Challenges of accounting nitrous oxide emissions from agricultural crop residues.

Crop residues are important inputs of carbon (C) and nitrogen (N) to soils and thus directly and indirectly affect nitrous oxide (N2 O) emissions. As the current inventory methodology considers N inputs by crop residues as the sole determining factor for N2 O emissions, it fails to consider other underlying factors and processes. There is compelling evidence that emissions vary greatly between residues with different biochemical and physical characteristics, with the concentrations of mineralizable N and decomposable C in the residue biomass both enhancing the soil N2 O production potential. High concentrations of these components are associated with immature residues (e.g., cover crops, grass, legumes, and vegetables) as opposed to mature residues (e.g., straw). A more accurate estimation of the short-term (months) effects of the crop residues on N2 O could involve distinguishing mature and immature crop residues with distinctly different emission factors. The medium-term (years) and long-term (decades) effects relate to the effects of residue management on soil N fertility and soil physical and chemical properties, considering that these are affected by local climatic and soil conditions as well as land use and management. More targeted mitigation efforts for N2 O emissions, after addition of crop residues to the soil, are urgently needed and require an improved methodology for emission accounting. This work needs to be underpinned by research to (1) develop and validate N2 O emission factors for mature and immature crop residues, (2) assess emissions from belowground residues of terminated crops, (3) improve activity data on management of different residue types, in particular immature residues, and (4) evaluate long-term effects of residue addition on N2 O emissions.

Revisiting sampling duration to estimate N2O emission factors for manure application and cattle excreta deposition for the UK and Ireland.

According to the available guidelines, good practices for calculating nitrous oxide (N2O) emission factors (EFs) for livestock excreta and manure application include that sampling duration should be of at least one year after the nitrogen (N) application or deposition. However, the available experimental data suggest that in many cases most emissions are concentrated in the first months following N application. Therefore resources could be better deployed by measuring more intensively during a shorter period. This study aimed to assess the contribution of the N2O flux in the period directly after N application to the annual net emission. We used a database of 100 year-long plot experiments from different excreted-N sources (dung, urine, farmyard manure and slurry) used to derive EFs for the UK and Ireland. We explored different shorter potential measurement periods that could be used as proxies for cumulative annual emissions. The analysis showed that the majority of emissions occur in the first months after application, especially in experiments that i) had urine as the N source, ii) had spring N application, iii) were conducted on fine-textured soils, or iv) showed high annual emissions magnitude. Experiments that showed a smaller percentage of emissions in the first months also had a low magnitude of annual net emissions (below 370 gN2O-N ha-1 year-1), so the impact of measuring during a shorter period would not greatly influence the calculated EF. Accurate EF estimations were obtained by measuring for at least 60 days for urine (underestimation: 7.1%), 120 days for dung and slurry (4.7 and 5.1%) and 180 days for FYM (1.4%). At least in temperate climates, these results are promising in terms of being able to estimate annual N2O fluxes accurately by collecting data for less than 12 months, with significant resource-saving when conducting experiments towards developing country-specific EFs.

Does liming grasslands increase biomass productivity without causing detrimental impacts on net greenhouse gas emissions?

Soil acidification has negative impacts on grass biomass production and the potential of grasslands to mitigate greenhouse gas (GHG) emissions. Through a global review of research on liming of grasslands, the objective of this paper was to assess the impacts of liming on soil pH, grass biomass production and total net GHG exchange (nitrous oxide (N2O), methane (CH4) and net carbon dioxide (CO2)). We collected 57 studies carried out at 88 sites and covering different countries and climatic zones. All of the studies examined showed that liming either reduced or had no effects on the emissions of two potent greenhouse gases (N2O and CH4). Though liming of grasslands can increase net CO2 emissions, the impact on total net GHG emission is minimal due to the higher global warming potential, over a 100-year period, of N2O and CH4 compared to that of CO2. Liming grassland delivers many potential advantages, which justify its wider adoption. It significantly ameliorates soil acidity, increases grass productivity, reduces fertiliser requirement and increases species richness. To realise the maximum benefit of liming grassland, we suggest that acidic soils should be moderately limed within the context of specific climates, soils and management.

