title: Paddock scale nitrous oxide emissions from intensively grazed pasture: Quantification and mitigation

authors: Wecking, Anne Roswitha

subjects: Greenhouse gas

abstract: Agricultural soils are the main contributor to global emissions of the potent greenhouse gas nitrous oxide (N₂O) to the atmosphere. Nitrous oxide can absorb and transform radiative energy emitted from the sun to earth into heat. The ability of N₂O to absorb energy is part of the greenhouse effect and naturally contributes to habitable temperature conditions for life on earth. Atmospheric concentrations of N₂O have never before increased as rapidly as observed since the onset of industrialisation. High N₂O concentrations enhance the greenhouse effect and, at present, add to a warming atmosphere and a changing climate. A major pathway for N₂O production is from soils that receive large surpluses of reactive nitrogen, e.g., in the form of animal excreta or fertiliser. Once available in the soil, microbes can access and transform this nitrogen into different compounds: N₂O, for example. The current contribution of agricultural soils to global N₂O emissions is about 60% but higher in New Zealand, where soils are responsible for 94% of national N₂O emissions. However, robust quantifications are not straightforward and challenging for science to overcome. This thesis is sited at the interface of this challenge and aimed at measuring the exchange of N₂O over an intensively grazed dairy pasture in New Zealand. The core of the work was based on eddy covariance (EC), a technique that allows measuring the N₂O exchange between the soil and the atmosphere at ten times per second. Since EC measurements of N₂O over dairy grazed land are rare, main objectives of this work were: to 1) compare EC to traditional measurement approaches, i.e. static chambers, 2) quantify annual N₂O emission budgets and 3) determine the effect of farm management including pasture renewal on N₂O emissions. The findings of this thesis show that EC provided a realistic picture of the N₂O exchange at paddock scales. This means EC data identified cattle grazing, land history, farm management, soil moisture and temperature as the main factors controlling N₂O exchange throughout the year. Interestingly, using one EC system for measurements across adjacent but differently managed paddocks also allowed to compare the effect of different pasture management scenarios on N₂O emissions. This will help researchers to test different mitigation options more easily in the future, ideally, to reduce N₂O emissions and avoid further atmospheric warming. This thesis advances our understanding of the N₂O exchange process from intensively grazed land as well as it shows how limited this knowledge still is. Micrometeorological N₂O flux measurements will have to be used more frequently in the future to provide researchers with answers in the face of a rapidly changing climate on earth.

text: Paddock scale nitrous oxide emissions from intensively grazed pasture: Quantification and mitigation Agricultural soils are the main contributor to global emissions of the potent greenhouse gas nitrous oxide (N₂O) to the atmosphere. Nitrous oxide can absorb and transform radiative energy emitted from the sun to earth into heat. The ability of N₂O to absorb energy is part of the greenhouse effect and naturally contributes to habitable temperature conditions for life on earth. Atmospheric concentrations of N₂O have never before increased as rapidly as observed since the onset of industrialisation. High N₂O concentrations enhance the greenhouse effect and, at present, add to a warming atmosphere and a changing climate. A major pathway for N₂O production is from soils that receive large surpluses of reactive nitrogen, e.g., in the form of animal excreta or fertiliser. Once available in the soil, microbes can access and transform this nitrogen into different compounds: N₂O, for example. The current contribution of agricultural soils to global N₂O emissions is about 60% but higher in New Zealand, where soils are responsible for 94% of national N₂O emissions. However, robust quantifications are not straightforward and challenging for science to overcome. This thesis is sited at the interface of this challenge and aimed at measuring the exchange of N₂O over an intensively grazed dairy pasture in New Zealand. The core of the work was based on eddy covariance (EC), a technique that allows measuring the N₂O exchange between the soil and the atmosphere at ten times per second. Since EC measurements of N₂O over dairy grazed land are rare, main objectives of this work were: to 1) compare EC to traditional measurement approaches, i.e. static chambers, 2) quantify annual N₂O emission budgets and 3) determine the effect of farm management including pasture renewal on N₂O emissions. The findings of this thesis show that EC provided a realistic picture of the N₂O exchange at paddock scales. This means EC data identified cattle grazing, land history, farm management, soil moisture and temperature as the main factors controlling N₂O exchange throughout the year. Interestingly, using one EC system for measurements across adjacent but differently managed paddocks also allowed to compare the effect of different pasture management scenarios on N₂O emissions. This will help researchers to test different mitigation options more easily in the future, ideally, to reduce N₂O emissions and avoid further atmospheric warming. This thesis advances our understanding of the N₂O exchange process from intensively grazed land as well as it shows how limited this knowledge still is. Micrometeorological N₂O flux measurements will have to be used more frequently in the future to provide researchers with answers in the face of a rapidly changing climate on earth.

