Agriculture currently accounts for 28% of national greenhouse gas emissions in Ireland. Nitrous o... more Agriculture currently accounts for 28% of national greenhouse gas emissions in Ireland. Nitrous oxide (N 2 O) emissions from agricultural soils account for 38% of this total. A 2-year study was conducted, using the chamber technique on a fertilized and grazed grassland to quantify the effect of fertilizer application rate, soil and meteorological variables on N 2 O emissions. Three N fertilizer regimes (0, 225 & 390 kg N ha -1 ) were imposed with three replicates of each treatment. Nitrogen fertilizer was applied as urea (46% N) in spring with calcium ammonium nitrate (CAN-26% N) applied in the summer (June-September). Rotational grazing was practiced using steers. Nitrous oxide emissions arising from the unfertilized plots (0 N) were consistently low. Emissions from the N-fertilized plots (225 & 390 kg N ha -1 ) were concen-trated in relatively short periods (1-2 weeks) following fertilizer applications and grazing, with marked differences between treatments, relative patterns and magnitudes of emissions at different times of the year and between years. Variation in N 2 O emissions throughout both years was pronounced with mean coefficients of variation of 116% in year 1 and 101% in year 2. The study encompassed two climatologically contrasting years. As a result the N 2 O-N loss, as a percent of the N applied in the cooler and wetter 2002 (0.2-2.0%), were similar to those used for N-fertilized grasslands under the Intergovernmental Panel on Climate Change (IPCC) N 2 O emission inventory calculation methodology (1.25% ± 1). In contrast, the percentage losses in the warmer and drier 2003 (3.5-7.2%) were substantially higher.
This paper describes an empirical model of soil-evolved nitrous oxide emissions inferred from dat... more This paper describes an empirical model of soil-evolved nitrous oxide emissions inferred from data gathered in a 2-year rotational grazing experiment investigating emissions from a fertilised and grazed grassland site. The model was used to simulate daily and annual emissions for the 9-year period between 1994 and 2002 under different possible fertiliser application scenarios. As the model only requires a small number of commonly available site-specific data inputs, this facilitates its use at different geographical locations. This is the first empirical modelling of daily fluxes to give estimates of annual emissions. Results reveal a high interannual variability of emissions that increases with the amount of nitrogen fertiliser applied. Simulation using the model for the period 1994-2002 indicated that higher soil moisture status on the day of fertiliser N application increased the average annual nitrous oxide emissions.
A field experiment was undertaken to compare nitrous oxide (N 2 O) emissions from a grazed pastur... more A field experiment was undertaken to compare nitrous oxide (N 2 O) emissions from a grazed pasture receiving three different nitrogen (N) fertilizer application rates (0, 225 and 390 kg ha À 1 ) and to identify the effects of controlling variables over a 2-year period (2002 and 2003). The N 2 O-N losses, expressed as a percent of the N applied, in the cooler and wetter 2002 were 0.2-2.0%. In contrast, the percentage loss in the warmer and drier 2003 (3.5-7.2%) were substantially higher. An empirical model was developed to enable simulations and scenario analysis to be undertaken, assuming various climatic scenarios and N fertilizer application regimes. Results suggest that inter-annual variability due to climatic factors increases with the amount of applied fertilizer N and decreases with frequency of application. D
ABSTRACT With the current focus of policy action on climate change mitigation, it is important to... more ABSTRACT With the current focus of policy action on climate change mitigation, it is important to investigate possible negative side effects of climate change policies on air pollutants. A 34% increase in CO2 emissions from private cars in Ireland over the period 2000-2008 prompted a change in private car taxation in 2008 to incentivise the purchase of lower CO2 emitting cars. The impact has been successful and the measure has accelerated the dieselisation of the car fleet. This however, raises an important question, namely how does the dieselisation of the car fleet affect NOx emissions? This paper combines two models to address this question, a car stock model to generate activity data (future composition and activity of Ireland's car stock) and the COPERT model to quantify the NOx emissions generated in the period 2008-2020. Previous analysis shows that the CO2 taxation policy measure is anticipated to deliver a 7% reduction in private car related CO2 emissions in 2020 compared with a baseline pre-tax scenario. The results here show that NOx emissions decrease in all scenarios, but a lesser degree of reduction is achieved due to dieselisation, with NOx emissions in the post-tax scenario 28% higher than the pre-tax scenario in 2020.