Predicting field N2O emissions from crop residues based on their biochemical composition: A meta-analytical approach.

Crop residue incorporation is a common practice to increase or restore organic matter stocks in agricultural soils. However, this practice often increases emissions of the powerful greenhouse gas nitrous oxide (N2O). Previous meta-analyses have linked various biochemical properties of crop residues to N2O emissions, but the relationships between these properties have been overlooked, hampering our ability to predict N2O emissions from specific residues. Here we combine comprehensive databases for N2O emissions from crop residues and crop residue biochemical characteristics with a random-meta-forest approach, to develop a predictive framework of crop residue effects on N2O emissions. On average, crop residue incorporation increased soil N2O emissions by 43% compared to residue removal, however crop residues led to both increases and reductions in N2O emissions. Crop residue effects on N2O emissions were best predicted by easily degradable fractions (i.e. water soluble carbon, soluble Van Soest fraction (NDS)), structural fractions and N returned with crop residues. The relationship between these biochemical properties and N2O emissions differed widely in terms of form and direction. However, due to the strong correlations among these properties, we were able to develop a simplified classification for crop residues based on the stage of physiological maturity of the plant at which the residue was generated. This maturity criteria provided the most robust and yet simple approach to categorize crop residues according to their potential to regulate N2O emissions. Immature residues (high water soluble carbon, soluble NDS and total N concentration, low relative cellulose, hemicellulose, lignin fractions, and low C:N ratio) strongly stimulated N2O emissions, whereas mature residues with opposite characteristics had marginal effects on N2O. The most important crop types belonging to the immature residue group - cover crops, grasslands and vegetables - are important for the delivery of multiple ecosystem services. Thus, these residues should be managed properly to avoid their potentially high N2O emissions.

Ammonia and nitrous oxide emission factors for excreta deposited by livestock and land-applied manure.

Manure application to land and deposition of urine and dung by grazing animals are major sources of ammonia (NH3 ) and nitrous oxide (N2 O) emissions. Using data on NH3 and N2 O emissions following land-applied manures and excreta deposited during grazing, emission factors (EFs) disaggregated by climate zone were developed, and the effects of mitigation strategies were evaluated. The NH3 data represent emissions from cattle and swine manures in temperate wet climates, and the N2 O data include cattle, sheep, and swine manure emissions in temperate wet/dry and tropical wet/dry climates. The NH3 EFs for broadcast cattle solid manure and slurry were 0.03 and 0.24 kg NH3 -N kg-1 total N (TN), respectively, whereas the NH3 EF of broadcast swine slurry was 0.29. Emissions from both cattle and swine slurry were reduced between 46 and 62% with low-emissions application methods. Land application of cattle and swine manure in wet climates had EFs of 0.005 and 0.011 kg N2 O-N kg-1 TN, respectively, whereas in dry climates the EF for cattle manure was 0.0031. The N2 O EFs for cattle urine and dung in wet climates were 0.0095 and 0.002 kg N2 O-N kg-1 TN, respectively, which were three times greater than for dry climates. The N2 O EFs for sheep urine and dung in wet climates were 0.0043 and 0.0005, respectively. The use of nitrification inhibitors reduced emissions in swine manure, cattle urine/dung, and sheep urine by 45-63%. These enhanced EFs can improve national inventories; however, more data from poorly represented regions (e.g., Asia, Africa, South America) are needed.

DATAMAN: A global database of nitrous oxide and ammonia emission factors for excreta deposited by livestock and land-applied manure.

