Impact of fertiliser nitrogen formulation, and N stabilisers on nitrous oxide emissions in spring barley

The application of nitrogen (N) fertilisers to agricultural soils is a major source of nitrous oxide (N2O) emissions. The Intergovernmental Panel on Climate Change (IPCC) has set a default emission factor of 1% (EF1) for N fertiliser applied to managed agricultural soils. This value does not differentiate between different N fertiliser formulations or rates of N application. The objective of this field study under spring barley was to determine N2O EF’s for different N fertiliser formulations including urea and urea stabilised with the nitrification inhibitor dicyandiamide (DCD) and/or the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and to evaluate their N2O loss abatement potential relative to calcium ammonium nitrate (CAN). The highest EF1 measured was 0.49% for CAN which was less than half the IPCC default value of 1%. While the urease inhibitor did not reduce emissions relative to CAN; the nitrification inhibitor significantly reduced emissions compared to CAN with EF1 as low as 0.00% for a typical spring barley site. There was no significant impact of CAN or urea application rate on EF1 but there was a significant negative relationship observed for urea in 2013. The study highlights the importance of generating higher Tier emission factors in terms of fertiliser type for use in national inventories

Nitrogen fertilisers with urease inhibitors reduce nitrous oxide and ammonia losses, while retaining yield in temperate grassland

peer-reviewedNitrogen fertilisation, although a cornerstone of modern agricultural production, negatively impacts the environment through gaseous losses of nitrous oxide (N2O), a potent greenhouse gas (GHG), and ammonia (NH3), a known air pollutant. The aim of this work was to assess the feasibility of urea treated with urease inhibitors to reduce gaseous N losses in temperate grassland, while maintaining or improving productivity compared to conventional fertiliser formulations. Urease inhibitors were N-(n-butyl)-thiophosphoric triamide (NBPT) (urea + NBPT) and N-(n-propyl)-thiophosphoric triamide (NPPT) (urea+ NBPT + NPPT), while conventional fertilisers were urea and calcium ammonium nitrate (CAN). N2O emission factors were 0.06%, 0.07%, 0.09% and 0.58% from urea + NBPT, urea, urea + NBPT + NPPT and CAN, respectively, with CAN significantly higher than all the urea formulations, which were not significantly different from each other. Ammonia loss measured over one fertiliser application was significantly larger from urea, at 43%, compared with other formulations at 13.9%, 13.8% and 5.2% from urea + NBPT, urea + NBPT + NPPT and CAN, respectively. Changing fertiliser formulation had no significant impact on grass yield or N uptake in four out of five harvests. In the last harvest urea + NBPT significantly out-yielded urea, but not CAN or urea + NBPT + NPPT. Overall, urea treated with either one or both urease inhibitors significantly reduced emissions of N2O and NH3, while preserving yield quantity and quality. Therefore, changing fertiliser formulation to these products should be encouraged as a strategy to reduce GHG and air pollution from agricultural practices in temperate climate

Increasing soil pH reduces fertiliser derived N2O emissions in intensively managed temperate grassland

peer-reviewedSoil pH is generally considered a master variable, controlling a wide range of physical, chemical and biological properties, including a significant effect on microbial processes responsible for production and consumption of nitrous oxide (N2O), a potent greenhouse gas. Evidence of this pH impact on microbial denitrification mainly stems from observations in controlled laboratory experiments, while the results from field studies are mainly short-term, more variable and circumstantial. Soil pH is also one of the main factors controlling the availability of soil phosphorous (P), which has been also linked with N2O emissions. Here, we utilised an existing intensive grassland liming and P trial to investigate the effect of longer-term lime and P management and their interaction on N2O emissions and grassland productivity. The treatment plots were subject to different liming and P fertilisation strategies over 8 years and had a wide gradient of soil pH (5.1–6.9) and extractable P (2.3–8.3 mg kg−1). All plots received a total of 300 kg ha−1 of fertiliser nitrogen (N), applied in 8 splits across the growing season. N2O emissions, soil mineral N and grass yields were measured over 12-month period. We found a negative linear relationship between soil pH and cumulative N2O emissions, with a decrease in N2O emissions up to 39 % from limed plots compared to the unlimed control. The same effect was observed in relation to N2O emission factors and yield-scaled N2O emissions. Extractable soil P content had positive effect on yields, but no effect of P or P and pH interaction was observed in terms of direct N2O emissions or yield-scaled N2O emissions. We estimated that the increase in soil pH of grasslands in Ireland over the last 12 years potentially reduced national N2O emissions by 95 Gg CO2-eq yr−1, with potential for a further reduction by up to 254 Gg CO2-eq yr−1 if all the remaining acidic soils are brought up to optimal pH

A Response to the Draft National Mitigation Plan. Teagasc submission to the Department of Communications, Climate Action & theEnvironment

