Ammonia Loss Research Articles

Improved tools for estimation of ammonia emission from field-applied animal slurry: Refinement of the ALFAM2 model and database

Ammonia volatilization from animal slurry applied to agricultural fields reduces nitrogen use efficiency in agriculture and pollutes the environment. This work presents new versions of a model and database focused on this route of N loss. The public ALFAM2 database (https://github.com/AU-BCE-EE/ALFAM2-data) was expanded with ammonia emission and ancillary measurements for >700 additional field plots. The ALFAM2 model (https://github.com/AU-BCE-EE/ALFAM2, https://zenodo.org/records/13312251) was extended with the addition of an ammonia sink for more plausible predictions over extended durations and to better reflect the expected reduction in emission rate several days after slurry application. A new parameter set was developed for the model taking into account the newly available measurement data. Model efficiency improved to 0.67 for the parameter estimation subset (0.52 for cross-validation) and mean absolute error was around 10% of applied total ammoniacal nitrogen. As in earlier versions, predicted emission is sensitive to application method, slurry dry matter and pH, air temperature, and wind speed. A collection of parameter sets for estimating uncertainty in average predictions was developed using a bootstrap approach. Predicted uncertainty is not trivial, and is high for some variable combinations, highlighting the challenge of making predictions based on available measurement data. Still, this work has resulted in more accurate, comprehensive, transparent, and flexible tools for emission inventory and related work on ammonia loss from field-applied slurry.

The Effect of the Use of a Novel Urease Inhibitor Coated Urea on the Greenhouse Gas Emissions and Ammonia Volatilization Losses from a Maize Field

Nitrogen fertilizers are essential for enhancing agricultural productivity but are also major contributors to greenhouse gas (GHG) emissions and ammonia volatilization, which affect environmental sustainability. This study evaluated the effect of cashew nut shell liquid (CNSL)-coated urea on GHG emissions and ammonia losses from maize fields in the Indo-Gangetic Plains, known for excessive nitrogen fertilizer usage. A randomized block design was employed with four treatments: control (no nitrogen), prilled urea, neem-coated urea (NCU), and CNSL-coated urea (CCU). Gas samples were collected using the closed chamber method, and emissions of CO₂ and N₂O were analyzed via gas chromatography. Ammonia volatilization was measured using the forced air draft method. Results showed that the CCU treatment significantly reduced ammonia volatilization compared to prilled urea (15.84% reduction), with reductions of 9% to those observed with NCU. Moreover, CCU-treated plots exhibited reduced cumulative GHG and lower global warming potential (GWP) without compromising maize yields. Cumulative GHG emissions varied among the treatments in the order urea> CCU> NCU> Control. CCU treated plots exhibited a net GWP decrease of 8.59% compared to urea and an increase of 4.13% compared to NCU. These findings suggest that CNSL-coated urea can serve as an eco-friendly alternative to conventional urea, potentially mitigating environmental impacts associated with nitrogen fertilization. Further studies are recommended to assess the long-term efficacy of CNSL in various soil types and climatic conditions.

Reduction in Ammonia Volatilization from Pig Slurry Using Acidic Mechanisms

ABSTRACT Pig slurry can be used as an alternative source for nutrients, particularly nitrogen (N), for plants. However, after applying the pig slurry to the soil, gaseous loss of N this nutrient may occur, mainly in the form of ammonia. Hence this study aimed to evaluate the loss of N by volatilization after the application of pig slurry with an acidified pH. Ammonia volatilization was evaluated using pig slurry, with its pH modified to 5.0 using four acids (sulfuric acid, citric acid, ascorbic acid, and acetic acid). Additionally, pig slurry with natural pH and a control were also used. The work was conducted in a greenhouse, and collectors were used to capture the volatilized ammonia in a static free semi-open chamber. The application of pig slurry with natural pH (7.19) resulted in 61% loss of ammonia, whereas acidification with ascorbic acid (pH 5.0) caused a loss of only 26%. The application of pig slurry with pH above 7.0 caused N loss, indicating that using acids to maintain a pH of 5.0–6.0 could be an alternative to reduce N loss by ammonia volatilization.