Nitrous oxide (N2 O), ammonia (NH3 ), and methane (CH4 ) emissions from the manure management chain of livestock production systems are important contributors to greenhouse gases (GHGs) and NH3 emitted by human activities. Several studies have evaluated manure-related emissions and associated key variables at regional, national, or continental scales. However, there have been few studies focusing on the drivers of these emissions using a global dataset. An international project was created (DATAMAN) to develop a global database on GHG and NH3 emissions from the manure management chain (housing, storage, and field) to identify key variables influencing emissions and ultimately to refine emission factors (EFs) for future national GHG inventories and NH3 emission reporting. This paper describes the "field" database that focuses on N2 O and NH3 EFs from land-applied manure and excreta deposited by grazing livestock. We collated relevant information (EFs, manure characteristics, soil properties, and climatic conditions) from published peer-reviewed research, conference papers, and existing databases. The database, containing 5,632 observations compiled from 184 studies, was relatively evenly split between N2 O and NH3 (56 and 44% of the EF values, respectively). The N2 O data were derived from studies conducted in 21 countries on five continents, with New Zealand, the United Kingdom, Kenya, and Brazil representing 86% of the data. The NH3 data originated from studies conducted in 17 countries on four continents, with the United Kingdom, Denmark, Canada, and The Netherlands representing 79% of the data. Wet temperate climates represented 90% of the total database. The DATAMAN field database is available at http://www.dataman.co.nz.

Electron beam-induced deposition of platinum from Pt(CO)2Cl2 and Pt(CO)2Br2.

Two platinum precursors, Pt(CO)2Cl2 and Pt(CO)2Br2, were designed for focused electron beam-induced deposition (FEBID) with the aim of producing platinum deposits of higher purity than those deposited from commercially available precursors. In this work, we present the first deposition experiments in a scanning electron microscope (SEM), wherein series of pillars were successfully grown from both precursors. The growth of the pillars was studied as a function of the electron dose and compared to deposits grown from the commercially available precursor MeCpPtMe3. The composition of the deposits was determined using energy-dispersive X-ray spectroscopy (EDX) and compared to the composition of deposits from MeCpPtMe3, as well as deposits made in an ultrahigh-vacuum (UHV) environment. A slight increase in metal content and a higher growth rate are achieved in the SEM for deposits from Pt(CO)2Cl2 compared to MeCpPtMe3. However, deposits made from Pt(CO)2Br2 show slightly less metal content and a lower growth rate compared to MeCpPtMe3. With both Pt(CO)2Cl2 and Pt(CO)2Br2, a marked difference in composition was found between deposits made in the SEM and deposits made in UHV. In addition to Pt, the UHV deposits contained halogen species and little or no carbon, while the SEM deposits contained only small amounts of halogen species but high carbon content. Results from this study highlight the effect that deposition conditions can have on the composition of deposits created by FEBID.

Predicting nitrous oxide emissions after the application of solid manure to grassland in the United Kingdom.

Nitrous oxide (N2 O) emission from agricultural soils represents a significant source of greenhouse gas to the atmosphere. We evaluated the suitability of a modified Soil and Water Assessment Tool (SWAT) model to estimate the N2 O flux from the application of solid manure at two grassland sites (North Wyke [NW] and Pwllpeiran [PW]) in the United Kingdom. The simulated N2 O emissions were validated against field observations measured in 2011 and 2012 for model calibration and validation, respectively. The SWAT model predicts water-filled pore space (WFPS) very well with Nash-Sutcliffe efficiency (NSE), R2 , RMSE, and percentage bias (PBIAS) values of 0.67, .72, 0.06, and 3.64, respectively, during the calibration period for NW site, whereas it gives 0.68, .69, 0.07, and 3.04, respectively during the validation period. At PW, the model predicted the NSE, R2 , RMSE, and PBIAS of 0.55, .69, 0.04, and -4.5, respectively, during calibration and 0.63, .71, 0.05, and -2.6, respectively, during the validation period. Compared with WFPS, the model resulted in a slightly lower fit for N2 O emissions for NW (NSE = 0.47, R2  = .63 during calibration, and NSE = 0.55, R2  = .58 during validation) and for PW (NSE = 0.54, R2  = .71 for calibration, and NSE = 0.47, R2  = .69 for validation). Results revealed that the SWAT model performed reasonably well in representing the dynamics of N2 O emissions after solid manure application to grassland.

Global Research Alliance N2 O chamber methodology guidelines: Design considerations.

