9 results for Pannell, David J.

  • Agricultural land management strategies to reduce phosphorus loads in the Gippsland Lakes, Australia

    Roberts, Anna M.; Pannell, David J.; Doole, Graeme J.; Vigiak, Olga (2012)

    Journal article
    University of Waikato

    A target to reduce phosphorus flows into the Gippsland Lakes in south-eastern Australia by 40% in order to improve water quality has previously been established by stakeholders. This target, like many others worldwide, has been set mostly on the basis of environmental concerns, with limited consideration of issues such as technical feasibility, socio-economic constraints, political factors and associated costs and benefits. An integrated analysis at the catchment scale is undertaken to assess the agricultural land management changes required to achieve this target, and to evaluate the cost-effectiveness of these changes. Based on assumptions used, it appears technically feasible to achieve a 40% reduction in P load entering the Lakes. However, the least-costly way of doing so would require around A$1 billion over 25 years, a dramatic increase in the current levels of funding provided for management. Results of a sensitivity analysis indicate that there is little or no chance of investment in a 40% reduction being cost-effective. On the other hand, a 20% P reduction could be achieved at much lower cost: around $80 million over 25 years and requiring more modest land-management changes. Reliance on voluntary adoption of ‘Current Recommended Practices’ is unlikely to deliver changes in management practices at the scale required to have sufficient environmental impacts. Enforcement of existing regulations for the dairy industry would be amongst the most cost-effective management strategies. The major implications of this work for agriculturally induced diffuse-source pollution include the need for feedback between goal setting and program costs, and consideration of factors such as the levels of landholder adoption of new practices that are required and the feasibility of achieving those adoption levels. Costs, landholder adoption of new practices and socio-political risks appear neglected in the formulation of many water quality programs. The study provides a demonstration of an approach to integrated multidisciplinary research addressing complex environmental problems with multiple decision makers, multiple stakeholders, and high uncertainty. On the evidence of experience in this study, the approach deserves consideration in other contexts.

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  • Evaluating environmental policies under uncertainty through application of robust nonlinear programming

    Doole, Graeme J.; Pannell, David J. (2011)

    Journal article
    University of Waikato

    Environmental policy evaluation is characterised by a paucity of information. The novel technique of robust mathematical programming is introduced as a means to proactively account for this uncertainty in policy analysis. The procedure allows identification of expected bounds on the range of abatement costs associated with environmental policy. It also has the advantage of not limiting conclusions to realisations of specific point estimates or probability distributions. Empirical insights are provided in an application to a New Zealand inland lake threatened by nitrate pollution from dairy farming. Overall, this novel framework is demonstrated to have several key advantages, including explicit treatment of severe uncertainty, capacity to bound the range of expected abatement costs accruing to a given policy instrument, and the opportunity to identify robust plans that are immune to parametric variation.

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  • Economic implications of herbicide resistance and high labour costs for management of annual barnyardgrass (Echinochloa crus-galli) in Philippine rice farming systems

    Beltran, Jesusa C.; Pannell, David J.; Doole, Graeme J. (2010)

    Journal article
    University of Waikato

    Implications of increasing labour costs and the development of herbicide resistance for profitable weed management in Philippine rice farming systems are investigated. The study employs RIMPhil (Resistance and Integrated Management in the Philippines), a bioeconomic simulation model developed to provide a comprehensive assessment of integrated weed management programmes for the control of annual barnyardgrass (Echinochloa crus-galli) in rice crops. Results indicate that herbicide application will become increasingly economically attractive, relative to manual weeding, as labour cost increases. This is important since urban migration in the Philippines continues to increase the scarcity of rural labour. Results also show that the onset of herbicide resistance results in substantial losses in farm profit. It is worthwhile for farmers to take management actions to prevent or delay the onset of herbicide resistance, provided that these changes are effective and not too costly. The study highlights the complexity of decision making about integrated weed management on rice farms in the Philippines.

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  • Cost-effective strategies to mitigate multiple pollutants in an agricultural catchment in North Central Victoria, Australia

    Doole, Graeme J.; Vigiak, Olga; Pannell, David J.; Roberts, Anna M. (2013)

    Journal article
    University of Waikato

    Strategies to reduce phosphorus and sediment yields are identified for two Australian catchments using a nonlinear optimisation model. This provides novel insight into the cost-effective management of dual pollutants of water courses in Australia. A strong degree of complementarity between the two pollutants is highlighted, given the adsorption of phosphorus to sediment that augments the value of gully and streambank management for mitigation. However, the relationship between the two pollutants is asymmetric. A 30 per cent reduction in phosphorus yield achieves a 75 per cent reduction in sediment yield in one catchment, while a 30 per cent reduction in sediment yield achieves only a 12 per cent reduction in phosphorus yield. Sediment abatement costs are low given the efficiency of gully and streambank management. A 30 per cent phosphorus reduction lowers profit by 3–7 per cent, while a 30 per cent sediment reduction lowers profit by around 1 per cent. Land-use optimisation requires spatial heterogeneity in land-use and gully/streambank management responses. Overall, this research demonstrates the need to determine whether one pollutant is more important than another, while recognising the potential that mitigation practices possess for the reduction of multiple emissions during their evaluation.