present a model which relates waste generation to economic and demographic drivers referred to he... more present a model which relates waste generation to economic and demographic drivers referred to here as the ESRI Model. The ESRI model provides estimates of total waste diverted to landfill and has been extended to estimate resultant methane generation from this waste. Unfortunately, the paper contains a number of inaccuracies that seriously undermine the conclusions that are drawn. This note aims to address any confusion which may arise from this publication and to correct a number of the main inaccuracies.
Agriculture plays a vital role in the Irish economy, accounting for 3.5% of the gross domestic pr... more Agriculture plays a vital role in the Irish economy, accounting for 3.5% of the gross domestic product (GDP) in 2000. Grassland farming and, in particular, cattle rearing and dairying accounts for more than 90% of farming activity. In addition, there have been significant increases in the number of sheep, pigs and poultry over the last twenty years. As a consequence, gaseous nitrogen (N) emissions have shown a clear upward trend. Following the adoption of the United Nations Economic Commission for Europe (UNECE) Gothenburg protocol (Protocol to the 1979 convention on longrange transboundary air pollution to abate acidification, eutrophication and ground-level ozone. United Nations Economic Commissions for Europe (UNECE), Geneva.), Ireland has to achieve a 9% reduction in national ammonia (NH 3 ) emissions between 1990 and 2010. The agricultural sector accounts for virtually all NH 3 emissions in Ireland. It is on this basis that a new inventory of NH 3 emissions from agriculture has been produced. This paper describes the adoption of the UK national inventory model to Irish agricultural systems, the results of model calculations and the measures available to enable compliance with national targets and areas within the inventory, which require further investigation. Estimated total emissions from Irish agriculture were 89.9 and 91.8 kt NH 3 -N for 1991 and 2010, respectively. Cattle farming accounts for more than 75% of total emissions. The largest emission factors found included 46.9 g NH 3 -N lu À1 d À1 for cattle housing, 29.5 g NH 3 -N lu À1 d À1 for pig housing and 150 g NH 3 -N lu À1 d À1 for housed broilers (lu being equivalent to 500 kg live weight). In addition, model predictions for the year 2010 showed that without any abatement strategies being implemented, NH 3 emissions would exceed the agreed national emission reduction target by 12%. It was also found that strategies for reducing emissions from the land spreading of manure offer the greatest potential to achieve target levels. r
Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospher... more Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospheric N2O. It is hence crucial to explore various solutions including farm nitrogen (N) management to mitigate N2O emissions without sacrificing farm profitability and food supply. This paper reviews major N management practices to lower N2O emission from grassland-based agriculture. Restricted grazing by reducing grazing time is an effective way to decrease N2O emissions from excreta patches. Balancing the protein-to-energy ratios in the diets of ruminants can also decrease N2O emissions from excreta patches. Among the managements of synthetic fertilizer N application, only adjusting fertilizer N rate and slow-released fertilizers are proven to be effective in lowering N2O emissions. Use of bedding materials may increase N2O emissions from animal houses. Manure storage as slurry, manipulating slurry pH to values lower than 6 and storage as solid manure under anaerobic conditions help to reduce N2O emissions during manure storage stage. For manure land application, N2O emissions can be mitigated by reducing manure N inputs to levels that satisfy grass needs. Use of nitrification inhibitors can substantially lower N2O emissions associated with applications of fertilizers and manures and from urine patches. N2O emissions from legume based grasslands are generally lower than fertilizer-based systems. In conclusion, effective measures should be taken at each step during N flow or combined options should be used in order to mitigate N2O emission at the farm level.
