Modelling spatial and inter-annual variations of nitrous oxide emissions from UK cropland and grasslands using DailyDayCent

This work contributes to the Defra funded projects AC0116: ‘Improving the nitrous oxide inventory’, and AC0114: ‘Data Synthesis, Management and Modelling’. Funding for this work was provided by the UK Department for Environment, Food and Rural Affairs (Defra) AC0116 and AC0114, the Department of Agriculture, Environment and Rural Affairs for Northern Ireland, the Scottish Government and the Welsh Government. Rothamsted Research receives strategic funding from the Biotechnology and Biological Sciences Research Council. This study also contributes to the projects: N-Circle (BB/N013484/1), U-GRASS (NE/M016900/1) and GREENHOUSE (NE/K002589/1).Peer reviewedPublisher PD

The contribution of cattle urine and dung to nitrous oxide emissions: Quantification of country specific emission factors and implications for national inventories

Publication history: Accepted - 10 April 2018; Published online - 24 April 2018.Urine patches and dung pats from grazing livestock create hotspots for production and emission of the greenhouse gas, nitrous oxide (N2O), and represent a large proportion of total N2O emissions in many national agricultural greenhouse gas inventories. As such, there is much interest in developing country specific N2O emission factors (EFs) for excretal nitrogen (EF3, pasture, range and paddock) deposited during gazing. The aims of this study were to generate separate N2O emissions data for cattle derived urine and dung, to provide an evidence base for the generation of a country specific EF for the UK from this nitrogen source. The experiments were also designed to determine the effects of site and timing of application on emissions, and the efficacy of the nitrification inhibitor, dicyandiamide (DCD) on N2O losses. This co-ordinated set of 15 plot-scale, year-long field experiments using static chambers was conducted at five grassland sites, typical of the soil and climatic zones of grazed grassland in the UK. We show that the average urine and dung N2O EFs were 0.69% and 0.19%, respectively, resulting in a combined excretal N2O EF (EF3), of 0.49%, which is b25% of the IPCC default EF3 for excretal returns from grazing cattle. Regression analysis suggests that urineN2O EFs were controlledmore by composition than was the case for dung, whilst dung N2O EFs were more related to soil and environmental factors. The urine N2O EF was significantly greater from the site in SW England, and significantly greater from the early grazing season urine application than later applications. Dycandiamide reduced the N2O EF fromurine patches by an average of 46%. The significantly lower excretal EF3 than the IPCC default has implications for the UK's national inventory and for subsequent carbon footprinting of UK ruminant livestock productsThe authors are grateful to the UK Department for Environment, Food and Rural Affairs (Defra), the Department of Agriculture and Rural Development (now the Department of Agriculture, Environment and Rural Affairs) in Northern Ireland, and the Scottish Government and the Welsh Government for financial support via the InveN2Ory project (AC0116). The work by Rothamsted Research was additionally supported by the Biotechnology and Biological Sciences Research Council (BBS/E/C/000I0320). We would also like to thank Jon Moorby (IBERS, Wales, UK), Reading University, SRUC (Scotland, UK) and Conrad Ferris (AFBI, Northern Ireland, UK), for provision of cattle urine and dung

Reducing nitrous oxide emissions by changing N fertiliser use from calcium ammonium nitrate (CAN) to urea based formulations

This research was financially supported under the National Development Plan, through the Research Stimulus Fund, administered by the Department of Agriculture, Food and the Marine (Grant numbers RSF10-/RD/SC/716 and RSF11S138) and from the Department of Agriculture and Rural Development (Ref: DARD Evidence and Innovation project 13/04/06) for Northern Ireland. The first author gratefully acknowledges funding received from the Teagasc Walsh Fellowship Scheme (Ref: 2012005).peer-reviewedThe accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food demand, is the primary driver for increased atmospheric concentrations of nitrous oxide (N2O). The IPCC default emission factor (EF) for N2O from soils is 1% of the N applied, irrespective of its form. However, N2O emissions tend to be higher from nitrate-containing fertilisers e.g. calcium ammonium nitrate (CAN) compared to urea, particularly in regions, which have mild, wet climates and high organic matter soils. Urea can be an inefficient N source due to NH3 volatilisation, but nitrogen stabilisers (urease and nitrification inhibitors) can improve its efficacy. This study evaluated the impact of switching fertiliser formulation from calcium ammonium nitrate (CAN) to urea-based products, as a potential mitigation strategy to reduce N2O emissions at six temperate grassland sites on the island of Ireland. The surface applied formulations included CAN, urea and urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N2O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N2O emission factor (EF) from CAN averaged 1.49% overall sites, but was highly variable, ranging from 0.58% to 3.81. Amending urea with NBPT, to reduce ammonia volatilisation, resulted in an average EF of 0.40% (ranging from 0.21 to 0.69%)-compared to an average EF of 0.25% for urea (ranging from 0.1 to 0.49%), with both fertilisers significantly lower and less variable than CAN. Cumulative N2O emissions from urea amended with both NBPT and DCD were not significantly different from background levels. Switching from CAN to stabilised urea formulations was found to be an effective strategy to reduce N2O emissions, particularly in wet, temperate grassland.Department of Agriculture and Rural Development for Northern IrelandTeagasc Walsh Fellowship ProgrammeDepartment of Agriculture, Food and the Marin

Carbon disulfide removal by zero valent iron

The use of zero valent iron (Fe-0) for the remediation of water contaminated with carbon disulfide (CS2), a common groundwater contaminant, has been evaluated in this study. Mineralogical analysis of Fe-0 filings and polished Fe-0 cross-sections indicates that iron sulfide is formed due to the removal of carbon disulfide from solution by Fe-0. The kinetics of CS2 removal by Fe-0 was examined through both batch and column testing, and it is demonstrated that CS2 is removed rapidly from solution. A linear relationship was observed, through batch testing, between the pseudofirst-order rate constant (k(obs)) and the surface area concentration of Fe-0 (rho a). Data obtained from kinetic batch tests performed at four temperature levels conformed to the Arrhenius equation, anc the calculated apparent activation energy (E-a) was 37 +/- 2.3 kJ mol(-1), indicating that the kinetics of CS2 removal by Fe-0 is controlled by a chemical surface reaction. The temperature correction factors for CS2 from a reference of 25 degrees C were x 1.4 for 18 degrees C, x 1.7 for 15 degrees C, x 2.0 for 12 degrees C, and x 2.3 for 9 degrees C. Surface area normalization of kob, obtained through batch and column testing gives specific reaction rate constants (k(SA)) within 1 order of magnitude, indicating that kSA values are useful as a general descriptor of CS2-Fe-0 reaction kinetics and that these values provide a clear starting point for design calculations prior to commencing site-specific treatability studies for permeable reactive barrier design

Numerical modeling for remediation of contaminated land and groundwater

This article discusses numerical modeling for remediation of contaminated land and groundwater