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  • Framework for evaluating management interventions for water-quality improvement across multiple agents

    Doole, Graeme J.; Ramilan, Thiagarajah; Pannell, David J. (2011)

    Journal article
    University of Waikato

    It is difficult to accurately predict the impacts of policies for control of nonpoint-source pollution because analytical frameworks incorporating agent heterogeneity are rare. This paper overcomes this limitation through describing a new framework in which the behaviour of individual firms is explicitly represented by large, complex models calibrated to baseline information. Disaggregation allows the simulation of policies that require uniform reductions in pollutant load or those that allow different rates of abatement between firms to achieve a given nutrient target at least cost, as with the trading of pollution entitlements. The reduction of nitrate leaching from intensive dairy production in a catchment of the Waikato River in New Zealand is used as an illustrative application. It is highlighted that satisfaction of water-quality standards will incur substantial costs within this region. Overall, the framework is notable for its integration of multiple modelling techniques from diverse disciplines and its focus on the behaviour of individual agents. Moreover, it can easily be applied elsewhere where sufficient information is available.

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  • Empirical evaluation of nonpoint pollution policies under agent heterogeneity: regulating intensive dairy production in the Waikato region of New Zealand

    Doole, Graeme J.; Pannell, David J. (2011)

    Journal article
    University of Waikato

    Models used for policy evaluation rarely consider firm heterogeneity, despite its importance for instrument design. This study considers agent heterogeneity explicitly in the evaluation of policies for nonpoint pollution control through the integration of decomposition and calibration procedures for programming models. The application concerns the regulation of nitrate leaching from intensive dairy production in the Waikato region of New Zealand. Failing to represent firm heterogeneity leads to widely different estimates of mitigation costs, relative to where heterogeneity is considered. Variation in baseline emissions and the slopes of abatement cost curves between firms renders a differentiated policy less costly than a uniform standard. However, the relative values of these policies are not broadly different, as firms required to do the most abatement – intensive farms with large baseline pollutant loads – can do so more cheaply, on average.

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  • A bioeconomic model for analysis of integrated weed management strategies for annual barnyardgrass (Echinochloa crus-galli complex) in Philippine rice farming systems

    Beltran, Jesusa C.; Pannell, David J.; Doole, Graeme J.; White, Benedict (2012-10)

    Journal article
    University of Waikato

    This paper describes a dynamic simulation model that allows for comprehensive assessment of integrated weed management programmes for the control of annual barnyardgrass (Echinochloa crus-galli complex) in Philippine rice farming systems. The main outputs of the model include weed seed and plant densities and seasonal and annualised profit over the simulated planning horizon. Results broadly indicate that a mixture of chemical and non-chemical treatments provides good weed control in rice crops, and maximises long-term profit for systems where the main weed is annual barnyardgrass. However, the performance of this strategy is heavily influenced by crop establishment method and labour cost. At current labour cost and low weed density, the regular use of manual weeding is the most valuable primary form of weed control in rice farming systems, relative to herbicide application. Herbicide application becomes more profitable than manual weeding when labour costs increase or the population of barnyardgrass plants is not maintained at its optimal level. These results illustrate the value of the model for guiding the efficient control of annual barnyardgrass in rice crops in the Philippines.

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  • Determinants of herbicide use in rice production in the Philippines

    Beltran, Jesusa C.; White, Benedict; Burton, Michael; Doole, Graeme J.; Pannell, David J. (2013)

    Journal article
    University of Waikato

    This study identifies farm-specific and market factors affecting the adoption of herbicides and the level of herbicide use by rice farmers in the Philippines. This requires the application of a modified version of Heckman's two-step method to estimate a random-effects double-hurdle model for unbalanced panel data. The age of the farmer, household size, and irrigation use are significant determinants of the decision of farmers to adopt herbicides as an alternative to manual weeding, while economic variables such as the price of herbicides, total income, and access to credit determine the level of herbicide use. Determinants of both adoption and level are land ownership, farm area, and the method of crop establishment. These results are potentially relevant when designing policies to reduce excessive herbicide use or to encourage the adoption of alternative weed control methods such as integrated weed management.

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  • A process for the development and application of simulation models in applied economics

    Doole, Graeme J.; Pannell, David J. (2013)

    Journal article
    University of Waikato

    Simulation models are widely used in applied economics to improve understanding of how a system could behave under different conditions. However, the potential degree to which such models can influence decision making depends on their ability to provide an adequate description of the important elements of a given problem. A systematic and robust procedure for the development and application of such models in agricultural, ecological, environmental and natural resource economics is presented. This process is based on the authors' experience across a broad range of model types and applications and extensive literature review. The practical impact of simulation models is argued to be greater where stakeholders and technical experts are consulted extensively throughout the modelling process.

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