Teagasc SubmissionThis submission details the mitigation potential of agriculture to shortly be published as an update to the Marginal Abatement Cost Curve (MACC) for Agriculture and and describes how the MACC mitigation strategies relate to the measures in the National Mitigation Plan

Urease and Nitrification Inhibitors—As Mitigation Tools for Greenhouse Gas Emissions in Sustainable Dairy Systems: A Review

peer-reviewedCurrently, nitrogen fertilizers are utilized to meet 48% of the total global food demand. The demand for nitrogen fertilizers is expected to grow as global populations continue to rise. The use of nitrogen fertilizers is associated with many negative environmental impacts and is a key source of greenhouse and harmful gas emissions. In recent years, urease and nitrification inhibitors have emerged as mitigation tools that are presently utilized in agriculture to prevent nitrogen losses and reduce greenhouse and harmful gas emissions that are associated with the use of nitrogen-based fertilizers. Both classes of inhibitor work by different mechanisms and have different physiochemical properties. Consequently, each class must be evaluated on its own merits. Although there are many benefits associated with the use of these inhibitors, little is known about their potential to enter the food chain, an event that may pose challenges to food safety. This phenomenon was highlighted when the nitrification inhibitor dicyandiamide was found as a residual contaminant in milk products in 2013. This comprehensive review aims to discuss the uses of inhibitor technologies in agriculture and their possible impacts on dairy product safety and quality, highlighting areas of concern with regards to the introduction of these inhibitor technologies into the dairy supply chain. Furthermore, this review discusses the benefits and challenges of inhibitor usage with a focus on EU regulations, as well as associated health concerns, chemical behavior, and analytical detection methods for these compounds within milk and environmental matrices.Department of Agriculture, Food and the Marine, Irelan

Can the agronomic performance of urea equal calcium ammonium nitrate across nitrogen rates in temperate grassland?

Department of Agriculture, Environment and Rural Affairs in Northern Ireland, the Teagasc Walsh Fellowship Schemepeer-reviewedIn temperate grassland, urea has been shown to have lower nitrous oxide emissions compared to ammonium nitrate-based fertilizer and is less expensive. However, nitrogen (N) loss via ammonia volatilization from urea raises questions regarding yield performance and efficiency. This study compares the yield and N offtake of grass fertilized with urea, calcium ammonium nitrate (CAN) and urea treated with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) at six site-years. Five annual fertilizer N rates (100–500 kg N/ha) were applied in five equal splits of 20–100 kg N/ha during the growing season. On average, urea produced slightly better yields than CAN in spring (103.5% of CAN yield) and slightly poorer yields in summer (98.4% of CAN yield). There was no significant difference in annual grass yield between urea, CAN and urea + NBPT. Urea had the lowest cost per tonne of DM grass yield produced. However, the urea treatment had lower N offtake than CAN and this difference was more pronounced as the N rate increased. There was no difference in N offtake between urea + NBPT and CAN. While this study shows that urea produced yields comparable to CAN, urea apparent fertilizer N recovery (AFNR) tends to be lower. Urea selection in place of CAN will increase national ammonia emissions which is problematic for countries with targets to reduce ammonia emissions. Promisingly, NBPT allows the agronomic performance of urea to consistently equal CAN across N rates by addressing the ammonia loss limitations of urea.Department of Agriculture, Environment and Rural Affairs in Northern IrelandTeagasc Walsh Fellowship ProgrammeDepartment of Agriculture, Food and the Marin

Scenarios to limit environmental nitrogen losses from dairy expansion

peer-reviewedIncreased global demand for dairy produce and the abolition of EU milk quotas have resulted in expansion in dairy production across Europe and particularly in Ireland. Simultaneously, there is increasing pressure to reduce the impact of nitrogen (N) losses to air and groundwater on the environment. In order to develop grassland management strategies for grazing systems that meet environmental targets and are economically sustainable, it is imperative that individual mitigation measures for N efficiency are assessed at farm system level. To this end, we developed an excel-based N flow model simulating an Irish grass-based dairy farm, to evaluate the effect of farm management on N efficiency, N losses, production and economic performance. The model was applied to assess the effect of different strategies to achieve the increased production goals on N utilization, N loss pathways and economic performance at farm level. The three strategies investigated included increased milk production through increased grass production, through increased concentrate feeding and by applying a high profit grass-based system. Additionally, three mitigation measures; low ammonia emission slurry application, the use of urease and nitrification inhibitors and the combination of both were applied to the three strategies. Absolute N emissions were higher for all intensification scenarios (up to 124 kg N ha−1) compared to the baseline (80 kg N ha−1) due to increased animal numbers and higher feed and/or fertiliser inputs. However, some intensification strategies showed the potential to reduce the emissions per ton milk produced for some of the N-loss pathways. The model showed that the assessed mitigation measures can play an important role in ameliorating the increased emissions associated with intensification, but may not be adequate to entirely offset absolute increases. Further improvements in farm N use efficiency and alternatives to mineral fertilisers will be required to decouple production from reactive N emissions

