Description succincte
(Anglais)
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In many regions worldwide, diffuse P losses from agriculture are the main cause of eutrophication of surface waters. Studies in different countries indicate that those losses originate from a small portion of a given catchment only. Accordingly, mitigation could be achieved by adapting the land management on these critical areas to minimize P losses. It is expected that such site-specific measures are much more cost-effective compared to options applied to all farming land. The suggested project aims at improving the predictive capabilities of an existing modelling tool delineating critical source areas. It will test, extend and improve this distributed model for P losses. The model focuses mainly on transport of dissolved P from intensively used grassland soils in small agricultural catchments. It will be tested by applying it to new catchments. The test areas are located within the watershed of lake Baldegg, which is one of the critical lakes in Switzerland that need further P reduction to achieve a good ecological status. Special emphasis will be placed on the uncertainty related to the spatial predictions. Such knowledge is crucial for the implementation of the model in practice. The existing model will be extended such as to include the P loss dynamic after manure applications (incidental P losses). In order to test and parameterize the according model module field experiments will be carried out to study the influence of manure on runoff behaviour and P concentrations from grassland soils. Finally, the model will be used to evaluate possible management strategies that will be developed in collaboration with local administrators. Scenario calculations using the extended model will assess their reduction potential.
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Partenaires et organisations internationales
(Anglais)
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AT, BE, CH, CZ, DE, DK, EE, ES, FI, FR, GR, HU, IE, IL, IT, LT, LU, LV, NL, NO, PL, PT, RO, SE, SI, SK, UK
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Résumé des résultats (Abstract)
(Anglais)
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In many regions, diffuse P losses from agriculture are the main cause for eutrophication of surface waters. Studies in different countries indicate that these losses originate from a small portion of a given catchment only. The localisation of such critical source areas is a prerequisite for the evaluation of efficient and cost-effective mitigation options. Within the framework of COST Action 869 on 'Mitigation options for nutrient reduction in surface water and groundwater' we are working on a project that aims to improve an existing model to predict and delineate critical source areas for P-losses from agricultural land. The model focuses on transport of dissolved P from intensively used grassland soils in small agricultural catchments. In general, the model results were promising but several questions arose regarding the role of incidental P losses (IPL). To investigate those questions sprinkling experiments were carried out in summer 2008. The experimental sites were located within small watersheds discharging into lake Baldegg, a lake in central Switzerland with serious eutrophication problems due to P inputs from agriculture. Based on these experiments the model will be extended in particular to predict P runoff after manure applications (incidental P losses). In order to test the model spatial measurements are planned within the same small watersheds. Special emphasis will be placed on the uncertainty related to the spatial predictions. The model is designed to evaluate possible management strategies in collaboration with local agricultural consultants and cantonal authorities. Scenario calculations will be performed to assess their potential to reduce P loads in Lake Baldegg.
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