year: 2021

title: A theory of change driven approach to evaluating a multi-agency stalking intervention programme

authors: Belur, Jyoti

subjects: multi-agency partnership

abstract: Purpose: Multi-agency initiatives as a response to complex crimes, such as stalking, pose conceptual and operational challenges for practitioners and evaluators. This study addresses these challenges, by combining a theory of change driven approach with the realist-inspired EMMIE evaluation framework to present findings from a pilot multi agency stalking intervention partnership in England and Wales. Methods: The study uses a mixed methods approach based on analysis of police data and semi-structured interviews with stakeholders to present a process and effect evaluation of a complex social intervention. Results: Findings based on a small sample and limited follow up period show nonsignificant results in terms of reducing the harmful effects of stalking, but which are encouragingly in the right direction. The case study demonstrates the importance of a theory driven approach to multi-agency evaluation and identifies essential factors necessary for ensuring implementation success. Conclusions: A theory of change driven approach and an EMMIE-inspired evaluation can help identify whether interventions work, how they work, for whom they work, and under what conditions. It demonstrates the importance of data collection and provision for long term evaluation plans, especially for complex social interventions. The paper makes a significant methodological and empirical contribution to evaluation literature.

text: A theory of change driven approach to evaluating a multi-agency stalking intervention programme Purpose: Multi-agency initiatives as a response to complex crimes, such as stalking, pose conceptual and operational challenges for practitioners and evaluators. This study addresses these challenges, by combining a theory of change driven approach with the realist-inspired EMMIE evaluation framework to present findings from a pilot multi agency stalking intervention partnership in England and Wales. Methods: The study uses a mixed methods approach based on analysis of police data and semi-structured interviews with stakeholders to present a process and effect evaluation of a complex social intervention. Results: Findings based on a small sample and limited follow up period show nonsignificant results in terms of reducing the harmful effects of stalking, but which are encouragingly in the right direction. The case study demonstrates the importance of a theory driven approach to multi-agency evaluation and identifies essential factors necessary for ensuring implementation success. Conclusions: A theory of change driven approach and an EMMIE-inspired evaluation can help identify whether interventions work, how they work, for whom they work, and under what conditions. It demonstrates the importance of data collection and provision for long term evaluation plans, especially for complex social interventions. The paper makes a significant methodological and empirical contribution to evaluation literature.

year: 2024

title: How differing methods of ascribing ethnicity and socio-economic status affect risk estimates for hospitalisation with infectious disease

authors: Hobbs, Mark R.

subjects: Ethnicity/race

abstract: Significant ethnic and socio-economic disparities exist in infectious diseases (IDs) rates in New Zealand, so accurate measures of these characteristics are required. This study compared methods of ascribing ethnicity and socio-economic status. Children in the Growing Up in New Zealand longitudinal cohort were ascribed to self-prioritised, total response and single-combined ethnic groups. Socio-economic status was measured using household income, and both census-derived and survey-derived deprivation indices. Rates of ID hospitalisation were compared using linked administrative data. Self-prioritised ethnicity was simplest to use. Total response accounted for mixed ethnicity and allowed overlap between groups. Single combined ethnicity required aggregation of small groups to maintain power but offered greater detail. Regardless of the method used, Māori and Pacific children, and children in the most socio-economically deprived households had a greater risk of ID hospitalisation. Risk differences between self-prioritised and total response methods were not significant for Māori and Pacific children but single-combined ethnicity revealed a diversity of risk within these groups. Household income was affected by non-random missing data. The census derived deprivation index offered a high level of completeness with some risk of multicollinearity and concerns regarding the ecological fallacy. The survey-derived index required extra questions but was acceptable to participants and provided individualised data. Based on these results, the use of single-combined ethnicity and an individualised survey-derived index of deprivation are recommended where sample size and data structure allow it.

text: How differing methods of ascribing ethnicity and socio-economic status affect risk estimates for hospitalisation with infectious disease Significant ethnic and socio-economic disparities exist in infectious diseases (IDs) rates in New Zealand, so accurate measures of these characteristics are required. This study compared methods of ascribing ethnicity and socio-economic status. Children in the Growing Up in New Zealand longitudinal cohort were ascribed to self-prioritised, total response and single-combined ethnic groups. Socio-economic status was measured using household income, and both census-derived and survey-derived deprivation indices. Rates of ID hospitalisation were compared using linked administrative data. Self-prioritised ethnicity was simplest to use. Total response accounted for mixed ethnicity and allowed overlap between groups. Single combined ethnicity required aggregation of small groups to maintain power but offered greater detail. Regardless of the method used, Māori and Pacific children, and children in the most socio-economically deprived households had a greater risk of ID hospitalisation. Risk differences between self-prioritised and total response methods were not significant for Māori and Pacific children but single-combined ethnicity revealed a diversity of risk within these groups. Household income was affected by non-random missing data. The census derived deprivation index offered a high level of completeness with some risk of multicollinearity and concerns regarding the ecological fallacy. The survey-derived index required extra questions but was acceptable to participants and provided individualised data. Based on these results, the use of single-combined ethnicity and an individualised survey-derived index of deprivation are recommended where sample size and data structure allow it.

year: 2019