Water absorption from air and ammonia loss from urea fertilizers applied to grassland in southeastern United States

AbstractInformation on water absorption from the air by urea fertilizers and on NH3 loss when applied to grasslands is limited. Urea application to grassland is typically broadcast (Bcast), whereas urea‐ammonium nitrate (UAN) is applied either Bcast or in bands (dribble). This work was conducted to (1) evaluate water absorption from the air by Bcast granular urea, Bcast UAN, and dribble UAN under laboratory conditions, and (2) compare NH3 losses from Bcast urea, Bcast UAN, and dribble UAN when applied to a grassland. Six field studies were conducted from 2017 to 2019. In the laboratory, Bcast UAN exposed to 100% relative humidity absorbed water from air at a faster rate than dribble UAN and Bcast urea. In the field, all three fertilizers lost similar amounts of NH3 when applied to relatively wet soil (> −0.1 MPa). In contrast, when the fertilizers were applied to dry soil (≤ −1.2 MPa), Bcast UAN lost the most NH3 (17.3% and 19.8%) likely because of its capacity to absorb water from the air. Also, at −1.2 MPa, dribble UAN lost more NH3 than Bcast urea (15.3 vs. 10.7%, p < 0.05), probably because the low osmotic potential of UAN (−55 MPa) allowed it to absorb water from the soil at a faster rate than urea could absorb water from the air. In contrast, when the soil water potential was −5.7 MPa, dribble UAN lost less NH3 than Bcast urea (4.4 vs. 17.3%, p < 0.05), likely because the low soil water potential reduced its water absorption.

Decomposition and Growth Pathways for Ammonium Nitrate Clusters and Nanoparticles.

Understanding the formation and decomposition mechanisms of aerosolized ammonium nitrate species will lead to improvements in modeling the thermodynamics and kinetics of aerosol haze formation. Studying the sputtered mass spectra of cation and anion ammonium nitrate clusters can provide insights as to which growth and evaporation pathways are favored in the earliest stages of nucleation and thereby guide the development and use of accurate models for intermolecular forces for these systems. Simulated annealing Monte Carlo optimization followed by density functional theory optimizations can be used reliably to predict minimum-energy structures and interaction energies for the cation and anion clusters observed in mass spectra as well as for neutral nanoparticles. A combination of translational and rotational mag-walking and sawtooth simulated annealing methods was used to find optimum structures of the various heterogeneous clusters identifiable in the mass spectra. Following these optimizations with ωB97X-D3 density functional theory calculations made it possible to rationalize the pattern of peaks in the mass spectra through computation of the binding energies of clusters involved in various growth and dissociation pathways. Testing these calculations against CCSD(T) and MP2 predictions of the structures and binding energies for small clusters demonstrates the accuracy of the chosen model chemistry. For the first time, the peaks corresponding with all detectable species in both the positive and negative ion mass spectra of ammonium nitrate are identified with their corresponding structures. Thermodynamic control of particle growth and decomposition of ions due to loss of ammonia or nitric acid molecules is indicated. Structures and interaction energies for larger (NH4NO3)n nanoparticles are also presented, including the prediction of new particle morphologies with trigonal pyramidal character.