Agriculture currently accounts for 28% of national greenhouse gas emissions in Ireland. Nitrous o... more Agriculture currently accounts for 28% of national greenhouse gas emissions in Ireland. Nitrous oxide (N 2 O) emissions from agricultural soils account for 38% of this total. A 2-year study was conducted, using the chamber technique on a fertilized and grazed grassland to quantify the effect of fertilizer application rate, soil and meteorological variables on N 2 O emissions. Three N fertilizer regimes (0, 225 & 390 kg N ha -1 ) were imposed with three replicates of each treatment. Nitrogen fertilizer was applied as urea (46% N) in spring with calcium ammonium nitrate (CAN-26% N) applied in the summer (June-September). Rotational grazing was practiced using steers. Nitrous oxide emissions arising from the unfertilized plots (0 N) were consistently low. Emissions from the N-fertilized plots (225 & 390 kg N ha -1 ) were concen-trated in relatively short periods (1-2 weeks) following fertilizer applications and grazing, with marked differences between treatments, relative patterns and magnitudes of emissions at different times of the year and between years. Variation in N 2 O emissions throughout both years was pronounced with mean coefficients of variation of 116% in year 1 and 101% in year 2. The study encompassed two climatologically contrasting years. As a result the N 2 O-N loss, as a percent of the N applied in the cooler and wetter 2002 (0.2-2.0%), were similar to those used for N-fertilized grasslands under the Intergovernmental Panel on Climate Change (IPCC) N 2 O emission inventory calculation methodology (1.25% ± 1). In contrast, the percentage losses in the warmer and drier 2003 (3.5-7.2%) were substantially higher.
This paper describes an empirical model of soil-evolved nitrous oxide emissions inferred from dat... more This paper describes an empirical model of soil-evolved nitrous oxide emissions inferred from data gathered in a 2-year rotational grazing experiment investigating emissions from a fertilised and grazed grassland site. The model was used to simulate daily and annual emissions for the 9-year period between 1994 and 2002 under different possible fertiliser application scenarios. As the model only requires a small number of commonly available site-specific data inputs, this facilitates its use at different geographical locations. This is the first empirical modelling of daily fluxes to give estimates of annual emissions. Results reveal a high interannual variability of emissions that increases with the amount of nitrogen fertiliser applied. Simulation using the model for the period 1994-2002 indicated that higher soil moisture status on the day of fertiliser N application increased the average annual nitrous oxide emissions.
A field experiment was undertaken to compare nitrous oxide (N 2 O) emissions from a grazed pastur... more A field experiment was undertaken to compare nitrous oxide (N 2 O) emissions from a grazed pasture receiving three different nitrogen (N) fertilizer application rates (0, 225 and 390 kg ha À 1 ) and to identify the effects of controlling variables over a 2-year period (2002 and 2003). The N 2 O-N losses, expressed as a percent of the N applied, in the cooler and wetter 2002 were 0.2-2.0%. In contrast, the percentage loss in the warmer and drier 2003 (3.5-7.2%) were substantially higher. An empirical model was developed to enable simulations and scenario analysis to be undertaken, assuming various climatic scenarios and N fertilizer application regimes. Results suggest that inter-annual variability due to climatic factors increases with the amount of applied fertilizer N and decreases with frequency of application. D
ABSTRACT With the current focus of policy action on climate change mitigation, it is important to... more ABSTRACT With the current focus of policy action on climate change mitigation, it is important to investigate possible negative side effects of climate change policies on air pollutants. A 34% increase in CO2 emissions from private cars in Ireland over the period 2000-2008 prompted a change in private car taxation in 2008 to incentivise the purchase of lower CO2 emitting cars. The impact has been successful and the measure has accelerated the dieselisation of the car fleet. This however, raises an important question, namely how does the dieselisation of the car fleet affect NOx emissions? This paper combines two models to address this question, a car stock model to generate activity data (future composition and activity of Ireland's car stock) and the COPERT model to quantify the NOx emissions generated in the period 2008-2020. Previous analysis shows that the CO2 taxation policy measure is anticipated to deliver a 7% reduction in private car related CO2 emissions in 2020 compared with a baseline pre-tax scenario. The results here show that NOx emissions decrease in all scenarios, but a lesser degree of reduction is achieved due to dieselisation, with NOx emissions in the post-tax scenario 28% higher than the pre-tax scenario in 2020.
