Nitrogen Emissions Research Articles

High efficiency and low greenhouse gas emissions intensity of maize in drip irrigation under mulch system

It is the goal of agricultural development to achieve the comprehensive benefits of high yield, high water and nitrogen efficiency but low environmental damage. However, the comprehensive benefits of greenhouse gas (GHG) emissions, grain yield, water and fertilizer efficiency in fertilized fields with different film mulching irrigation remain unclear. Therefore, we conducted typical maize field observation experiments based on drip irrigation under mulch (DM) and border irrigation under mulch (BM) for three years to quantify GHG emissions and their influencing factors, and analyzed maize yield, irrigation water use efficiency (IWUE), partial factor productivity of applied nitrogen (PFPN) and greenhouse gas emission intensity (GHGI). In our experiment, N2O emissions were lower by 32.46%, CH4 absorption was higher by 23.49%, and CO2 emissions were lower by 4.53% under DM than under BM. The roles of different environmental factors in controlling GHG fluxes were different under two treatments. The relative importance of soil NO3−−N content to N2O and CH4 fluxes under DM was the greatest, and the values were 0.61 and 0.47, respectively. The soil NH4+−N content had the greatest relative importance to CO2 flux under DM (0.43), CH4 flux under BM (0.72), and CO2 flux under BM (0.52). In addition, the maize yield, IWUE and PFPN under DM were 17.85%, 17.90% and 71.84% higher than those under BM, while the global warming potential (GWP) and GHGI under DM were 6.65% and 20.79% lower than those under BM, respectively. Our research provides a more comprehensive understanding of typical farmland management practices in arid areas and has important implications for agricultural development.

NOX Concentration Prediction in Cement Denitrification Process Based on EEMD-MImRMR-BASBP

NOx concentration is an important indicator of the response to ammonia dosage and nitrogen emissions, and its accurate prediction allows for efficient and rational optimal control of ammonia dosage. Due to the large external noise, time lag and non-linearity of the cement denitrification process, it is difficult to derive accurate mathematical prediction models. Therefore, a new machine learning model, namely EEMD-MImRMR-BASBP, is developed. Firstly, Ensemble Empirical Mode Decomposition (EEMD) and median-averaged filtering is used to process the data and remove the noise. In order to handle the large time lags, non-linearity and non-smoothness among the variables, mutual information (MI) based on the entropy principle is proposed to calculate the lag time of the non-linear system; furthermore, according to the feature variable selection method of Max-Relevance and Min-Redundancy (mRMR), the factors with strong influence are selected as the input variables of the prediction model in combination with the results of the mechanism analysis. Then, the EEMD-MImRMR-BASBP model to predict NOX concentration is constructed, in which the initialization parameters of the Back Propagation Neural Network (BP) are searched by Beetle Antennae Search (BAS) to effectively overcome the parameter selection problem of traditional BP prediction models. Finally, the model was applied for the NOX concentration prediction of a real cement plant in Jiang xi and Fu ping and compared with the classical BP-based prediction model, BASBP model, the root means square error (RMSE) and mean absolute error (MAE) of the EEMD-MImRMR-BASBP model for the two production lines are only 0.2927, 0.3513 and 0.1795, and 0.2383, which have better prediction performance compared with the current model.

Accounting for the nitrogen footprint of food production in Chinese provinces during 1998–2018

Excessive emission of reactive nitrogen (Nr) in the environment has a negative impact on human health and biodiversity and aggravates the greenhouse effect. Food production and consumption is the primary source of anthropogenic Nr emissions. Currently, the research on China's nitrogen footprint lacks the exploration of regional differentiation, and the local virtual Nitrogen factor (VNF) is also insufficient. In this study, we developed localized VNF at the provincial level in China and then applied them to measure the per capita food production Nitrogen footprint of 31 provinces in mainland China from 1998 to 2018 by employing a modified N-Calculator model. We found that the national per capita food production N footprint varied from 15.30 to 21.09 kg/year over the past 20 years. Per capita food production N footprint of 29 provinces increased, ranging from 13% to 113%. The dominance of the food production N footprint of meat gradually increased, and the differences between regions showed a decreasing trend. Finally, we compared the results with different countries based on VNF and 2018 food consumption data. Although the limitations of the underlying data and parameters pose challenges to the accuracy of the estimation, our study provides an original data contribution to nitrogen footprint research to scientific communities and policymakers.

