mary harty | Queen's University Belfast (original) (raw)

Papers by mary harty

Energies

Data centres, though a necessary part of modern society, are being stigmatised for consuming vast... more Data centres, though a necessary part of modern society, are being stigmatised for consuming vast amounts of electricity for their operational and cooling needs. Due to Ireland’s reliance on fossil fuels to meet the increased energy demand of data centres, the data centres are contributing significantly to Ireland’s total carbon emissions. As much of this energy is expelled from data centres as waste heat energy, the potential for recycling some of this wasted heat energy was explored using environmentally friendly systems from recent publications. The recovered waste heat energy was applied in a vertical farming system, and the benefits of this waste heat to the vertical farm were analysed and quantified in two scenarios. Using conservative estimates, it was predicted that each vertical farm could be between 5–23% the size of the data centre and produce enough food to feed between 14–61 adults their daily calorie needs, and between 13–58 people their daily fresh produce requirement...

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Science of The Total Environment, 2016

Nitrogen

Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are... more Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are excessive, and N use efficiency (NUE) is low. N loss represents a significant economic loss to the farmer. NUE is difficult to quantify in real time because of the multiple chemical–biological–physical factors interacting. While there is much scientific understanding of N interactions in the plant–soil system, there is little formal expression of scientific knowledge in farm practice. The objective of this study was to clearly define the factors controlling NUE in wheat production, focusing on N inputs, flows, transformations, and outputs from the plant–soil system. A series of focus groups were conducted with professional agronomists and industry experts, and their technical information was considered alongside a structured literature review. To express this understanding, clear graphical representations are provided in the text. The analysis of the NUE processes revealed 16 management...

Journal of Biomedical Research & Environmental Sciences

Since 2010, solar Photovoltaic (PV) has been the single fastest growing power generation technolo... more Since 2010, solar Photovoltaic (PV) has been the single fastest growing power generation technology worldwide. However, given that the useful lifetime of a PV installation currently stands at 25 years and that current industry End-of-Life (EOL) management techniques, focus primarily on recycling and disposal, it has been estimated that by 2050, there will exist 78 million tonnes of hazardous solar PV waste. One potential solution that could aid in mitigating this impending environmental crisis, is determining whether or not the lifetime of commercial and residential solar PV installations can be elongated from the industry standard of 25 years to 50 years. Two novel solar PV ownership models, “The Cascading Tiered Commercial Ownership model” (CTCO) and “The Elongated Residential Ownership model” (ERO) have been created by projecting the technical outputs and economic Net Present Values (NPV) of a 60 kwp commercial and 4.8 kWp residential installation operated over a 50 as opposed to...

Geoderma, 2018

Biogeochemical models have the potential to provide insights into the key drivers of greenhouse g... more Biogeochemical models have the potential to provide insights into the key drivers of greenhouse gas (GHG) dynamics, and may be used in Tier 2 and 3 GHG emission reporting. Modelling nitrous oxide (N 2 O) emissions from agriculture, however, is still subject to large uncertainties. In the present study we analysed the performance of the three semi-mechanistic models, DailyDayCent (DayCent), DeNitrification-DeComposition (DNDC 9.4 and 9.5), and ECOSSE when simulating N 2 O fluxes from two different land uses (simulated grazing and spring barley) under a range of fertiliser types and application rates. Model performance was assessed using linear regression analysis, root mean square error (RMSE), and relative error. Monte Carlo analysis was carried out to assess the sensitivity of DayCent and ECOSSE to changes in the timing of management events. The results show high variability in model performance. The performance of each model was dependent on both site and treatment, with no model showing consistently good performance. When averaged across all sites and treatments DayCent simulations produced the lowest number of significant total and relative errors. When looking at the relationship between modelled and measured N 2 O fluxes, ECOSSE performed best with a significant relationship in 61.8% of all simulations and an average r 2 of 0.2. However, outputs from this model displayed the largest total and relative errors. Performance when simulating cumulative fluxes was generally poor. The Monte Carlo analysis showed that shifts in timing of management events by ± 7 days lead to annual N 2 O fluxes varying by 5.6 ± 7.6% and 2.8 ± 4.2% for grassland and cropland, respectively. However the impact of the timing of single events can lead to much larger responses in N 2 O emissions. The large variation in model performance suggests that further development and calibration is required before using models in GHG reporting.