present a model which relates waste generation to economic and demographic drivers referred to he... more present a model which relates waste generation to economic and demographic drivers referred to here as the ESRI Model. The ESRI model provides estimates of total waste diverted to landfill and has been extended to estimate resultant methane generation from this waste. Unfortunately, the paper contains a number of inaccuracies that seriously undermine the conclusions that are drawn. This note aims to address any confusion which may arise from this publication and to correct a number of the main inaccuracies.
Agriculture plays a vital role in the Irish economy, accounting for 3.5% of the gross domestic pr... more Agriculture plays a vital role in the Irish economy, accounting for 3.5% of the gross domestic product (GDP) in 2000. Grassland farming and, in particular, cattle rearing and dairying accounts for more than 90% of farming activity. In addition, there have been significant increases in the number of sheep, pigs and poultry over the last twenty years. As a consequence, gaseous nitrogen (N) emissions have shown a clear upward trend. Following the adoption of the United Nations Economic Commission for Europe (UNECE) Gothenburg protocol (Protocol to the 1979 convention on longrange transboundary air pollution to abate acidification, eutrophication and ground-level ozone. United Nations Economic Commissions for Europe (UNECE), Geneva.), Ireland has to achieve a 9% reduction in national ammonia (NH 3 ) emissions between 1990 and 2010. The agricultural sector accounts for virtually all NH 3 emissions in Ireland. It is on this basis that a new inventory of NH 3 emissions from agriculture has been produced. This paper describes the adoption of the UK national inventory model to Irish agricultural systems, the results of model calculations and the measures available to enable compliance with national targets and areas within the inventory, which require further investigation. Estimated total emissions from Irish agriculture were 89.9 and 91.8 kt NH 3 -N for 1991 and 2010, respectively. Cattle farming accounts for more than 75% of total emissions. The largest emission factors found included 46.9 g NH 3 -N lu À1 d À1 for cattle housing, 29.5 g NH 3 -N lu À1 d À1 for pig housing and 150 g NH 3 -N lu À1 d À1 for housed broilers (lu being equivalent to 500 kg live weight). In addition, model predictions for the year 2010 showed that without any abatement strategies being implemented, NH 3 emissions would exceed the agreed national emission reduction target by 12%. It was also found that strategies for reducing emissions from the land spreading of manure offer the greatest potential to achieve target levels. r
Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospher... more Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospheric N2O. It is hence crucial to explore various solutions including farm nitrogen (N) management to mitigate N2O emissions without sacrificing farm profitability and food supply. This paper reviews major N management practices to lower N2O emission from grassland-based agriculture. Restricted grazing by reducing grazing time is an effective way to decrease N2O emissions from excreta patches. Balancing the protein-to-energy ratios in the diets of ruminants can also decrease N2O emissions from excreta patches. Among the managements of synthetic fertilizer N application, only adjusting fertilizer N rate and slow-released fertilizers are proven to be effective in lowering N2O emissions. Use of bedding materials may increase N2O emissions from animal houses. Manure storage as slurry, manipulating slurry pH to values lower than 6 and storage as solid manure under anaerobic conditions help to reduce N2O emissions during manure storage stage. For manure land application, N2O emissions can be mitigated by reducing manure N inputs to levels that satisfy grass needs. Use of nitrification inhibitors can substantially lower N2O emissions associated with applications of fertilizers and manures and from urine patches. N2O emissions from legume based grasslands are generally lower than fertilizer-based systems. In conclusion, effective measures should be taken at each step during N flow or combined options should be used in order to mitigate N2O emission at the farm level.
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