Impact of a forage legume or nitrogen fertilizer application on ammonia volatilization and nitrous oxide emissions in Brachiaria pastures

ABSTRACT The largest proportion of greenhouse gas (GHG) emissions in the Agriculture sector of the Brazilian national GHG inventory is derived from the large (>200 million head) herd of cattle. The greatest contribution to these emissions comes from the enteric methane from cattle, but the direct and indirect emissions of nitrous oxide (N 2 O) from cattle excreta and N fertilizer are responsible for approximately 9 % of all national anthropogenic GHG emissions. Ammonia (NH 3 ) can be volatilized from N fertilizer and cattle excreta and deposited in sites remote from the source, constituting an indirect source of N 2 O. This study aimed to determine whether direct N 2 O emissions and NH 3 volatilization from N-fertilized pastures were greater than those derived from a mixed grass-legume pasture without N fertilizer addition. Emissions of N 2 O and NH 3 from excreta and N fertilizer from a Palisade grass (Urochloa brizantha cv. Marandu) monoculture fertilized with 2 × 60 kg N ha -1 yr -1 urea were compared to those from a mixed Palisade grass-forage peanut (Arachis pintoi) pasture. Dung and urine were collected from these cattle, and NH 3 losses and N 2 O emissions from the excreta and from N fertilizer were monitored using static chamber techniques. Volatilization of NH 3 and N 2 O emissions were found to be greater from urine than from dung. Ammonia losses from excreta and urea fertilizer were low, not exceeding 6.8, 1.1, and 4.7 % of the N applied as urine, dung, and fertilizer, respectively. The N 2 O emissions showed a tendency to be greater for the urine from the N-fertilized compared to the mixed grass-legume pasture, and the N 2 O emissions from the urine of the N-fertilized pasture ranged from 0.08 to 0.94 % of applied urine N. The N 2 O emission from the N fertilizer was at maximum 0.46 % of the applied N. The direct N 2 O emissions and the loss of NH 3 by volatilization (indirect N 2 O emission) from the excreta of cattle grazing the mixed grass-legume pasture were similar to, or lower than, the grazed grass monoculture fertilized with 120 kg N ha -1 yr -1 . As the mixed pasture received no N fertilizer and hence no GHG emission from its manufacture or application, introducing forage peanut to the Urochloa brizantha pastures shows potential to be responsible for lower GHG emissions than the N fertilized grass pasture.

Dispersion of anhydrous ammonia inside a confined space onboard a hypothetical ammonia-powered vessel

Abstract In order to ensure the responsible use of anhydrous ammonia as clean marine fuel, safety aspects in respect of its post-release consequence cannot be understated. This contribution is aimed to address the gaps of understanding associated to events of ammonia loss of containment (LoC) in enclosed spaces onboard ammonia-fuelled vessels. A forced ventilated fuel preparation room (FPR) onboard a container vessel is chosen as a study case with minor and major release scenarios, which is based on the orifice size. The dispersion analysis was performed using three-dimensional computational fluid dynamics. The analysis revealed that toxicity associated to the rapid and persistent ammonia vapor cloud buildup is by far the most significant hazard in the space. In the major release scenario, gradual evaporation of rainout pool increases the vapor cloud persistence even far beyond the leak isolation time. The results and finding above underlines the importance of concerted effort in mitigating not only the ammonia vapor cloud, but also the accumulated ammonia liquid pool.

Machine learning-assisted optimization of food-grade spirulina cultivation in seawater-based media: From laboratory to large-scale production

The shortage of food and freshwater sources threatens human health and environmental sustainability. Spirulina grown in seawater-based media as a healthy food is promising and environmentally friendly. This study used three machine learning techniques to identify important cultivation parameters and their hidden interrelationships and optimize the biomass yield of Spirulina grown in seawater-based media. Through optimization of hyperparameters and features, eXtreme Gradient Boosting, along with the recursive feature elimination (RFE) model demonstrated optimal performance and identified 28 important features. Among them, illumination intensity and initial pH value were critical determinants of biomass, which impacted other features. Specifically, high initial pH values (>9.0) mainly increased biomass but also increased nutrient sedimentation and ammonia (NH3) losses. Both batch and continuous additions could decrease nutrient losses by increasing their availability in the seawater-based media. When illumination intensity exceeded 200 μmol photons/m2/s, it amplified the growth of Spirulina by mitigating the light attenuation caused by a high initial inoculum level and counteracted the negative effect of low temperature (<25 °C). In large-scale cultivation, production efficiency would be reduced if illumination was not maintained at a high level. High salinity and sodium bicarbonate (NaHCO3) addition promoted carbohydrate accumulation, but suitable dilution could keep the required protein content in Spirulina with relatively low media and production costs. These findings reveal the interactive influence of cultivation parameters on biomass yield and help us determine the optimal cultivation conditions for large-scale cultivation of Spirulina-based seawater system based on a developed graphical user interface website.