Journal of Plant Nutrition, 1998

Urease inhibitors and nitrification inhibitors can reduce nitrogen (N) loss in agriculture soil. ... more Urease inhibitors and nitrification inhibitors can reduce nitrogen (N) loss in agriculture soil. However, the effect of inhibitors on soil N 2 O emissions under the drip irrigation system remains unclear. A pot and a field experiment with two inhibitors were conducted to explore how inhibitors regulate soil nitrogen transformation and N 2 O emissions. In the pot experiment, three treatments included control, urea, and urea + N-(n-butyl)thiophosphoric triamide (NBPT, urease inhibitor). In the field experiment, three treatments included control, urea, and urea + NBPT + 2-chloro-6-(trichloromethyl)pyridine (nitrapyrin, nitrification inhibitor). The urease inhibition rate in the treatment of urea + NBPT was 27.5% at the 14th day of incubation (pot experiment), and NH 4 +-N was significantly decreased by 37-64% compared with urea alone treatment. In the field experiment, the nitrification inhibition rate in the treatment of urea + NBPT + nitrapyrin was 47.7 and 63.9% on the 3rd day after fertilization at the wheat heading and filling stages, respectively. Compared to urea treatment, NO 3 −-N concentration in the double-inhibitor-added treatment was significantly decreased by 32 and 20% on the 5th day after fertilization at the heading and filling stages, respectively; N 2 O fluxes were also decreased by 30.9 and 33.3% at the two stages of wheat, respectively. In total, adding an inhibitor reduced N loss by 7.39 and 7.44% at the 14th and 35th day in the pot experiment and by 10.53 and 6.65% at the two growing stages of wheat in the field experiment, respectively. Path and correlation analysis showed that N 2 O emissions were significantly correlated with soil NO 3 − in both pot and field experiments.

Journal of Applied Microbiology, 2014

To investigate bacterial and fungal community structure during degradation of varying concentrati... more To investigate bacterial and fungal community structure during degradation of varying concentrations (0-5000 mg kg(-1) ) of the polycyclic aromatic hydrocarbon (PAH) fluoranthene in the presence or absence of tomato plants. Fluoranthene amended or unamended growing media, with or without a plant, were incubated in pots in a glasshouse for 30 days. Fluoranthene concentration was quantified using GC-FID, while bacterial and fungal community structure was investigated using trflp and arisa, respectively. The abundance of two ring hydroxylating dioxygenase genes was measured using qPCR. More fluoranthene was degraded in the presence of tomato plants at 500 and 5000 mg fluoranthene kg(-1) (P < 0·001), and it had a toxic effect on plant growth. Bacterial and fungal community composition in the rhizosphere was significantly different from that in nonrhizospheric and unplanted samples. The influence of fluoranthene on bacterial communities overcame that of the plant root such that community composition in rhizosphere and planted nonrhizospheric samples was broadly similar when fluoranthene was present. PAH-RHDα-GP genes were more abundant than PAH-RHDα-GN genes in all treatments. PAH-RHDα-GN abundance was unaffected by either PAH concentration or growing medium type, while the abundance of PAH-RHDα-GP was greatest in the rhizosphere. Plants promoted microbial growth and diversity and led to increases in abundance of Gram-positive dioxygenase genes, correlated with increased degradation of fluoranthene. This work contributes to knowledge in the broad area of biodegradation and also provides useful information for the design of future bioremediation strategies.

Science of The Total Environment, 2016

The accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food dema... more The 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 (N 2 O). The IPCC default emission factor (EF) for N 2 O from soils is 1% of the N applied, irrespective of its form. However, N 2 O 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 NH 3 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 N 2 O 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-(nbutyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N 2 O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N 2 O 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 N 2 O 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 N 2 O emissions, particularly in wet, temperate grassland.

