DCD on emission reductions, and (3) to perform a sensitivity analysis on the NZ-DNDC model to investigate how uncertainties in the input parameters affect the modelled N2O emissions. Two circular 1260-m2 treatment plots were grazed simultaneously for 5 h, by 20 cattle on each plot. The following day, DCD was applied in 800 L of water to one of the plots at 10 kg/ha and N2O emissions were measured periodically for 20 days. The cumulative N2O emissions were 220 ± 90 and 110 ± 20 g N2O-N/ha for the untreated and DCD-treated plots, respectively (based on the arithmetic mean and standard error of the chambers). This suggests a reduction in N2O emission from DCD application of ~50 ± 40% from a single grazing event. However, this result should be treated with caution because the possibility of sampling error due to the chamber distribution cannot be excluded. NZ-DNDC simulated N2O emissions of 169 and 68 g N2O-N/ha for the untreated and DCD-treated areas, respectively, corresponding to a reduction of 60% in N2O emissions from DCD application. This level of reduction is consistent with that found in experiments with individual urine patches. N2O emissions found through use of NZ-DNDC were sensitive to uncertainties in the input parameters. The combined effect of varying the initial soil NO3– and NH4+, soil moisture, soil organic carbon, bulk density, clay content, pH, and water-filled pore-space at field capacity inputs within plausible ranges was to change the simulated N2O emissions by –87% to +150%.

Potential of Aerobic Denitrification by Pseudomonas stutzeri TR2 To Reduce Nitrous Oxide Emissions from Wastewater Treatment Plants

In contrast to most denitrifiers studied so far, Pseudomonas stutzeri TR2 produces low levels of nitrous oxide (N(2)O) even under aerobic conditions. We compared the denitrification activity of strain TR2 with those of various denitrifiers in an artificial medium that was derived from piggery wastewater. Strain TR2 exhibited strong denitrification activity and produced little N(2)O under all conditions tested. Its growth rate under denitrifying conditions was near comparable to that under aerobic conditions, showing a sharp contrast to the lower growth rates of other denitrifiers under denitrifying conditions. Strain TR2 was tolerant to toxic nitrite, even utilizing it as a good denitrification substrate. When both nitrite and N(2)O were present, strain TR2 reduced N(2)O in preference to nitrite as the denitrification substrate. This bacterial strain was readily able to adapt to denitrifying conditions by expressing the denitrification genes for cytochrome cd(1) nitrite reductase (NiR) (nirS) and nitrous oxide reductase (NoS) (nosZ). Interestingly, nosZ was constitutively expressed even under nondenitrifying, aerobic conditions, consistent with our finding that strain TR2 preferred N(2)O to nitrite. These properties of strain TR2 concerning denitrification are in sharp contrast to those of well-characterized denitrifiers. These results demonstrate that some bacterial species, such as strain TR2, have adopted a strategy for survival by preferring denitrification to oxygen respiration. The bacterium was also shown to contain the potential to reduce N(2)O emissions when applied to sewage disposal fields.

Management of Native Soil Nitrogen for Reducing Nitrous Oxide Emissions and Higher Rice Production

Present production of rice is far below its reported potential yield because of being Ndeficiency, the major constraint. Because of poverty, small farmers have to rely on native soil N-supply. Between wheat harvest and rice transplanting, a dry-to-wet season transition (DWT) period exist with changing soil moisture from aerobic to anaerobic and a large amount of native soil N loss is hypothesized. To study soil N dynamism and possible management options for DWT, two years field experiments were conducted in Chitwan with four land management treatments like bare fallow, mucuna, mungbean and maize. Treatments were randomly allotted in 10 m&lt;sup&gt;2&lt;/sup&gt; plots. During DWT, building up of 50-75 kg of nitrate-N was observed at 60-75 % field capacity (FC) soil moisture but lost after flooding through leaching and denitrification, resulting in low grain yield and N uptake of succeeding rice. Growing cover crops during DWT, reduced leaching loss by half and N2O emissions by two thirds of those in the bare fallows. Atmospheric-N addition by legumes ranged from 27 to 56 kg ha-1 depending on the types of legumes and increased N uptake and grain yield by 24-42 kg N ha-1 yr-1 and 1.2-2.1 Mg ha-1 yr-1respectively. Thus, cultivation of grain/green manure legumes appears economically and ecologically beneficial.Key Words: bare fallow, crop N uptake, denitrification, green manure, leaching, nitrate catch crops, nitrificationThe Journal of Agriculture and Environment Vol:9, Jun.2008 Page: 1-9

Multi-Gas Emission Reduction for Climate Change Policy: An Application of Fund

The costs of greenhouse gas emission reduction with abatement of carbon dioxide, methane, and nitrous oxide are investigated using the FUND model. The central policy scenario keeps anthropogenic radiative forcing below 4.5 Wm2. If CO2 emission reduction were the only possibility to meet this target, the net present value of consumption losses would be $45 trillion; with abatement of the other gases added, costs fall to $33 trillion. The bulk of these costs savings can be ascribed to reductions of nitrous oxide. Because nitrous oxide emission reduction is so much more important than methane emission reduction, the choice of equivalence metric between the greenhouse gases does not matter much. Sensitivity analyses show that the shape of the cost curves for CH4 and N2O emission reductions matter, and that the inclusion of sulphate aerosols makes policy targets substantially harder to achieve. The costs of emission reduction vary greatly with the choice of stabilisation target. A target of 4.5 Wm-2 is not justified by our current knowledge of the damage costs of climate change.