Use of response surface methodology approach for development of sustainable Jojoba biodiesel diesel blend with CuO nanoparticles for four stroke diesel engine

This study focuses primarily on the optimization of performance parameters, namely Brake thermal efficiency (BTE), Brake power (BP) and emission characteristics, namely Hydrocarbon (HC), carbon monoxide (CO) and oxides of nitrogen (NOX) emissions of a diesel engine fuelled with jojoba biodiesel-diesel blend with copper oxide (CuO) nanoparticles dispersed into it with different concentrations of 25, 50, 75 and 100 ppm. Variables such as blend (%), nanoparticles concentration (ppm), fuel injection pressure (bar) and Load (kg) are considered as input parameters. A series of experiments are designed under the central composite rotatable design (CCRD) approach considering 4 input factors each with 5 levels. A nonlinear RSM model is developed between the response and input variables based on the interaction plots. The model is validated by regression coefficient of R2, Adj. R2and Pred. R2which shows satisfactory results.Based on the desirability approach the model retrieve the best combination of input factors as 7.45 kg engine load, 16.76 % mixing of jojoba biodiesel with diesel, 209.89 bar fuel injection pressure, and CuO nanoparticles concentration of 76.76 ppm. After RSM optimization, target values of engine responses (BTE, BP, CO, HC, and NOx) are 27.18 %, 2.5582 kW, 0.1981 % volume, 24.5720 ppm, and 710.9470 ppm, respectively. When the results of the optimization process were compared to the experimental results, the deviations were found to be within the acceptable range of errors which establish the robustness of RSM model.

Long-term C and N sequestration under no-till is governed by biomass production of cover crops rather than differences in grass vs. legume biomass quality

Agricultural activities through conventional and intensive practices contribute to climate change by increasing emission of reactive carbon (C) and nitrogen (N) from soils to the atmosphere. Minimum soil disturbance, appropriate residue management and cover cropping as conservation practices are perceived as key strategies to limit GHGs emissions by increasing soil C and N sequestration as soil organic matter (SOM), thus promoting soil aggregation and enhancing soil fertility. Yet, the actual contribution of conservation practices to C and N sequestration, as well as mechanisms behind chemical and biochemical stabilization of SOM in the long-term are still controversial. In the present 9-year field study on a wheat-maize-soybean rotation we investigated the effect of no-till (NT) coupled with grass vs. legume cover crop (i.e., rye [Secale cereale L., NT-R] or hairy vetch [Vicia villosa Roth, NT-V]) on main crop yields, C and N input by cover and main crops, soil aggregation and C and N sequestration rates, in comparison with conventional tillage (CT). We hypothesized that NT-R may lead to higher biomass input, C sequestration and comparable yield to CT, while NT-V may increase N input, N sequestration and lead to comparable yield to CT. We found that yield of winter wheat, maize, and soybean were never reduced under both NT treatments, neither during the transition phase, nor afterwards. Rye and hairy vetch provided the same amount of biomass and C input, although vetch doubled N input compared with rye. Moreover NT-V increased cumulative biomass and C input from main crop residues compared with NT-R. Both NT-R and NT-V promoted C (+0.4 Mg ha−1 y−1 and +0.6 Mg ha−1 y−1, respectively) and N (+88 kg ha−1 y−1 and +145 kg ha−1 y−1, respectively) soil sequestration, mainly due to the increase of macroaggregate-associated C and N, thus corroborating a major role of NT for macroaggregates formation and SOM stabilization within macroaggregates. Since no difference was found between cover crops in terms of biomass input, and C and N sequestration potential, we concluded that cover crop biomass production (rather than biomass quality) and retention onto the soil as residue were the main drivers of soil C and N sequestration. Therefore, both rye and hairy vetch may be combined with NT and promise significant potential as effective C farming practices.