Effects of biochar and wood vinegar co-application on composting ammonia and nitrous oxide losses and fertility

Composting faces challenges with nitrogen (N) losses through ammonia (NH3) and nitrous oxide (N2O) emissions. In this study, wood vinegar (WV) and biochar (BC) were applied individually or combined into wheat straw and chicken manure composting. Results showed that BC and WV reduced NH3 volatilizations by 22–23 % individually, but their combined application achieved a 59 % reduction. However, this combination increased N2O emissions by 174 %. The BC + WV treatment improved compost quality, evidenced by increased total N content by 22 % and enhanced the biological index, promoting additional dissolved organic matter production. Overall, BC and WV applications improved compost quality, reduced gaseous N losses, and supported the re-utilization of agricultural residues. The combined use of BC and WV significantly enhances compost quality and reduces NH3 emissions, offering a promising solution for sustainable agricultural residue management.

Identification and genomic analysis of a thermophilic bacterial strain that reduces ammonia loss from composting.

Ammonia loss is the most severe during the high-temperature stage (>50°C) of aerobic composting. Regulating ammonia volatilization during this period via thermophilic microbes can significantly improve the nitrogen content of compost and reduce air pollution due to ammonia loss. In this study, an ammonia-assimilating bacterial strain named LL-8 was screened out as having the strongest ammonia nitrogen conversion rate (32.7%) at high temperatures (50°C); it is able to significantly reduce 42.9% ammonia volatile loss in chicken manure composting when applied at a high-temperature stage. Phylogenetic analysis revealed that LL-8 was highly similar (>98%) with Priestia aryabhattai B8W22T and identified as Priestia aryabhatta. Genomic analyses indicated that the complete genome of LL-8 comprised 5,060,316 base pairs with a GC content of 32.7% and encoded 5,346 genes. Genes, such as gudB, rocG, glnA, gltA, and gltB, that enable bacteria to assimilate ammonium nitrogen were annotated in the LL-8 genome based on the comparison to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The results implied that the application of thermophilic ammonia-assimilating strain P. aryabhatta LL-8 would be a promising solution to reduce ammonia loss and mitigate air pollution of aerobic composting.IMPORTANCEAerobic composting is one of the essential ways to recycle organic waste, but its ammonia volatilization is severe and results in significant nitrogen loss, especially during the high-temperature period, which is also harmful to the environment. The application of thermophilic bacteria that can use ammonia as a nitrogen source at high temperatures is helpful to reduce the ammonia volatilization loss of composting. In this study, we screened and identified a bacteria strain called LL-8 with high temperature (50°C) resistance and strong ammonia-assimilating ability. It also revealed significant effects on decreasing ammonia volatile loss in composting. The whole-genome analysis revealed that LL-8 could utilize ammonium nitrogen by assimilation to decrease ammonia volatilization. Our work provides a theoretical basis for the application of this functional bacteria in aerobic composting to control nitrogen loss from ammonia volatilization.