. The management of agricultural soils during crop establishment can affect root development by c... more . The management of agricultural soils during crop establishment can affect root development by changes to soil structure. This paper assesses the influence of tillage depth (250 mm, 100 mm & zero) and traffic management (conventional tyre pressure, low tyre pressure & no traffic) on wheat root system architecture during winter wheat (Triticum aestivum L.) tillering and flowering growth stages (GS) on a long-term tillage trial site. The study revealed that zero-tillage systems increased crop yield through significantly greater root biomass, root length density and deeper seminal rooting analysed using X-ray Computed Tomography (CT). In general, conventional pressure trafficking had a significant negative influence on crop yield, root development, bulk density and total soil porosity of deep and shallow tillage conventional pressure systems compared no traffic zero and deep tillage systems. Visual improvements in soil structure under zero tillage may have improved crop rooting in zero tillage treatments through vertical pore fissures (biopores), enhancing water uptake during the crop flowering period. This study highlights the implications of soil structural damage on root system architecture created by compaction in crop production. The constricted root systems found in conventional pressure shallow tillage, zero and deep tillage trafficked regimes emphasizes the importance of using technology to improve soil management and reduce the trafficked areas of agricultural fields.

Agriculture, Ecosystems & Environment

Abstract The present study evaluated the impact of three nitrogen (N) fertiliser formulations, ap... more Abstract The present study evaluated the impact of three nitrogen (N) fertiliser formulations, applied at five N rates, on nitrous oxide (N2O) fluxes and annual direct N2O-N emission factors (EF) in temperate grassland. Closed static chambers were used to measure direct N2O fluxes at three geographically dispersed locations in Ireland over a two-year period, generating a total of 90 EFs across the six site-years and treatments. The three fertiliser formulations tested were calcium ammonium nitrate (CAN), urea, and urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) at 100, 200, 300, 400 and 500 kg N ha−1 yr−1. All treatments were applied in five equal split applications ranging from 20 to 100 kg N ha−1 split-1 over the growing season. The N2O-N EFs for CAN ranged from 0.39 − 4.68 with a mean of 1.62 (cv. 81 %), for urea from 0.04 – 1.7 with a mean of 0.46 (cv. 77 %) and for urea + NBPT from 0.18 – 1.7 with a mean of 0.60 (cv. 59 %). A significant positive relationship was found between the N rate and the annual N2O-N EFs in three (CAN), five (urea) and two (urea + NBPT) of six the site-years. For the remainder of the site-years EF was unaffected by N rate. These results indicate that fertiliser N choice and rate can be management factors that enable farmers to alter N2O losses in temperate grassland. Notably, the response of EF to increasing N rate was not consistent across the fertilisers, with the EF from urea being the most sensitive to the increasing N rate, urea + NBPT the least sensitive and CAN being intermediate. The accuracy of national greenhouse gas accounting could be improved by including N fertiliser formulation and its rate of application. Further research is also needed to understand the inconsistency in EF response to N rate across sites.

Energies

Microgeneration of electricity using solar photovoltaic (PV) systems is a sustainable form of ren... more Microgeneration of electricity using solar photovoltaic (PV) systems is a sustainable form of renewable energy, however uptake in Ireland remains very low. The aim of this study is to assess the potential of the community-based roof top solar PV microgeneration system to supply electricity to the grid, and to explore a crowd funding mechanism for community ownership of microgeneration projects. A modelled microgeneration project was developed: the electricity load profiles of 68 residential units were estimated; a community-based roof top solar PV system was designed; an electricity network model, based on a real network supplying a town and its surrounding areas, was created; and power flow analysis on the electrical network for system peak and minimum loads was carried out. The embodied energy, energy payback time, GHG payback time, carbon credits and financial cost relating to the proposed solar PV system were calculated. Different crowdfunding models were assessed. Results show ...