Gasoline compression ignition (GCI) combustion in a light-duty engine using double injection strategy

Controlling the oxides of nitrogen (NOx) and particulate matter (PM) emissions is one of the vital goals of compression ignition (CI) engines. Implementing stringent emissions regulations has motivated researchers to adopt various strategies for controlling emissions. Gasoline compression ignition (GCI) has emerged as a prime technology to control emissions and increase engine efficiency, while using low-octane gasoline as fuel in CI engines. Preheated air, hot exhaust gas recirculation (EGR), and negative valve overlap, are required to manage the combustion instabilities in the GCI engines. However these techniques have not been used in this study in order to reduce system complexity. Low octane test fuel was prepared (G80) by blending 80 % v/v gasoline and 20 % v/v diesel. This study involved experiments to evaluate the effects of main injection timing, split injection quantities (10–30 %), and engine load (brake mean effective pressure (BMEP): 3–5 bar) on a two-cylinder GCI engine’s performance, combustion, cyclic variability, emissions, and particulates. Conventional diesel combustion (CDC) mode experiments were performed using diesel. The results indicated a 5 % higher brake thermal efficiency (BTE) and comparable exhaust gas temperature (EGT) for the GCI mode compared to the baseline CDC mode. GCI combustion with low split ratio showed higher in-cylinder pressure than CDC mode. Baseline CDC mode showed < 3 % coefficient of variation of indicated mean effective pressure and peak pressure, whereas these parameters varied from 1 % to 9 % in the GCI mode. GCI mode engine exhibited ∼ 60 and 50 % lower NOx and PM emissions than baseline diesel mode engine. The double injection strategy improved GCI engine's performance and emission characteristics.

Ammonium-free and grain-protection deliming technology with the combination of aromatic sulfonic acid and sodium dihydrogen phosphate in leather manufacture

Ammonia-nitrogen, a grave environmental concern, is a typical pollutant in deliming process due to the inclusion of ammonium salts as deliming agents in leather manufacture. In order to reduce the emission of ammonia-nitrogen and improve the biological treatment of mixed tannery wastewater, an ammonium-free deliming method was designed and optimized based on the synergistic effects of aromatic sulfonic acids and sodium dihydrogen phosphate. The results indicated that, the penetrating and buffering performance of the mixtures of p-Hydroxybenzene sulfonic acid (pHBSA) and sodium dihydrogen phosphate (SDHP) at weight ratio of 2:1 was good enough to fulfill the requirement of deliming. The organoleptic and mechanical properties of the crust leather produced by pHBSA-SDHP mixtures deliming were similar with the conventional ammonium sulfate deliming, and the grain pattern was found to be protected against the damage caused by enzymes during bating. The concentrations of ammonia-nitrogen and total nitrogen in pHBSA-SDHP deliming effluent were dramatically cut down by 99% and 94%. It is anticipated that the mixed tannery wastewater could be disposed of more easily by means of adjusting the total organic ratios of C:N:P to their natural ratio by introducing an additional carbon and phosphorus source to the tannery wastewater. This investigation provides an improved method of leather making with significant reduction of ammonia nitrogen emission in deliming operation and fulfills the integral requirements of the modern sustainable leather industry.

Assessing the Impact of Agricultural Practices on Nitrogen Emission and Environmental Sustainability

Nitrogen emissions from agricultural activities have garnered increasing attention due to their implications for environmental sustainability. Field studies conducted throughout a month is needed to improve flux estimates for the greenhouse gas nitrous oxide (N2O). In this study, we reported N2O emissions measured using gas chromatograph equipped with an electron capture detector. The soil at the experimental site was loamy. N2O emissions were significantly higher from the root systems of nodulating soybeans compared to non-nodulating soybeans during the late growth period. To mitigate nitrogen emissions in soybean cultivation, optimize fertilizer application, promote biological nitrogen fixation through inoculation and legume cover cropping, implement crop rotation, use cover crops, reduce nitrogen loss through erosion control, manage irrigation efficiently, employ precision agriculture, educate on nutrient stewardship, utilize biofertilizers, conduct environmental monitoring, invest in legume breeding, and enact government regulations and incentives for sustainable nitrogen management practices. Therefore, this study significantly advances our knowledge of sustainable soybean cultivation and the pivotal role and means in mitigating environmental challenges linked to nitrogen emissions.