Terrestrial ecosystems, both natural ecosystems and agroecosystems, generate greenhouse gases (GHGs). The chamber method is the most common method to quantify GHG fluxes from soil-plant systems and to better understand factors affecting their generation and mitigation. The objective of this study was to review and synthesize literature on chamber designs (non-flow-through, non-steady-state chamber) and associated factors that affect GHG nitrous oxide (N2 O) flux measurement when using chamber methods. Chamber design requires consideration of many facets that include materials, insulation, sealing, venting, depth of placement, and the need to maintain plant growth and activity. Final designs should be tailored, and bench tested, in order to meet the nuances of the experimental objectives and the ecosystem under study while reducing potential artifacts. Good insulation, to prevent temperature fluctuations and pressure changes, and a high-quality seal between base and chamber are essential. Elimination of pressure differentials between headspace and atmosphere through venting should be performed, and designs now exist to eliminate Venturi effects of earlier tube-type vent designs. The use of fans within the chamber headspace increases measurement precision but may alter the flux. To establish best practice recommendations when using fans, further data are required, particularly in systems containing tall plants, to systematically evaluate the effects that fan speed, position, and mixing rate have on soil gas flux.

Global Research Alliance N2 O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability.

Adequately estimating soil nitrous oxide (N2 O) emissions using static chambers is challenging due to the high spatial variability and episodic nature of these fluxes. We discuss how to design experiments using static chambers to better account for this variability and reduce the uncertainty of N2 O emission estimates. This paper is part of a series, each discussing different facets of N2 O chamber methodology. Aspects of experimental design and sampling affected by spatial variability include site selection and chamber layout, size, and areal coverage. Where used, treatment application adds a further level of spatial variability. Time of day, frequency, and duration of sampling (both individual chamber closure and overall experiment duration) affect the temporal variability captured. We also present best practice recommendations for chamber installation and sampling protocols to reduce further uncertainty. To obtain the best N2 O emission estimates, resources should be allocated to minimize the overall uncertainty in line with experiment objectives. Sometimes this will mean prioritizing individual flux measurements and increasing their accuracy and precision by, for example, collecting four or more headspace samples during each chamber closure. However, where N2 O fluxes are exceptionally spatially variable (e.g., in heterogeneous agricultural landscapes, such as uneven and woody grazed pastures), using available resources to deploy more chambers with fewer headspace samples per chamber may be beneficial. Similarly, for particularly episodic N2 O fluxes, generated for example by irrigation or freeze-thaw cycles, increasing chamber sampling frequency will improve the accuracy and reduce the uncertainty of temporally interpolated N2 O fluxes.

Identifying and Rationalizing the Differing Surface Reactions of Low-Energy Electrons and Ions with an Organometallic Precursor.

Surface reactions of electrons and ions with physisorbed organometallic precursors are fundamental processes in focused electron and ion beam-induced deposition (FEBID and FIBID, respectively) of metal-containing nanostructures. Markedly different surface reactions occur upon exposure of nanometer-scale films of (η5-Cp)Fe(CO)2Re(CO)5 to low-energy electrons (500 eV) compared to argon ions (860 eV). Electron-induced surface reactions are initiated by electronic excitation and fragmentation of (η5-Cp)Fe(CO)2Re(CO)5, causing half of the CO ligands to desorb. Residual CO ligands decompose under further electron irradiation. In contrast, Ar+-induced surface reactions proceed by an ion-molecule momentum/energy transfer process, causing the desorption of all CO ligands without significant ion-induced precursor desorption. This initial decomposition step is followed by ion-induced sputtering of the deposited atoms. The fundamental insights derived from this study can be used not only to rationalize the composition of deposits made by FEBID and FIBID but also to inform the choice of a charged particle deposition strategy and the design of new precursors for these emerging nanofabrication tools.

Dissociation of the FEBID precursor cis-Pt(CO)2Cl2 driven by low-energy electrons.