[N x H3x+1 +][BH4 −] (x = 1−5): role of polynuclear superalkalis in chemical hydrogen storage

Ammonium borohydride, [NH4 +][BH4 −], despite its high gravimetric hydrogen density, can not be used for hydrogen storage due to its instability against dehydrogenation. In this paper, we have replaced NH4 + with polynuclear N x H3x+1 + cations and studied the resulting [N x H3x+1 +][BH4 −] complexes for x = 2–5 using density functional theory. N x H3x+1 + are superalkali cations, whose vertical electron affinity is lower than the ionisation energy of alkali cations. Their binding energy, dehydrogenation energy and enthalpy, being higher than that of [NH4 +][BH4 −], increase with an increase in x. Thus, these complexes are more stable than [NH4 +][BH4 −], which comes at the cost of slightly decreased gravimetric hydrogen density. The enhanced stability of [N x H3x+1 +][BH4 −] complexes is a consequence of the lower vertical electron affinity, i.e. the superalkali properties of N x H3x+1 + cations. Further, their stability against the loss of ammonia suggests a possible route of synthesis of these complexes. Thus, the superalkalis play an important role in the design of more stable and novel borohydrides for hydrogen storage.

Kinetics of ammonium volatilization in the form of ammonia in soils through a textural gradient

Objective: To estimate the ammonia volatilization rate, using a texture gradient with increasing doses of ammonium in alkaline soils. Design/Methodology/Approach: The experiment took place in the Análisis Químico de Suelos lab of the Soil Department of the Universidad Autónoma Chapingo. The incubations consisted of 25 g of soil from the former Texcoco lake, with 12.5% clay. The soil was air-dried and sieved with a no. 10 mesh. The soil was mixed with three different concentrations (17.5%, 22.5%, and 32.5%) of bentonite, in order to increase clay content. The mixtures were placed in plastic containers with airtight seals. Twelve-point five mL of an ammonium sulfate solution (with 150, 300, 450, 600, and 750 mg of nitrogen kg soil-1) was added. The ammonia was recovered in a container with a boric acid solution. Volumetry was used to quantify ammonium. A completely randomized design with two factors (clay content and ammonium dose) was used. Data were analyzed with a regression analysis, analysis of variance, and Tukey Multiple Comparison Test, using the SAS OnDemand for Academics software. Results: The ammonia volatilization has a linear trend, with the concentration of the applied nitrogen. The volatilization rate ranged from 0.02 to 0.03 mg of ammonium per milligram of the nitrogen applied per kg soil-1. Significant statistical differences were recorded between the effect of the N dose and the clay content on the ammonia volatilization rate. Study Limitations/Implications: Clay content in the soil and ammonia volatilization rate can be used as an indicator to estimate ammonia losses and the ammonia adsorption capacity of the soil. Findings/Conclusions: Ammonia volatilization is independent from clay content and takes place immediately after its application. It has a linear trend regarding the ammonia dose applied. Ammonia volatilization rate decreases (asymptotic trend) as the clay content increases in the soil.

Humic Acids Combined with Dairy Slurry as Fertilizer Can Increase Alfalfa Yield and Reduce Nitrogen Losses

Dairy slurry could be a significant source of nitrogen (N) for plants, but mismanagement can lead to atmospheric ammonia losses or nitrate leaching into groundwater. To make the use of dairy slurry efficient and reasonable, the loss of N pollution to the environment should be reduced. We used repacked lysimeters to comprehensively determine ammonia emission and N leaching losses in an alfalfa–soil system. The application of dairy slurry had no significant effect on alfalfa yield at the same rate of N application in comparison to chemical fertilizer, and adding humic acids significantly increased yield by about 12%. However, the application of dairy slurry increased the ammonia emission rate significantly, leading to an increase in the cumulative amount of ammonia emission, while the addition of humic acids reduced the ammonia emissions by 11%. Chemical fertilizer and dairy slurry application significantly increased nitrate leaching compared to the control treatment, while the addition of humic acids can significantly reduce ammonium N leaching. Dairy slurry was proven to be as effective as chemical N fertilizer in achieving the optimum biomass, and adding humic acids can significantly reduce N loss to the atmosphere and groundwater. This study showed the possibility of replacing chemical fertilizer with dairy slurry in alfalfa production and the advantages of humic acids’ addition to alfalfa to maintain production yield and improve environmental friendliness.