Soil Use and Management

Department of Agriculture, Environment and Rural Affairs in Northern Ireland, the Teagasc Walsh F... more Department of Agriculture, Environment and Rural Affairs in Northern Ireland, the Teagasc Walsh Fellowship Scheme

Soil Use and Management, 2015

Fertiliser nitrogen (N) contributes to ammonia (NH 3) emissions, which European Union member stat... more Fertiliser nitrogen (N) contributes to ammonia (NH 3) emissions, which European Union member states have committed to reduce. This study evaluated NH 3-N loss from a suite of N fertilisers over multiple applications, and on gaining insights into the temporal and seasonal patterns of NH 3-N loss from urea in Irish temperate grassland using wind tunnels. The fertilisers evaluated were: calcium ammonium nitrate (CAN), urea, and urea with the N stabilisers N-(n-butyl) thiophosphoric triamide (NBPT), dicyandiamide (DCD), DCD+NBPT, and a maleic and itaconic acid polymer (MIP). 200 (and 400 for urea only) kg N/ha/yr was applied in five equal applications over the growing season at two grassland sites (one for MIP). Mean NH 3-N losses from CAN were 85% lower than urea which had highly variable loss (range 45% points). The effect of DCD on NH 3 emissions was variable. MIP did not decrease loss but NBPT caused a 78.5% reduction, and when combined with DCD, a 74% reduction compared with urea alone. Mean spring and summer losses from urea were similar, although spring losses were more variable with both the lowest and highest loss levels. Maximum NH 3-N loss usually occurred on the second day after application. These data highlight the potential of stabilised urea to alter urea NH 3-N loss outcomes in temperate grassland, the need for caution when using season as a loss risk guide and that urea hydrolysis and NH 3-N loss in temperate grassland is rapid. Micrometeorological measurements focused specifically on urea are needed to determine absolute NH 3-N loss levels in Irish temperate grassland.

Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions ... more Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions in 2012, with 39% of these emissions arising from chemical/organic fertilizers in the form of nitrous oxide (N2O). Switching from calcium ammonium nitrate (CAN) to a urea based fertiliser limits the soil residence period of nitrate, the major substrate for denitrification loss in the N2O form. However, urea is susceptible to ammonia (NH3) volatilisation but this risk can be managed using urease inhibitors. The aim of this study was to evaluate the effect of switching from CAN to urea, urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (trade name Agrotain ®) and/or the nitrification inhibitor dicyandiamide (DCD on direct and indirect N2O emissions. The experiment is a two year study (commenced March 2013) at six permanent pasture sites located on the island of Ireland, at Johnstown Castle Co. Wexford, Moorepark Co. Cork and Hillsborough Co. Down, covering a range of soil ...

Energies

Data centres, though a necessary part of modern society, are being stigmatised for consuming vast... more Data centres, though a necessary part of modern society, are being stigmatised for consuming vast amounts of electricity for their operational and cooling needs. Due to Ireland’s reliance on fossil fuels to meet the increased energy demand of data centres, the data centres are contributing significantly to Ireland’s total carbon emissions. As much of this energy is expelled from data centres as waste heat energy, the potential for recycling some of this wasted heat energy was explored using environmentally friendly systems from recent publications. The recovered waste heat energy was applied in a vertical farming system, and the benefits of this waste heat to the vertical farm were analysed and quantified in two scenarios. Using conservative estimates, it was predicted that each vertical farm could be between 5–23% the size of the data centre and produce enough food to feed between 14–61 adults their daily calorie needs, and between 13–58 people their daily fresh produce requirement...

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Science of The Total Environment, 2016

Nitrogen

Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are... more Nitrogen (N) losses are a major environmental issue. Globally, crop N fertilizer applications are excessive, and N use efficiency (NUE) is low. N loss represents a significant economic loss to the farmer. NUE is difficult to quantify in real time because of the multiple chemical–biological–physical factors interacting. While there is much scientific understanding of N interactions in the plant–soil system, there is little formal expression of scientific knowledge in farm practice. The objective of this study was to clearly define the factors controlling NUE in wheat production, focusing on N inputs, flows, transformations, and outputs from the plant–soil system. A series of focus groups were conducted with professional agronomists and industry experts, and their technical information was considered alongside a structured literature review. To express this understanding, clear graphical representations are provided in the text. The analysis of the NUE processes revealed 16 management...