In this study, we present experimental and theoretical results on dissociative electron attachment and dissociative ionisation for the potential FEBID precursor cis-Pt(CO)2Cl2. UHV surface studies have shown that high purity platinum deposits can be obtained from cis-Pt(CO)2Cl2. The efficiency and energetics of ligand removal through these processes are discussed and experimental appearance energies are compared to calculated thermochemical thresholds. The present results demonstrate the potential effectiveness of electron-induced reactions in the deposition of this FEBID precursor, and these are discussed in conjunction with surface science studies on this precursor and the design of new FEBID precursors.

Design, Synthesis, and Evaluation of CF3AuCNR Precursors for Focused Electron Beam-Induced Deposition of Gold.

The Au(I) complexes CF3AuCNMe (1a) and CF3AuCN tBu (1b) were investigated as Au(I) precursors for focused electron beam-induced deposition (FEBID) of metallic gold. Both 1a and 1b are sufficiently volatile for sublimation at 125 ± 1 mTorr in the temperature range of roughly 40-50 °C. Electron impact mass spectra of 1a-b show gold-containing ions resulting from fragmenting the CF3 group and the CNR ligand, whereas in negative chemical ionization of 1a-b, the major fragment results from dealkylation of the CNR ligand. Steady-state depositions from 1a in an Auger spectrometer produce deposits with a similar gold content to the commercial precursor Me2Au(acac) (3) deposited under the same conditions, while the gold content from 1b is less. These results enable us to suggest the likely fate of the CF3 and CNR ligands during FEBID.

Gross N transformation rates and related N2O emissions in Chinese and UK agricultural soils.

The properties of agricultural soils in various regions of the world are variable and can have a significant but poorly understood impact on soil nitrogen (N) transformations and nitrous oxide (N2O) emissions. For this reason, we undertook a study of gross N transformations and related N2O emissions in contrasting agricultural soils from China and the UK. Seven Chinese and three UK agricultural soils were collected for study using a 15N tracing approach. The soil pH ranged from 5.4 to 8.7, with three acidic soils collected from Jinjing, Lishu and Boghall; one neutral soil collected from Changshu, and the other six alkaline soils collected from Quzhou, Zhangye, Changwu, Jinzhong, Boxworth and Stetchworth. Our results showed that the main N transformation processes were oxidation of ammonium (NH4+) to nitrate (NO3-) (ONH4), and mineralization of organic N to NH4+. The gross autotrophic nitrification rates calculated in the three acidic soils were between 0.25 and 4.15 mg N kg-1 d-1, which were significantly lower (p < 0.05) than those in the remaining neutral and alkaline soils ranging from 6.94 to 14.43 mg N kg-1 d-1. Generally, soil pH was positively correlated (p < 0.001) with gross autotrophic nitrification rate and cumulative N2O emissions, indicating that soil pH was an important factor regulating autotrophic nitrification and N2O emissions. There was also a significant positive correlation between the gross autotrophic nitrification rate and cumulative N2O emissions, highlighting the importance of this process for producing N2O emissions in these agricultural soils under aerobic conditions. Gross NH4+ immobilization rates were very low in most soils except for the Jinjing soil with the lowest pH. In conclusion, the gross autotrophic nitrification rates and related N2O emissions were controlled by soil pH irrespectively of the soil's origin in these agricultural soils.

Modeling nitrous oxide emissions from digestate and slurry applied to three agricultural soils in the United Kingdom: Fluxes and emission factors.

Organic fertilizers, such as digestates and manure, are increasingly applied in agricultural systems because of the benefits they provide in terms of plant nutrients and soil quality. However, there are few investigations of N2O emissions following digestate application to agricultural soils using process-based models. In this study, we modified the UK-DNDC model to include digestate applications to soils by adding digestate properties to the model and considering the effect of organic fertilizer pH. Using the modified model, N2O emissions were simulated from two organic fertilizers (digested food waste and livestock slurry) applied to three farms in the United Kingdom: one growing winter wheat at Wensum (WE) and two grasslands at Pwllpeiran (PW) and North Wyke (NW). The annual cumulative gross (i.e. not excluding control emission) N2O emissions were calculated using MATLAB trapezoidal numerical integration. The relative errors of the modeled annual cumulative emissions to the measured emissions ranged from -5.4% to 48%. Two-factor models, including linear, exponential and hyperbola responses, correlating total N loading and soil clay content to calculations of N2O emissions and N2O emission factors (EFs) were developed for calculations of emission fluxes and EFs. The squares of the correlation coefficients of the measured and two-factor linear modeled emissions were 0.998 and 0.999 for digestate and slurry, respectively, and the corresponding squares of correlation coefficients of the EFs were 0.998 and 0.938. The two-factor linear model also predicted that the EFs increased linearly with decreasing clay content and the maximum EFs for digestate and slurry were 0.95 and 0.76% of total N applied, respectively. This demonstrates that the modified UK_DNDC is a good tool to simulate N2O emission from digestate and slurry and to calculate UK EFs using TIER 3 methodology..