The soil sample conservation method and its potential impact on ammonium, nitrate and total mineral nitrogen measurements

Scientific literature for mineral soil nitrogen content (ammonium and nitrate) measurements usually differs regarding the chosen soil sample conservation method (fresh, frozen or air-dry) before soil extraction and analysis. In addition, most of the commonly used methodologies focus on the definition of the analysis processes, regardless of the previous sample conservation methodology. With the aim to fill this gap, we performed an analysis of the conservation method effect on the nitrate, and ammonium content in frozen or air-dried samples, comparing the results with direct fresh extraction. Moreover, the effects of additional soil parameters, such as soil texture, organic matter content or mineral nitrogen content range were also studied. The results showed that both, frozen and air drying soil samples, were capable of reliably preserving the N content of soil samples in most cases. However, some ammonium losses may occur in frozen samples when a high N content (>30 mg kg−1) is present. It was also observed that air-dried soil samples can reduce the soil nitrate and increase ammonium content in samples with a high N content. It was also observed that significant amounts of organic matter in soil can alter the mineral N measured depending on the conservation method chosen. On the other hand, the soil texture presented small effects on the mineral N measurements. In any case, a broader range of soils conditions (including i.e. pH or different natural organic matter content) should be further tested to confirm our findings.

Comparative analysis of multi-effect evaporators in an ammonium acetate concentration process for L-methionine production

The process of treating an acetic acid aqueous solution generated during L-methionine production with ammonia and recovering a highly concentrated ammonium acetate aqueous solution using a multi-effect evaporator process was studied. The electrolyte non-random two-liquid model was applied to calculate the activity in the electrolyte solution, and the Hayden-O’Connell model was used to consider the dimerization reaction of acetic acid in the vapor phase. The dissociation equilibrium constant of acetic acid was modeled based on experimental values, and all other thermodynamic property models and parameters were used as implemented in the Aspen Plus software. Economic evaluation was carried out with various sensitivity tests, considering the loss of acetic acid and ammonia, as well as the steam cost. Evaporator operation was found to be more economical when the molar ratio of acetic acid to ammonia was equal, feed concentration was high, feed flow rate was low, and evaporator temperature was low. These results were confirmed in actual plant operations, with significant correlations between the feed flow rate and evaporator temperature. Our findings have significant implications for the development of sustainable and economical L-methionine production methods that enable the recycling of ammonium acetate.

Increasing urine nitrification performance with sequential membrane aerated biofilm reactors

This study aimed to investigate whether separating organics depletion from nitrification increases the overall performance of urine nitrification. Separate organics depletion was facilitated with membrane aerated biofilm reactors (MABRs). The high pH and ammonia concentration in stored urine inhibited nitrification in the first stage and therewith allowed the separation of organics depletion from nitrification. An organics removal of 70 % was achieved at organic loading rates in the influent of 3.7 gCOD d−1 m−2. Organics depletion in a continuous flow stirred tank reactor (CSTR) for organics depletion led to ammonia stripping through diffused aeration of up to 13 %. Using an MABR, diffusion into the lumen amounted for 4 % ammonia loss only. In the MABR, headspace volume and therefore ammonia loss through the headspace was negligible. By aerating the downstream MABR for nitrification with the off-gas of the MABR for organics depletion, 96 % of the ammonia stripped in the first stage could be recovered in the second stage, so that the overall ammonia loss was negligibly low. Nitrification of the organics-depleted urine was studied in MABRs, CSTRs, and sequencing batch reactors in fed batch mode (FBRs), the latter two operated with suspended biomass. The experiments demonstrated that upstream organics depletion can double the nitrification rate. In a laboratory-scale MABR, nitrification rates were recorded of up to 830 mgNL−1 d−1 (3.1 gN m−2 d−1) with ambient air and over 1500 mgNL−1 d−1 (6.7 gN m−2 d−1) with oxygen-enriched air. Experiments with a laboratory-scale MABR showed that increasing operational parameters such as pH, recirculation flow, scouring frequency, and oxygen content increased the nitrification rate. The nitrification in the MABR was robust even at high pH setpoints of 6.9 and was robust against process failures arising from operational mistakes. The hydraulic retention time (HRT) required for nitrification was only 1 to 2 days. With the preceding organics depletion, the HRT for our system requires 2 to 3 days in total, whereas a combined activated sludge system requires 4 to 8 days. The N2O concentration in the off-gas increases with increasing nitrification rates; however, the N2O emission factor was 2.8 % on average and independent of nitrification rates. These results indicate that the MABR technology has a high potential for efficient and robust production of ammonium nitrate from source-separated urine.