TECHNOLOGICAL MANAGEMENT OF THE REDUCTION OF ECOLOGICALLY HARMFUL EMISSIONS OF ANIMAL HUSBANDRY INTO THE ENVIRONMENT (review)

The purpose. To study the influence of various factors on the emissions of nitrogen and phosphorus compounds into the environment for the optimization of technological management and prospective planning of research in pig farming, as well as increasing the efficiency of the use of nutrients by pigs in their group housing. Methods. The material for the research was literature from the library of the Institute of Pig Breeding and AIP of the National Academy of Agrarian Sciences of Ukraine and scientific works of scientists from Google Academy, Pub med, base-search.net, core.ac.uk, ouci.dntb.gov.ua. The following research methods were used in the research process: general scientific (typology, classification, analysis and synthesis, abstract-logical) and interdisciplinary (structural-system approach), historical (problematic-chronological, descriptive, source and historical analysis and synthesis), with their help systematized scientific data on the technological management of reducing ecologically harmful emissions of animal husbandry into the environment. The results. Management strategies used in science and practice to improve the efficiency of nitrogen and phosphorus use in pig production are discussed, namely: genetic selection, castration, slaughter weight, precision feeding, and manure management systems. Since the diet significantly affects the possible losses of nitrogen and phosphorus, it must be taken into account when evaluating management strategies. The amount of nitrogen released depends on the amount of absorbed nitrogen, the amount of absorbed nitrogen, the balance of amino acids in the diet and the animal's need for nitrogen and amino acids. For group-housed animals, polyphasic feeding systems should be used, as daily polyphasic feeding tailored to the individual animal's amino acid and other nutrient needs is likely to be most effective. Specific amino acid intake should be balanced using the ideal protein concept. With better knowledge of the needs of individual animals and the commercial availability of certain amino acids, the total level of crude protein in the diet can be reduced within certain limits. However, further research is needed on the minimum level of crude protein that provides maximum performance. The correct use of feed additives and enzyme preparations in rations contributes to the reduction of nitrogen and phosphorus emissions. By combining optimal feeding and management, nitrogen assimilation efficiencies approaching 60% can be achieved in the near future. Prospective manure collection and processing systems contribute to an even greater reduction of environmental emissions. Conclusions. The use of effective management systems and precise feeding in pig farming contributes to the increase of assimilation of nitrogen and phosphorus from feed, respectively, to the reduction of nitrogen and phosphorus emissions to the environment. Key words: emissions, pigs, nitrogen, phosphorus, excretion, amino acids, genetic selection, castration, slaughter weight, animal age.

Combined effects of hydrogen and TiO2 nanoparticle additive on terebinth oil biodiesel operated diesel engine

Efforts to reduce the dependency on fossil-based fuels have intensely been researched by scientists recently. Therefore, in internal combustion engines, the usability of various alternative fuels is still being evaluated. The present study experimentally focused on the illumination of the combined impacts of nanoparticle additives and hydrogen fuel on the performance and emission characteristics of a compression ignition engine. For this purpose, diesel fuel and combinations of diesel fuel, terebinth oil biodiesel, titanium dioxides nanoparticle, and hydrogen were utilized. Reduced engine performance caused by biodiesel was compensated with the use of nanoparticles. Further improvement was also observed with hydrogen addition. Emission results showed that carbon monoxide (CO) emission values can be reduced with biodiesel, nanoparticle additive, and hydrogen since they all have positive effects to enhance combustion quality and avoid incomplete combustion. On the other hand, oxides of nitrogen (NOx) emission was increased due to a rise in cylinder temperature with the use of biodiesel, nanoparticle, and hydrogen.