Modeling nitrous oxide emissions from three United Kingdom farms following application of farmyard manure and green compost.

Organic fertilizers, such as manure and compost, are promising additions for synthetic fertilizers in order to increase soil fertility and crop yields. However, the organic fertilizers applied to soils may increase nitrous oxide (N2O, a greenhouse gas) emissions due to their lower C/N ratios, and therefore potentially contribute to global warming. Very few studies have used process-based models to assess the environmental advantages and drawbacks of compost soil amendments compared to other field treatments. In this study, the UK-DNDC model was modified for simulation of nitrous oxide (N2O) fluxes emitted from the soils treated with green compost and farmyard manure at three UK farms (WE, PW and NW): one winter wheat and two grasslands. The results show that the annual overall N2O emissions were 1.45 kg N ha-1 y-1 for WE treated with farmyard manure, 0.71 for WE with green compost, 1.09910 for PW treated with farmyard manure, 0.94 for PW treated with green compost, 1.19 for NW treated with farmyard manure, and 1.18 for NW treated with green compost. A two dimensional linear model was developed to correlate nitrogen loading and soil pH for calculations of emissions and emission factors (EFs). The linear model could fit the emissions obtained from the UK-DNDC model well. The squares of correlation coefficients of the emissions between two models are 0.993 and 0.985 for farmyard manure and green compost, respectively. Analysis of correlation coefficients between N2O emissions and air temperature, precipitation as well as the time period between fertilizer application and sample measurement (PFS) for the three sites treated with farmyard manure and compost indicated that N2O emissions were mainly related to PFS. The modified DNDC model provides an approach to estimating N2O emissions from compost amended soils.

Electron induced surface reactions of (η5-C5H5)Fe(CO)2Mn(CO)5, a potential heterobimetallic precursor for focused electron beam induced deposition (FEBID).

Electron-induced surface reactions of (η5-C5H5)Fe(CO)2Mn(CO)5 were explored in situ under ultra-high vacuum conditions using X-ray photoelectron spectroscopy and mass spectrometry. The initial step involves electron-stimulated decomposition of adsorbed (η5-C5H5)Fe(CO)2Mn(CO)5 molecules, accompanied by the desorption of an average of five CO ligands. A comparison with recent gas phase studies suggests that this precursor decomposition step occurs by a dissociative ionization (DI) process. Further electron irradiation decomposes the residual CO groups and (η5-C5H5, Cp) ligand, in the absence of any ligand desorption. The decomposition of CO ligands leads to Mn oxidation, while electron stimulated Cp decomposition causes all of the associated carbon atoms to be retained in the deposit. The lack of any Fe oxidation is ascribed to either the presence of a protective carbonaceous matrix around the Fe atoms created by the decomposition of the Cp ligand, or to desorption of both CO ligands bound to Fe in the initial decomposition step. The selective oxidation of Mn in the absence of any Fe oxidation suggests that the fate of metal atoms in mixed-metal precursors for focused electron beam induced deposition (FEBID) will be sensitive to the nature and number of ligands in the immediate coordination sphere. In related studies, the composition of deposits created from (η5-C5H5)Fe(CO)2Mn(CO)5 under steady state deposition conditions, representative of those used to create nanostructures in electron microscopes, were measured and found to be qualitatively consistent with predictions from the UHV surface science studies.