15N mass balance technique for measuring ammonia losses from soil surface‐applied slurries containing various additives

AbstractBackgroundAnthropogenic ammonia emissions, primarily derived from agriculture, lead to air pollution, soil acidification, and surface water eutrophication, all of which adversely affect human health and ecosystems. Slurry treatment technologies in the form of additives represent an underutilized means of reducing gaseous emissions. Information regarding the potential of additives to reduce ammonia in soil surface‐applied slurries is scarce.AimThis study aims to develop a 15N mass balance technique to quantitatively measure ammonia losses from different slurries containing multiple additives that are applied to outdoor soil‐filled containers.MethodsThe experiments were performed under free‐air conditions. Isotopically labeled slurries from biogas, cattle, and pigs containing 18 additives were surface‐applied to soil‐filled containers and exposed for 72 or 48 h. The additives included inorganic and organic adsorbents, five amounts of sulfuric acids, molasses ± effective microorganisms, and water dilution. After termination of the ammonia loss period, a suite of soil preparation steps for the quantitative recovery of the labeled ammonium remaining in the soil was developed, and subsequently the loss of NH4‐N was determined.ResultsIn the control treatments, ammonia losses from biogas, cattle slurries, and pig slurries averaged 54.4%, 33.9%, and 11.0%, respectively. The adsorbents did not decrease or only slightly decreased ammonia emissions. Ammonia abatement by sulfuric acid was nearly complete at pH values of 5.9 and 5.8 for the biogas and pig slurry, respectively, and about 80% at pH 5.2 for the cattle slurry. In comparison, more moderately decreased pH values with sulfuric acid showed a similar reduction as molasses and a 1:1 dilution for the three slurries. Adding microorganisms to the molasses did not further decrease ammonia losses.ConclusionThe newly developed 15N mass balance technique, which allows a precise estimate of ammonia losses, can serve as a reference method to assess ammonia losses from field‐applied slurries containing various additives and as a standard comparison technique for other ammonia measurement techniques.

Implementation of various injection rate shapes in an ammonia/diesel dual-fuel engine with special emphasis on combustion and emissions characteristics

As the problem of global warming continues to intensify, carbon-free fuel ammonia is crucial for internal combustion engines, and a potential ammonia combustion route is dual-fuel mode. The impact of various injection rate shapes (trapezoid, wedge, slope, triangle, and rectangle) on engine combustion and emissions performance with 0 %, 20 %, and 40 % ammonia energy fractions were estimated. Under the identical ratio of the ammonia-doped schemes, the fuel injection gross mass and fuel injection duration are the same. The results indicate that the triangle injection rate shape can make the mixture of diesel and ammonia gas more uniform, leading to combustion in the combustion chamber closer to homogeneous combustion. When the injection shape is the triangle, the indicated mean effective pressure in the cylinder is the highest at 10.29 bar, which is 4.04 % higher than that of the pure diesel original injection shape. The triangle injection shape makes the ammonia-diesel dual fuel burn more concentrated, resulting in lower unburned ammonia loss and higher thermal efficiency. Under the 40 % ammonia energy fraction and triangle injection shape, the highest thermal efficiency reaches 40.57 %, 1.58 % higher than the pure diesel original injection shape. Additionally, it significantly reduces unburned ammonia emissions. The injection rate shapes have a minor impact on CO2 emissions. The rapid increase in-cylinder average temperature can substantially reduce N2O emissions, thereby lowering total greenhouse gas emissions. Among them, the total greenhouse gas emissions of 40 % ammonia energy fraction and triangle injection shape are the lowest, at 81619 ppm, which is 11.3 % lower than that of pure diesel original injection shape. On the contrary, it will increase NOx emissions. Conversely, the slopes exhibit the lowest NOx emissions at 220.8 ppm, representing an 88 % reduction compared to the pure diesel original injection shape.