Journal of Biomedical Research & Environmental Sciences

Since 2010, solar Photovoltaic (PV) has been the single fastest growing power generation technolo... more Since 2010, solar Photovoltaic (PV) has been the single fastest growing power generation technology worldwide. However, given that the useful lifetime of a PV installation currently stands at 25 years and that current industry End-of-Life (EOL) management techniques, focus primarily on recycling and disposal, it has been estimated that by 2050, there will exist 78 million tonnes of hazardous solar PV waste. One potential solution that could aid in mitigating this impending environmental crisis, is determining whether or not the lifetime of commercial and residential solar PV installations can be elongated from the industry standard of 25 years to 50 years. Two novel solar PV ownership models, “The Cascading Tiered Commercial Ownership model” (CTCO) and “The Elongated Residential Ownership model” (ERO) have been created by projecting the technical outputs and economic Net Present Values (NPV) of a 60 kwp commercial and 4.8 kWp residential installation operated over a 50 as opposed to...

Geoderma, 2018

Biogeochemical models have the potential to provide insights into the key drivers of greenhouse g... more Biogeochemical models have the potential to provide insights into the key drivers of greenhouse gas (GHG) dynamics, and may be used in Tier 2 and 3 GHG emission reporting. Modelling nitrous oxide (N 2 O) emissions from agriculture, however, is still subject to large uncertainties. In the present study we analysed the performance of the three semi-mechanistic models, DailyDayCent (DayCent), DeNitrification-DeComposition (DNDC 9.4 and 9.5), and ECOSSE when simulating N 2 O fluxes from two different land uses (simulated grazing and spring barley) under a range of fertiliser types and application rates. Model performance was assessed using linear regression analysis, root mean square error (RMSE), and relative error. Monte Carlo analysis was carried out to assess the sensitivity of DayCent and ECOSSE to changes in the timing of management events. The results show high variability in model performance. The performance of each model was dependent on both site and treatment, with no model showing consistently good performance. When averaged across all sites and treatments DayCent simulations produced the lowest number of significant total and relative errors. When looking at the relationship between modelled and measured N 2 O fluxes, ECOSSE performed best with a significant relationship in 61.8% of all simulations and an average r 2 of 0.2. However, outputs from this model displayed the largest total and relative errors. Performance when simulating cumulative fluxes was generally poor. The Monte Carlo analysis showed that shifts in timing of management events by ± 7 days lead to annual N 2 O fluxes varying by 5.6 ± 7.6% and 2.8 ± 4.2% for grassland and cropland, respectively. However the impact of the timing of single events can lead to much larger responses in N 2 O emissions. The large variation in model performance suggests that further development and calibration is required before using models in GHG reporting.

Journal of Plant Nutrition, 1998

Urease inhibitors and nitrification inhibitors can reduce nitrogen (N) loss in agriculture soil. ... more Urease inhibitors and nitrification inhibitors can reduce nitrogen (N) loss in agriculture soil. However, the effect of inhibitors on soil N 2 O emissions under the drip irrigation system remains unclear. A pot and a field experiment with two inhibitors were conducted to explore how inhibitors regulate soil nitrogen transformation and N 2 O emissions. In the pot experiment, three treatments included control, urea, and urea + N-(n-butyl)thiophosphoric triamide (NBPT, urease inhibitor). In the field experiment, three treatments included control, urea, and urea + NBPT + 2-chloro-6-(trichloromethyl)pyridine (nitrapyrin, nitrification inhibitor). The urease inhibition rate in the treatment of urea + NBPT was 27.5% at the 14th day of incubation (pot experiment), and NH 4 +-N was significantly decreased by 37-64% compared with urea alone treatment. In the field experiment, the nitrification inhibition rate in the treatment of urea + NBPT + nitrapyrin was 47.7 and 63.9% on the 3rd day after fertilization at the wheat heading and filling stages, respectively. Compared to urea treatment, NO 3 −-N concentration in the double-inhibitor-added treatment was significantly decreased by 32 and 20% on the 5th day after fertilization at the heading and filling stages, respectively; N 2 O fluxes were also decreased by 30.9 and 33.3% at the two stages of wheat, respectively. In total, adding an inhibitor reduced N loss by 7.39 and 7.44% at the 14th and 35th day in the pot experiment and by 10.53 and 6.65% at the two growing stages of wheat in the field experiment, respectively. Path and correlation analysis showed that N 2 O emissions were significantly correlated with soil NO 3 − in both pot and field experiments.