Low energy electron-induced decomposition of (η5-Cp)Fe(CO)2Mn(CO)5, a potential bimetallic precursor for focused electron beam induced deposition of alloy structures.

The production of alloyed nanostructures presents a unique problem in focused electron beam induced deposition (FEBID). Deposition of such structures has historically involved the mixing of two or more precursor gases in situ or via multiple channel gas injection systems, thereby making the production of precise, reproducible alloy compositions difficult. Promising recent efforts to address this problem have involved the use of multi-centred, heterometallic FEBID precursor species. In this vein, we present here a study of low-energy electron interactions with cyclopentadienyl iron dicarbonyl manganese pentacarbonyl ((η5-Cp)Fe(CO)2Mn(CO)5), a bimetallic species with a polyhapto ligand (Cp) and seven terminal carbonyl ligands. Gas phase studies and coupled cluster calculations of observed low-energy electron-induced reactions were conducted in order to predict the performance of this precursor in FEBID. In dissociative electron attachment, we find single CO loss and cleavage of the Fe-Mn bond, leading to the formation of [Mn(CO)5]-, to be the two dominant channels. Contributions through further CO loss from the intact core and the formation of [Mn(CO)4]- are minor channels. In dissociative ionization (DI), the fragmentation is significantly more extensive and the DI spectra are dominated by fragments formed through the loss of 5 and 6 CO ligands, and fragments formed through cleavage of the Fe-Mn bond accompanied by substantial CO loss. The gas phase fragmentation channels observed are discussed in relation to the underlying processes and their energetics, and in context to related surface studies and the likely performance of this precursor in FEBID.

Nitrogen losses to the environment following food-based digestate and compost applications to agricultural land.

The anaerobic digestion of food waste for energy recovery produces a nutrient-rich digestate which is a valuable source of crop available nitrogen (N). As with any 'new' material being recycled to agricultural land it is important to develop best management practices that maximise crop available N supply, whilst minimising emissions to the environment. In this study, ammonia (NH3) and nitrous oxide (N2O) emissions to air and nitrate (NO3-) leaching losses to water following digestate, compost and livestock manure applications to agricultural land were measured at 3 sites in England and Wales. Ammonia emissions were greater from applications of food-based digestate (c.40% of total N applied) than from livestock slurry (c.30% of total N applied) due to its higher ammonium-N content (mean 5.6 kg/t compared with 1-2 kg/t for slurry) and elevated pH (mean 8.3 compared with 7.7 for slurry). Whilst bandspreading was effective at reducing NH3 emissions from slurry compared with surface broadcasting it was not found to be an effective mitigation option for food-based digestate in this study. The majority of the NH3 losses occurred within 6 h of spreading highlighting the importance of rapid soil incorporation as a method for reducing NH3 emissions. Nitrous oxide losses from food-based digestates were low, with emission factors all less than the IPCC default value of 1% (mean 0.45 ± 0.15%). Overwinter NO3- leaching losses from food-based digestate were similar to those from pig slurry, but much greater than from pig farmyard manure or compost. Both gaseous N losses and NO3- leaching from green and green/food composts were low, indicating that, in these terms, compost can be considered as an 'environmentally benign' material. These findings have been used in the development of best practice guidelines which provide a framework for the responsible use of digestates and composts in agriculture.

Low energy electron-induced decomposition of (η3-C3H5)Ru(CO)3Br, a potential focused electron beam induced deposition precursor with a heteroleptic ligand set.

Here we describe in detail low energy electron induced fragmentation of a potential focused electron beam induced deposition (FEBID) precursor, π-allyl ruthenium tricarbonyl bromide, i.e. (η3-C3H5)Ru(CO)3Br, specially designed to allow comparison of the effect of different ligands on the efficiency of low energy electron induced fragmentation of FEBID precursors. Specifically, we discuss the efficiency of dissociative electron attachment (DEA) and dissociative ionization (DI) with respect to electron-induced removal of the allyl, bromide and carbonyl ligands. We place this in perspective with a previous surface study on the same precursor and we propose a design strategy for FEBID precursor molecules to increase their susceptibility towards DEA.