Enriched rice husk biochar superior to commercial biochar in ameliorating ammonia loss from urea fertilizer and improving plant uptake

Adding value to agricultural leftovers and turning them into biochar is a viable way to replenish soil nutrients and boost crop productivity. To further validate the efficacy of enriched rice husk biochar, an incubation study and a pot experiment were conducted: (1) to describe the effect of enriched rice husk biochar addition on soil total N, soil exchangeable NH4+ and available NO3− and (2) to describe the effect of enriched rice husk biochar on improving N, P, K, Ca, and Mg uptake, use efficiency, and dry matter production of rice plants. The amount of NH3 loss that was considerably reduced by rice husk biochar at 5 and 10 t ha−1 was 34 % lower than the control. The availability of soil total N, exchangeable NH4+, available NO3−, available P, and exchangeable cations was greatly enhanced by the addition of rice husk biochar. Due to the effective nutrient uptake that occurs with an increase in soil nutrient level, the physical growth of the rice plant (height, tiller number, greenness, and panicle number) increeased significantly in treatments supplemented with 5 t ha−1 rice husk biochar. When rice plants were treated with 5 t ha−1 rice husk biochar, their absorption of N, P, and K increased by >80 %, respectively. The production of dry matter in rice plants increased as a result of the increased N intake. The application of 5 t ha−1 of rice husk biochar enhanced the soil nutrients by reducing NH3 loss and augmenting soil nutrients for efficient plant absorption, as demonstrated by the favourable enhancement of soil macro- and micronutrients and biomass of rice plants.

Tandem mass spectrometry of homologous 3-hydroxyfurazan and nitrile amino acids: Analysis of cooperative interactions and fragmentation processes.

The assignment of structure by tandem mass spectrometry (MS/MS) relies on the interpretation of the fragmentation behavior of gas-phase ions. Mass spectra were acquired for a series of heterocyclic mimetics of acidic amino acids and a related series of nitrile amino acids. All amino acids were readily protonated or deprotonated by electrospray ionization (ESI), and distinctive fragmentation processes were observed when the ions were subjected to collision-induced dissociation (CID). The deprotonated heterocycles showed bond cleavages of the 3-hydroxyfurazan ring with formation of oxoisocyanate and the complementary deprotonated nitrile amino acid. Further fragmentation of the deprotonated nitrile amino acids was greatly dependent on the length of the alkyl nitrile side chain. Competing losses of CO2 versus HCN occurred from α-cyanoglycinate (shortest chain), whereas water was lost from 2-amino-5-cyanopentanoate (longest chain). Interestingly, loss of acrylonitrile by a McLafferty-type fragmentation process was detected for 2-amino-4-cyanobutanoate, and several competing processes were observed for β-cyanoalanate. In one process, cyanide ion was formed either by consecutive losses of ammonia, carbon dioxide, and acetylene or by a one-step decarboxylative elimination. In another, complementary ions were obtained from β-cyanoalanate by loss of acetonitrile or HN=CHCO2H. Fragmentation of the protonated 3-hydroxyfurazan and nitrile amino acids resulted in the cumulative loss (H2O + CO), a loss that is commonly observed for protonated aliphatic α-amino acids. Overall, the distinct fragmentation behavior of the multifunctional 3-hydroxyfurazan amino acids correlated with the charged site, whereas fragmentations of the deprotonated nitrile amino acids showed cooperative interactions between the nitrile and the carboxylate groups.