Journal of Applied Microbiology, 2014

To investigate bacterial and fungal community structure during degradation of varying concentrati... more To investigate bacterial and fungal community structure during degradation of varying concentrations (0-5000 mg kg(-1) ) of the polycyclic aromatic hydrocarbon (PAH) fluoranthene in the presence or absence of tomato plants. Fluoranthene amended or unamended growing media, with or without a plant, were incubated in pots in a glasshouse for 30 days. Fluoranthene concentration was quantified using GC-FID, while bacterial and fungal community structure was investigated using trflp and arisa, respectively. The abundance of two ring hydroxylating dioxygenase genes was measured using qPCR. More fluoranthene was degraded in the presence of tomato plants at 500 and 5000 mg fluoranthene kg(-1) (P < 0·001), and it had a toxic effect on plant growth. Bacterial and fungal community composition in the rhizosphere was significantly different from that in nonrhizospheric and unplanted samples. The influence of fluoranthene on bacterial communities overcame that of the plant root such that community composition in rhizosphere and planted nonrhizospheric samples was broadly similar when fluoranthene was present. PAH-RHDα-GP genes were more abundant than PAH-RHDα-GN genes in all treatments. PAH-RHDα-GN abundance was unaffected by either PAH concentration or growing medium type, while the abundance of PAH-RHDα-GP was greatest in the rhizosphere. Plants promoted microbial growth and diversity and led to increases in abundance of Gram-positive dioxygenase genes, correlated with increased degradation of fluoranthene. This work contributes to knowledge in the broad area of biodegradation and also provides useful information for the design of future bioremediation strategies.

Science of The Total Environment, 2016

The accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food dema... more The 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 (N 2 O). The IPCC default emission factor (EF) for N 2 O from soils is 1% of the N applied, irrespective of its form. However, N 2 O 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 NH 3 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 N 2 O 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-(nbutyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N 2 O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N 2 O 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 N 2 O 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 N 2 O emissions, particularly in wet, temperate grassland.

. The management of agricultural soils during crop establishment can affect root development by c... more . The management of agricultural soils during crop establishment can affect root development by changes to soil structure. This paper assesses the influence of tillage depth (250 mm, 100 mm & zero) and traffic management (conventional tyre pressure, low tyre pressure & no traffic) on wheat root system architecture during winter wheat (Triticum aestivum L.) tillering and flowering growth stages (GS) on a long-term tillage trial site. The study revealed that zero-tillage systems increased crop yield through significantly greater root biomass, root length density and deeper seminal rooting analysed using X-ray Computed Tomography (CT). In general, conventional pressure trafficking had a significant negative influence on crop yield, root development, bulk density and total soil porosity of deep and shallow tillage conventional pressure systems compared no traffic zero and deep tillage systems. Visual improvements in soil structure under zero tillage may have improved crop rooting in zero tillage treatments through vertical pore fissures (biopores), enhancing water uptake during the crop flowering period. This study highlights the implications of soil structural damage on root system architecture created by compaction in crop production. The constricted root systems found in conventional pressure shallow tillage, zero and deep tillage trafficked regimes emphasizes the importance of using technology to improve soil management and reduce the trafficked areas of agricultural fields.

Agriculture, Ecosystems & Environment

Abstract The present study evaluated the impact of three nitrogen (N) fertiliser formulations, ap... more Abstract The present study evaluated the impact of three nitrogen (N) fertiliser formulations, applied at five N rates, on nitrous oxide (N2O) fluxes and annual direct N2O-N emission factors (EF) in temperate grassland. Closed static chambers were used to measure direct N2O fluxes at three geographically dispersed locations in Ireland over a two-year period, generating a total of 90 EFs across the six site-years and treatments. The three fertiliser formulations tested were calcium ammonium nitrate (CAN), urea, and urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) at 100, 200, 300, 400 and 500 kg N ha−1 yr−1. All treatments were applied in five equal split applications ranging from 20 to 100 kg N ha−1 split-1 over the growing season. The N2O-N EFs for CAN ranged from 0.39 − 4.68 with a mean of 1.62 (cv. 81 %), for urea from 0.04 – 1.7 with a mean of 0.46 (cv. 77 %) and for urea + NBPT from 0.18 – 1.7 with a mean of 0.60 (cv. 59 %). A significant positive relationship was found between the N rate and the annual N2O-N EFs in three (CAN), five (urea) and two (urea + NBPT) of six the site-years. For the remainder of the site-years EF was unaffected by N rate. These results indicate that fertiliser N choice and rate can be management factors that enable farmers to alter N2O losses in temperate grassland. Notably, the response of EF to increasing N rate was not consistent across the fertilisers, with the EF from urea being the most sensitive to the increasing N rate, urea + NBPT the least sensitive and CAN being intermediate. The accuracy of national greenhouse gas accounting could be improved by including N fertiliser formulation and its rate of application. Further research is also needed to understand the inconsistency in EF response to N rate across sites.