Analysis of the Emissions and Performance of a Diesel Engine Using Pumpkin Seed Oil Methyl Ester with Different Injection Pressures

Biodiesel fuel is a potential alternative energy source for diesel engines due to its physiochemical characteristics relatively similar to those of traditional diesel fuel. In this study, the performance, emission, and combustion features of a mono cylinder DI diesel engine are assessed using 20% Pumpkin seed methyl ester (PSOME20) and considering varying injection pressures (200, 220, 240, and 260 bar). The considered Pumpkin seed oil is converted into pumpkin biodiesel by transesterification and then used as fuel. The findings demonstrate that the Brake Thermal Efficiency (BTE) of PSOME20 can be raised by 1.68%, and the carbon monoxide (CO), hydrocarbon (HC), and smoke emanations can be lowered, while oxides of nitrogen (NOx) emissions are increased at an injection pressure (IP) of 240 bar compared to the standard IP of 200 bar. The cylinder pressure and the Heat Release Rate (HRR) become higher at 240 bar, whereas the ignition delay is shortened with respect to PSOME20 at a normal IP of 200 bar.

Effects of a low-protein diet supplemented with essential amino acids on egg production performance and environmental gas emissions from layer-manure composting in laying hens in the later laying period.

We fed 330-545 day-old laying hens (later laying period) a low-protein diet supplemented with essential amino acids (LPS) and composted their manure. We then investigated the laying performance of the hens, the nitrogen balance and emission of nitrous oxide (N2 O), methane (CH4 ), and ammonia (NH3 ) from the composting, and several characteristics of the finished compost. There were no significant differences in the egg-laying rate, egg mass, egg weight, proximate compositions in egg yolk and egg white, or feed intake between the laying hens fed a Control diet (Cont) and those fed the LPS diet. However, the LPS-fed hens had lower excreta levels and nitrogen excretion. In addition, the environmental gas emissions per layer from composting of the manure from the LPS-fed laying hens were decreased by 9.7% for N2 O, 40.9% for CH4 , and 24.8% for NH3 compared to the Cont-fed laying hens. The concentrations of total nitrogen in the finished compost were similar between the LPS-fed and Cont-fed laying hens. In a vegetable-growth test, the weights of komatsuna plants grown with compost from LPS-fed and Cont-fed hens were also not significantly different. Feeding an LPS diet to 330-545 day-old laying hens was suggested to reduce environmental gas emissions from manure composting without affecting the egg production performance.

Life Cycle Environmental Impact Assessment of Aquaculture Products in the Gaza Strip, Palestine

This study used the life cycle assessment (LCA) approach to evaluate the environmental impacts resulting from aquaculture ponds and associated activities. The assessment focused on eutrophication, acidification, global warming, energy use, and local nutrient emissions. Two farms, Fish Fresh and Al-Bahar, were analyzed to determine the contribution of different components in fish farming systems to various impact categories. Data on fish feed, onsite electricity, feed milling electricity, fuel intensity, water input, and fish production were meticulously collected through a comprehensive questionnaire and insightful interviews conducted over a one-year period in 2020. Furthermore, valuable information was diligently gathered regarding the nitrogen and phosphorus emissions in aquaculture ponds, with a focus on feed inputs. Environmental indicators were evaluated using a functional unit of 1 ton and 1 kg of live fish weight. Results reveled that global warming impacts varied between the two farms, with feed production being the primary contributor, accounting for 74.73% and 76.30% of total emissions, respectively. Acidifying emissions were mainly generated through fish production, accounting for 74.8% and 76.3% of the total for Fish Fresh and Al-Bahar farms, respectively. Eutrophication was primarily driven by fish production, while feed production and transportation operations also made noticeable contributions. The average emissions per kilogram of fresh fish were higher for the Fish Fresh farm compared to Al-Bahar in terms of global warming, acidification, and eutrophication. Energy consumption and water dependence also varied between the farms. These findings emphasize the importance of considering environmental impacts throughout the life cycle of fish farming in the Gaza Strip.