Electrocardiographic features of immune checkpoint inhibitor associated myocarditis

Background Myocarditis is a highly morbid complication of immune checkpoint inhibitor (ICI) use that remains inadequately characterized. The QRS duration and the QTc interval are standardized electrocardiographic measures that are prolonged in other cardiac conditions; however, there are no data on their utility in ICI myocarditis. Methods From an international registry, ECG parameters were compared between 140 myocarditis cases and 179 controls across multiple time points (pre-ICI, on ICI prior to myocarditis, and at the time of myocarditis). The association between ECG values and major adverse cardiac events (MACE) was also tested. Results Both the QRS duration and QTc interval were similar between cases and controls prior to myocarditis. When compared with controls on an ICI (93±19 ms) or to baseline prior to myocarditis (97±19 ms), the QRS duration prolonged with myocarditis (110±22 ms, p<0.001 and p=0.009, respectively). In contrast, the QTc interval at the time of myocarditis (435±39 ms) was not increased compared with pre-myocarditis baseline (422±27 ms, p=0.42). A prolonged QRS duration conferred an increased risk of subsequent MACE (HR 3.28, 95% CI 1.98 to 5.62, p<0.001). After adjustment, each 10 ms increase in the QRS duration conferred a 1.3-fold increase in the odds of MACE (95% CI 1.07 to 1.61, p=0.011). Conversely, there was no association between the QTc interval and MACE among men (HR 1.33, 95% CI 0.70 to 2.53, p=0.38) or women (HR 1.48, 95% CI 0.61 to 3.58, p=0.39). Conclusions The QRS duration is increased in ICI myocarditis and is associated with increased MACE risk. Use of this widely available ECG parameter may aid in ICI myocarditis diagnosis and risk-stratification

An Analysis of the Cost of the Abatement of Ammonia Emissions in Irish Agriculture to 2030

peer-reviewedThis analysis quantifies the potential to abate national ammonia (NH3) emissions up to 2030. This report is an updated marginal abatement cost curve (MACC) analysis where Teagasc has quantified the abatement potential of a range of ammonia mitigation measures, as well as their associated costs/benefits (see Lanigan et al. 2015 for previous analysis). The objective of this analysis is to quantify the extent and costs associated with meeting future ammonia emission targets that were negotiated as part of the amended Clean Air Policy Package. The requirement to reduce ammonia emissions is urgent, both in terms of compliance with the National Emissions Ceilings Directive (NECD), and as a principal loss pathway for agricultural nitrogen (N). Improvement of N efficiency is a key focus for improving farm efficiency and sustainability as well as reducing the ammonia, nitrate and greenhouse gas (GHG) footprint of agriculture. This is particularly relevant in the context of the national strategies on the development of the agri-food sector: Food Wise 2025, Ag-food strategy 2030 and Ag-Climatise (currently under development) and the newly unveiled EU Farm to Fork Strategy, which is a part of the European Green Deal. Under the baseline scenario (S1), agricultural ammonia emissions are projected to increase by 9% (without any mitigation) by 2030 relative to 2005 levels. While these increases are small in comparison to the targeted increase in agricultural output, they will provide a major challenge to meeting emissions targets, particularly as agriculture comprises over 99% of national emissions. The analysis presented in this report seeks to quantify the ammonia mitigation potential under likely uptake pathways. This is not an exhaustive analysis of all mitigation measures, but represents an assessment of best available techniques, based on scientific, peer-reviewed research carried out by Teagasc and associated national and international research partners. Indeed, any future changes in the sector or in the national emission inventory calculations will require further analysis of the applicability of ammonia mitigation techniques, particularly in terms of housing and storage but also in the context of other reactive N1 emissions. It should also be noted that some mitigation measures, particularly those related to nitrogen application to soils, could result in either higher greenhouse gas emissions or higher nitrate leaching. Compared to a future where no mitigation measures are deployed to address emissions, by 2030 the average technical abatement2 potential was estimated to be approximately 15.26 kt NH3 at a net cost of €10.86 million per annum. However, it should be noted that the net cost (€10.86 million) is comprised of 6 measures that are cost negative (-€22.21 million) and 7 measures that are cost positive (€33.07) and that some of the cost negative measures are predicated on efficiency gains driven by best management practice adoption (e.g. liming and clover measures with associate chemical N reductions). Amongst the thirteen mitigation measures selected for this analysis, 80% of the mitigation potential can be achieved by the full implementation of the mitigation pathways for protected urea and low emission slurry spreading (LESS) techniques for bovines. It should be stressed that this is an assessment of the maximum abatement potential and realising this level of abatement in practice will be extremely challenging. Any increase in agricultural activity beyond the baseline scenario will increase absolute emissions. The level of mitigation achievable is based on the draft AgClimatise measures any delay or reduction in the uptake of these measures will reduce the mitigation achieved. It must also be ensured that all mitigation measures should, where possible, be synergistic with reductions in greenhouse gas emissions and N loss to water