Energies

Microgeneration of electricity using solar photovoltaic (PV) systems is a sustainable form of ren... more Microgeneration of electricity using solar photovoltaic (PV) systems is a sustainable form of renewable energy, however uptake in Ireland remains very low. The aim of this study is to assess the potential of the community-based roof top solar PV microgeneration system to supply electricity to the grid, and to explore a crowd funding mechanism for community ownership of microgeneration projects. A modelled microgeneration project was developed: the electricity load profiles of 68 residential units were estimated; a community-based roof top solar PV system was designed; an electricity network model, based on a real network supplying a town and its surrounding areas, was created; and power flow analysis on the electrical network for system peak and minimum loads was carried out. The embodied energy, energy payback time, GHG payback time, carbon credits and financial cost relating to the proposed solar PV system were calculated. Different crowdfunding models were assessed. Results show ...

Soil Use and Management

Department of Agriculture, Environment and Rural Affairs in Northern Ireland, the Teagasc Walsh F... more Department of Agriculture, Environment and Rural Affairs in Northern Ireland, the Teagasc Walsh Fellowship Scheme

Soil Use and Management, 2015

Fertiliser nitrogen (N) contributes to ammonia (NH 3) emissions, which European Union member stat... more Fertiliser nitrogen (N) contributes to ammonia (NH 3) emissions, which European Union member states have committed to reduce. This study evaluated NH 3-N loss from a suite of N fertilisers over multiple applications, and on gaining insights into the temporal and seasonal patterns of NH 3-N loss from urea in Irish temperate grassland using wind tunnels. The fertilisers evaluated were: calcium ammonium nitrate (CAN), urea, and urea with the N stabilisers N-(n-butyl) thiophosphoric triamide (NBPT), dicyandiamide (DCD), DCD+NBPT, and a maleic and itaconic acid polymer (MIP). 200 (and 400 for urea only) kg N/ha/yr was applied in five equal applications over the growing season at two grassland sites (one for MIP). Mean NH 3-N losses from CAN were 85% lower than urea which had highly variable loss (range 45% points). The effect of DCD on NH 3 emissions was variable. MIP did not decrease loss but NBPT caused a 78.5% reduction, and when combined with DCD, a 74% reduction compared with urea alone. Mean spring and summer losses from urea were similar, although spring losses were more variable with both the lowest and highest loss levels. Maximum NH 3-N loss usually occurred on the second day after application. These data highlight the potential of stabilised urea to alter urea NH 3-N loss outcomes in temperate grassland, the need for caution when using season as a loss risk guide and that urea hydrolysis and NH 3-N loss in temperate grassland is rapid. Micrometeorological measurements focused specifically on urea are needed to determine absolute NH 3-N loss levels in Irish temperate grassland.

Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions ... more Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions in 2012, with 39% of these emissions arising from chemical/organic fertilizers in the form of nitrous oxide (N2O). Switching from calcium ammonium nitrate (CAN) to a urea based fertiliser limits the soil residence period of nitrate, the major substrate for denitrification loss in the N2O form. However, urea is susceptible to ammonia (NH3) volatilisation but this risk can be managed using urease inhibitors. The aim of this study was to evaluate the effect of switching from CAN to urea, urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (trade name Agrotain ®) and/or the nitrification inhibitor dicyandiamide (DCD on direct and indirect N2O emissions. The experiment is a two year study (commenced March 2013) at six permanent pasture sites located on the island of Ireland, at Johnstown Castle Co. Wexford, Moorepark Co. Cork and Hillsborough Co. Down, covering a range of soil ...