NOx reduction system selection and energy efficiency impact evaluation for ships sailing in restricted areas

The worldwide shipping provides 90 percent of the goods carriage and in the last 20 years their absolute volume is constantly increasing. However, carriers need to maintain service levels and reduce exploitation costs, and at the same time must ensure higher sustainability in all operations. The growth in number of ships in service inevitably leads to much more harmful emissions released by vessels in to the atmosphere. In the same time, more stringent environmental requirements and laws continue to regulate the maritime transport sector. Progress was made by International Maritime Organization (IMO) towards the ambition on reduction of greenhouse gas (GHG) emissions from ships. That is why IMO based International Convention for the Prevention of Pollution from Ships (MARPOL Convention) and its regulations continuously sets higher thresholds for environment protection expressed by Nitrous Oxides (NOx), Sulphur Oxides (SOx) and Carbone Dioxides (CO2) limitations. The new higher ecological requirements put on the table new technical and economic challenges for the shipowners and ship designers.In the current paper Selective Catalytic Reduction (SCR) and Exhaust Gas Bypass (EGR) NOx emissions reduction systems and their affect on the fuel consumption are under consideration. The application of each system depends on the ship’s type, installed propulsion system and its main engines and operational modes.The numerical study is carried based on 31800 DWT vessel for bulk loads, operating in restricted areas of the Great Lakes of North America. In the course of the research the fulfilment of the following objectives are being leaned: the ship must be capable for operation in Nitrogen Emission Control Areas (NECA’s), as well as its Energy Efficiency Design Index (EEDI) must be in compliance with Required Energy Efficiency Design Index (REEDI) Phase 3 coming in force in 2025.

Emission analysis in an EGR‐equipped DI diesel engine fueled by butanol‐diesel blends

AbstractIn this present work, the impacts of exhaust gas recirculation (EGR) on exhaust emissions of a diesel engine powered with the blending of butanol with mineral diesel under different engine loads were studied. Experimental tests were performed using butanol‐diesel blends on a single cylinder, constant speed, direct injection (DI) unmodified diesel engine at different proportions by vol%. A higher alcohol—Butanol of 10%, 20%, and 30% blended with mineral diesel fuel. Three different EGR rates of 10 to 30% were employed to reduce the oxides of nitrogen (NOx) emissions that prevailed at higher engine loads. Experimental results revealed that by increasing the EGR rates reduces nitrogen oxide emissions by up to 32% at higher loads. Whereas smoke opacity barely raised to an EGR rate of 20%. There was a rise in hydrocarbon (HC) emissions and a slight surge in carbon monoxide (CO) emissions found with butanol‐diesel blends rather than mineral diesel. NOx emissions were decreased by 29% for 70% Diesel + 30% Butanol (Bu30) blend with EGR 30% than mineral diesel fuel. There is an increase in smoke opacity with engine load because of the burning of a higher amount of energy to generate higher brake power. Smoke opacity is decreased to 68.9% using Bu30 than conventional diesel. Overall, it was found that blends of 30% of butanol and 70% of diesel can be employed in existing unmodified diesel engines.

A Study on the Carbon Neutral Effect and Improvement of River Water Quality through Non-point Source Pollution Control in Farmland