MEAD: An interdisciplinary study of the marine effects of atmospheric deposition in the Kattegat

This paper summarises the results of the EU funded MEAD project, an interdisciplinary study of the effects of atmospheric nitrogen deposition on the Kattegat Sea between Denmark and Sweden. The study considers emissions of reactive nitrogen gases, their transport, transformations, deposition and effects on algal growth together with management options to reduce these effects. We conclude that atmospheric deposition is an important source of fixed nitrogen to the region particularly in summer, when nitrogen is the limiting nutrient for phytoplankton growth, and contributes to the overall eutrophication pressures in this region. However, we also conclude that it is unlikely that atmospheric deposition can, on its own, induce algal blooms in this region. A reduction of atmospheric nitrogen loads to this region will require strategies to reduce emissions of ammonia from local agriculture and Europe wide reductions in nitrous oxide emissions.

Ecology of tree intercropping systems in the North temperate region: Experiences from southern Ontario, Canada

Agroforestry practices in northern latitudes, although less diverse than those in warmer regions, have unique advantages over conventional land-use systems in the region in terms of water-quality enhancement, carbon se-questration, and biodiversity conservation. Tree intercropping, especially, is a potentially promising agroforestry option in the region. Understanding the ecological interactions between trees and crops in such intercropped systems provides the basis for designing efficient systems with potential for wider applicability. With this objective, the experience from several years of research on this aspect at the University of Guelph, in southern Ontario, Canada are presented. Yields of C3 crops intercropped with trees, as well as growth of trees, did not differ from those in corresponding sole-stand (conventional) systems of crops and trees. But, soil organic carbon content and bird and insect diversity increased in the intercropped area. The abundance and distribution of earthworms were higher closer to the tree rows indicating improved soil health. The C sequestration potential in fast-growing tree (hybrid-poplar)-based intercropping systems was four times more than that reported for conventional agricultural fields in the region. Because of reduced fertilizer use and more efficient N-cycling, the tree-intercropping systems could also lead to the reduction of nitrous oxide emissions from agricultural fields by about 0.7 kg ha−1 yr−1. Marginal or degraded land that is suitable for agroforestry is estimated to be 57 million ha in Canada. Tree/crop intercropping is one agroforestry system that shows great potential for this region. We suggest that this land-management option can be placed above conventional agriculture in terms of long term-productivity and sustainability.

Reduction of Nitrous Oxide Emissions from Nitric Acid Plants

Reduction of Nitrous Oxide Emissions from Nitric Acid Plants

Environmental scenarios for the future nitrogen policy in Flanders, Belgium.

The agricultural sector accounts for two thirds of nitrogen losses in Flanders, Belgium. Since 1991 both the government and the farmers have been taking measures to reduce the nitrogen surplus. Initially, the manure policy was aimed at distributing the manure surplus equally across Flanders. At the same time, the growth of livestock was stopped by a strict licensing policy, which required “command and control” measures. In recent years, the policy has switched to the use of individual target commitments by farmers. The Flemish manure policy will be tightened even more as a result of international pressures. An ex ante evaluation of possible policy options was carried out using three different scenarios spread out until 2010 (Business As Usual, Additional Measures, and Sustainable Development). To do this, a sector-economic, regionalized, environmental, comparative static, partial equilibrium, mathematical programming model of the Flemish agriculture was developed. The nitrogen emission into the agricultural soil was calculated by means of a regional soil balance. European targets can only be reached with manure processing, reduced fertilizer usage, and a strong reduction of intensive livestock breeding activities. The atmospheric deposition of nitrogen compounds will strongly decrease in 2010 if additional measures are taken. This will also result in a strong reduction of nitrous oxide emissions.

Application and Use of Fertilizers for the Reduction of Nitrous Oxide Emissions from Upland Soils

Application and Use of Fertilizers for the Reduction of Nitrous Oxide Emissions from Upland Soils

Methods for reducing the emission of nitrous oxide from fluidized bed combustion

Two methods for the reduction of nitrous oxide emissions, afterburning and reversed air staging, are investigated in a 12 MW circulating fluidized bed boiler. With afterburning the N 2O emission can be reduced by 90% or more, using an amount of secondary fuel corresponding to 10% of the total energy input. With reversed air staging it is possible to reduce the emission of N 2O to one fourth (25 ppm), without significantly affecting the other emissions. With reversed air staging no secondary air is used in the combustor and an air-ratio of about unity is maintained throughout the combustion chamber. Air for final combustion is added in the cyclone outlet.

Effectiveness of non-CO2 greenhouse gas emission reduction technologies

Non-CO2 greenhouse gases, such as methane and nitrous oxide, can make a relevant contribution to the enhanced greenhouse effect, and hence emission reduction is desirable. In emission reduction inventories, both the magnitude of the emission reduction as well as the specific emission reduction costs should be determined. The current knowledge of the potential for and costs of reducing these emissions is still limited. Taking this into account, the following results can be obtained. Methane emissions can be considerably reduced from underground coal mining, oil production, natural gas operations, landfilling of waste, and wastewater treatment. Also emissions from enteric fermentation and animal manure can be reduced substantially. The total technical potential for methane emission reduction (given the present activity level) is estimated to be about one third. The economic potential, having net negative emission reduction costs, is estimated to be about half of this value. These reductions can be attained over a period of 10 - 20 years. The technical potential for the reduction of nitrous oxide emissions is currently estimated to be less than 10% Apart from the possibility of implementing existing techniques, there seems to be considerable room for developing techniques for more far-reaching emission reductions both for methane and nitrous oxide.