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ToolsBateman, Ian J., Deflandre-Vlandas, Amelle, Fezzi, Carlo, Hadley, David, Hutchins, Michael, Lovett, Andrew, Posen, Paulette and Rigby, Dan (2008) WFD related agricultural nitrate and phosphate leaching reduction options: Cost estimates derived from farm level survey data & A cost-effectiveness assessment for the Derwent catchment. Working Paper - Centre for Social and Economic Research on the Global Environment (1). pp. 1-62. ISSN 0967-8875
Full text not available from this repository.Abstract
The Water Framework Directive (WFD) (European Commission, 2000) represents a fundamental change in the management of water quality in Europe. Amongst many fundamental changes to previous practice, the Directive moves the emphasis of policy from assessments of the chemical composition of waterways towards their biological condition. Specifically, it requires an improvement of all European waters to a 'good ecological status' by 2015. This in turn requires a reduction of diffuse pollution, the primary source of which is agriculture. Clearly, the benefits of reduced nitrate concentrations in rivers and lakes are likely to come at some cost to farms. This study is an assessment of various policy options proposed to Defra to achieve the standards required by the WFD. Specifically, we consider (a) reducing inorganic fertiliser applications, (b) conversion of arable land to un-grazed grassland, (c) reducing livestock stocking rates (d) reducing livestock dietary N and P intakes. For each measure, we assess both the costs for agriculture (in terms of reduction in activity gross margin (GM) and hence farm gross margin (FGM)) and the benefits in terms of improvement in water quality, measured in N and P concentration in rivers. Section 1 presents an economic analysis of the impacts of the various measures on UK farming systems. Changes in farm gross margins are estimated using a panel dataset of roughly 2400 farms collected by the Farm Business Survey (FBS). In contrast to previous (principally linear programming) analyses, which have focused upon mean responses at stylised farms, our approach allows analysis of the range of impacts across a wide variety of real-world farms and farm types. This wealth of data encompasses the complex agroclimatic, environmental and farm system variation that characterizes the diversity of agriculture across England and Wales. Our analysis reveals considerable variability in the economic impact of the measures considered. This diversity varies across both policy measure and the individual characteristics of the farm. Contrasting these cost estimates with existing analyses of the nitrate leaching effect of different measures suggests that, while there are clear differences in the cost-effectiveness of a policy within a farming sector, targeting policies to specific farm types can achieve superior outcomes. In particular, targeting arable systems appears a more cost effective approach to reducing nitrate leaching than applying the same measure to all farm types. This result is explained by two factors: higher GM/ha and a more responsive relationship between revenue and inputs (particularly fertilizer) for livestock (in particular dairy) farms. Regarding phosphate, the most efficient policy is reducing stocking rates in beef and sheep farms, followed again by the measures targeting arable systems. Nevertheless, the variability in impacts demonstrated by this analysis shows how WFD related measures can result in substantial reductions in GMs in a significant number of enterprises. Such variation is somewhat hidden within stylized "average" farm studies. We extend our analysis to develop regression models of the responsiveness of FGM to each policy option. Equipped with these statistical relationships between farm characteristics and potential WFD measure impacts, one can predict the likely FGM changes in a specific area if one knows the land use activities carried on in that area. We conclude Section 1 with a consideration of the limitations of this analysis. We emphasise that this approach does not include any behavioural element but implements the effects of the various policies in a rather mechanical fashion. For example, switches between different land uses and activities (apart from the arable land conversion) in response to the measures are not considered. Furthermore, only gross margins are analysed, thereby providing no indication about profits and long run investment costs. Considering nitrate, prior cost-effectiveness work has focussed upon rates of leaching from fields. A limitation of such approaches is that they ignore the in-stream processes which determine the ultimate ecological impact of nitrate pollution which is the focus of the WFD. This limitation is relaxed in Section 2 of this report, which uses an integrated hydrological model to estimate the changes in water quality arising from of a range of measures considered previously. The focus is on the Yorkshire Derwent catchment. The nitrate flow modelling involves the integration of two hydrological models: CASCADE (CAtchment SCAle DElivery), a diffuse pollution model, and QUESTOR (QUality Evaluation and Simulation TOol for River-systems) an in-stream water quality model. This allows us to obtain estimates of the nitrate concentrations into the river system, (rather than absolute nitrate load deriving from diffuse pollution) which, as mentioned, has direct bearing upon ecological status; the primary objective of the WFD. We show that only drastic changes in land use (e.g. from arable to low intensity grassland systems) can result in significant reductions in levels of nitrate-N leaching in the catchment under analysis. Thus, for example, feasible reductions in fertiliser levels are insufficient to generate such changes. Furthermore, levels of nitrate leaching are very sensitive to short-term rainfall patterns, particularly when levels of leachable nitrate-N in the soil are high following crop harvest. In addition, spatial targeting of measures in parts of the catchment has an impact on the water quality. Nitrate-N content at the catchment outlet is sensitive to where mitigation options are targeted. The measures under consideration appear most effective if targeted throughout the catchment; importantly, including lower catchment areas close to downstream reaches where intensive agriculture is more prevalent than elsewhere. In Section 3, the modelling approaches outlined in the two previous sections are used to evaluate the policy measures in the Yorkshire Derwent catchment. The economic (Section 1) and the hydrological (Section 2) modelling are founded on coherent assumptions thereby providing an integrated framework to evaluate various WFD policy implementations. Our case study area has been chosen for its heterogeneity (the northern part is dominated by grazing livestock whereas the south is mainly devoted to crop cultivation) and for the high fraction of agricultural and natural areas within it (urban and suburban areas constitute less than 8% of the total case study area). For this reason, the nitrate in rivers within the catchment is mainly from diffuse, agricultural pollution sources. Furthermore, the catchment contains areas of special interest in the context of the Catchment Sensitive Farming Programme. Our findings suggest that achieving considerable improvements in the water quality within the Derwent would require substantial land use changes, including switching a significant portion of arable cropping to un-grazed grassland. Indeed, this seems to be the most efficient measure, being roughly three times more efficient than the other two policy options considered. Furthermore, particularly high water quality standards can be achieved in the areas deemed of special interest if the land conversion is targeted to those specific sub-catchments, providing, at the same time, important nitrate reductions at the catchment outlet. However, these improvements in water quality will come at a significant cost for the local rural economy. For example, reducing N concentration at the catchment outlet by nearly 20% (switching arable land to un-grazed grassland) would reduce aggregated Derwent's FGM by roughly £5.5 million.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | assessment method,catchment,chemical composition,concentration (composition),cost-benefit analysis,economic analysis,environmental modeling,leaching,nitrate,reduction,regression analysis,water quality,global and planetary change,geography, planning and development,aerospace engineering,management, monitoring, policy and law,earth and planetary sciences(all) ,/dk/atira/pure/subjectarea/asjc/2300/2306 |
| UEA Research Groups: | Faculty of Science > Research Centres > Centre for Social and Economic Research on the Global Environment (CSERGE) |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 03 Dec 2025 11:30 |
| Last Modified: | 03 Dec 2025 12:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/101219 |
| DOI: |
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