In Korea, the carbon emission from the agricultural, livestock, and fishery sectors were 24.7 million tCO&lt;sub&gt;2&lt;/sub&gt;-eq in 2018. Following the 2050 carbon neutral declaration, the total carbon emissions from these sectors are expected to decrease to 15.4 million tCO&lt;sub&gt;2&lt;/sub&gt;-eq by 2050, a reduction of 37.7%. Therefore, efforts are being made to reduce the use of chemical fertilizers, soil nitrogen emissions, and greenhouse gases in the agricultural sector. In this study, we analyzed the effects of irradiation charges on greenhouse gas reduction and water quality improvement after rice cultivation without the addition of any fertilizer. The greenhouse gas emission for fertilizer during irradiation cultivation was estimated to be 237 kgCO&lt;sub&gt;2&lt;/sub&gt;-eq/1,000m&lt;sup&gt;2&lt;/sup&gt;, 4 kgCO&lt;sub&gt;2&lt;/sub&gt;-eq/1,000m&lt;sup&gt;2&lt;/sup&gt; less than that by using a crop protection agent (241 kgCO&lt;sub&gt;2&lt;/sub&gt;-eq/1,000m&lt;sup&gt;2&lt;/sup&gt;). The measurement was based on the amount of nitrogen, phosphorus, and potassium (62.90, 22.83, and 19.31 kg, respectively) per 1,000 m&lt;sup&gt;2&lt;/sup&gt; barley cultivation. In addition, a reduction in fertilizer use was estimated to reduce eutrophication by approximately 25.47 kgPO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt;-eq. Thus, the eutrophication of rivers from farmland, a nonpoint pollution source, is predicted to reduce by expanding irradiation cultivation.

Potential to mitigate nitrogen emissions from paddy runoff: A microbiological perspective

Ditches and ponds are the basic units of agroecosystems that serve irrigation and drainage and also perform the natural ecological function of reducing nitrogen (N) emissions. To better enhance the design and advance management strategies in the paddy field ecosystem to minimize N emission, the N cycling microorganism in the paddy field ecosystem including interconnected fields with rice-wheat rotation, ditches, and ponds in central China was investigated by metagenomic techniques. Our results showed that ditches and ponds may be N removal hotspots by microorganisms in the rice and wheat seasons respectively. Given seasonal variation, the abundance of N-related microorganisms was high during the rice season. However, the Shannon and Simpson indices were lower and the microbial co-occurrence network was destabilized, which could make microbes in the rice season fragile and sensitive. Phytoplankton as key environmental factors affecting the N cycling microbial could promote more stable microbial communities through maintaining a good mutualistic symbiosis. While high algae concentration significantly promotes the abundance of norB than nosZ (P < 0.05), which may result in more N2O production. To trade off N removal and N2O emission, the algae concentration needs to be controlled. Our findings provide a systematic profile of N-related microorganisms in the paddy field ecosystem, and it would benefit in developing effective strategies for limiting N pollution in agriculture.

Effect of pilot injection strategy on the methanol-mineral diesel fueled reactivity controlled compression ignition combustion engine

Amongst all low-temperature combustion (LTC) strategies, reactivity-controlled compression ignition (RCCI) combustion garners more debate from researchers because of its excellent combustion and performance characteristics and lower emissions over a wide operating range. In this experimental investigation, the consequences of the start of diesel injection (SoIdiesel) timing using different pilot injection techniques, such as single and double pilot injection (SPI and DPI, respectively), have been investigated. Tests were performed at a fixed engine speed and load (1500 rpm and 3 bar BMEP, respectively) using different premixed ratios (rp: 0, 0.25, 0.50, and 0.75) of methanol on an energy basis. Experimental results indicated that the start of combustion (SoC) and combustion phasing (CP) advanced with advancing SoIdiesel. However, too advanced and retarded SoIdiesel timings resulted in combustion noise and misfire. The use of pilot injection was found suitable for the RCCI mode, especially at lower rp. However, SPI and DPI strategies didn’t show significant variations in the combustion characteristics. Exhaust gas temperature (EGT) showed a random trend with SoIdiesel timing, and it decreased with the increasing number of pilot injections. RCCI mode produced higher hydrocarbon (HC) and carbon monoxide (CO) and lower oxides of nitrogen (NOx) emissions. All these gaseous emissions decreased with advancing the SoIdiesel. Particulate matter (PM) analysis showed that the RCCI mode emitted relatively lower PM than the baseline CI mode, further reducing with increased methanol fuelling. PM emissions also decreased by retarding SoIdiesel, in which reduction in smaller particles was dominant. The analysis of critical parameters such as brake thermal efficiency (BTE), HC, NOx, and PM emissions suggested that the optimum rp of methanol and suitable injection strategy can significantly improve the combustion, performance, and emissions characteristics of the RCCI mode.

Sustainable farming strategies for mixed crop-livestock farms in Luxembourg simulated with a hybrid agent-based and life-cycle assessment model

Agent-based models (ABMs) are particularly suitable to simulate human-natural systems since they allow modelers to consider the behavioral aspects of individuals. Life Cycle Assessment (LCA) has also been widely used in research, industry, and policy to assess systems' environmental sustainability. In this paper, we introduce a coupled ABM-LCA model to simulate mixed crop-livestock farming activities in the Grand Duchy of Luxembourg. The simulator considers a wide range of aspects related to typical farming business activities and allows the calculation of the environmental and economic impacts of the decisions taken by agents as well. The paper simulates different scenarios. Scenario A is the baseline scenario. Scenario B considers reducing the stocking rate from 1.6 to 1.3 livestock units per ha (LSU/ha). Scenario C aims to reduce the soybean ratio in animals’ feed rations to the minimum possible level that is feasible for each farm. Scenario D simulates an increase in soybean autonomy: the farmer chooses to adopt local soybean (instead of imported one) into the crop rotation if its green consciousness exceeds a pre-fixed threshold. As expected, in scenario B, all impact categories show improvement with respect to the baseline scenario, the highest ones being an almost 25% reduction in freshwater eutrophication, 21% in climate change - human health, and 19% in freshwater ecotoxicity. For natural land transformation, the most significant improvements are obtained in scenarios C (11% reduction) and D (13% reduction). On the other hand, in scenario C, the change in feed composition, combined with an expected decrease in stocking rates, also has a positive effect (about 16% reduction compared to the baseline) on agricultural land occupation, due to the utilization of pasture and locally produced crops. An analysis of the systemic uncertainty calculated at the endpoint indicators level showed low coefficients of variation (CV) for all the scenarios, with scenario A always having the lowest values of CV in every impact category, scenario C having the highest CV in the ecosystem quality and the human health categories and scenario B having the highest CV in the resources category. The consideration of subsidy schemes in the Grand Duchy of Luxembourg allows the modelers to better interpret the resulting revenue and cost structures of different scenarios. The results show that the farm profitability stays on the same level when the stocking rate is reduced, and the subsidy granted for reducing nitrogen emissions is in place at the same time. Moreover, the soybean autarky in Luxembourg can be increased to 17% if the farmers are willing to incorporate soybean into their rotation scheme, thus reducing the impacts due to the transportation and production of soybean in South American countries.

Emission dynamics of greenhouse gases regulated by fluctuation of water level in river-connected wetland

The application of reservoirs in the upper reaches of rivers will change the hydrological rhythm of river-connected wetlands in the lower reaches, causing changes in the distribution of wetland vegetation. The differences of carbon and nitrogen sequestration and emission potential in different vegetations may lead to the dynamics of greenhouse gas emissions from wetlands during hydrological periods. For a wetland connected to the Yangzi River, China, the dynamic changes of vegetation and water areas were identified by remote sensing, and the water level, the emission fluxes of greenhouse gases and the functional bacteria of carbon and nitrogen in soil were measured in-situ. Compared with drought period, the area of phragmites zone in flooding period increased by 28.2%, while the areas of carex and phalaris zones decreased by 42.9%. The carbon and nitrogen accumulation in the soil of phragmites zone is the highest, while the cumulative amount of phalaris is the lowest. The emission fluxes of CH4 and N2O in mud/water and various vegetations were positively correlated with water level and reached the maximum during flooding period. Although the global warming potential of mud/water was highest than that of vegetations, carex zone had the highest warming potential among vegetation zones. CH4 contributes 8–37 times as much as N2O to global warming potential in the wetland. The increase of flooding time promoted the emissions of CH4 and N2O in the wetland. The anaerobic condition caused by flooding stimulated the activities of denitrifying and methanogenic bacteria, thus increasing the emission of greenhouse gases. The sequestrations and emissions of carbon and nitrogen regulated by a reservoir in the upstream suggest that the operation of water conservancies should be considered to alleviate the greenhouse gas emission from river-connected wetland.