Using the nutrient transfer continuum concept to evaluate the European Union Nitrates Directive National Action Programme

Agricultural catchments are where farm and landscape management interact with policy and science; especially with regard to the implementation and evaluation of agri-environmental regulation. The Nitrates Directive constrains nitrogen and phosphorus use and management on agricultural land across all EU member states and is one of the programmes of measures to mitigate eutrophication of water resources under the Water Framework Directive. All policies require a robust evaluation tool and for the potential diffuse transfer of nutrients from land to water, the nutrient transfer continuum concept is applied here as an example framework in small (6-30 km(2)) catchments. The experimental design, methods and some early results are presented: auditing nutrient sources to established levels of compliance is the first stage and considers nutrient use and soil status. Studying pathways provides an understanding of linkages between the land sources and delivery in catchment rivers. This delivery is generally associated with episodic, high magnitude transfers and may not necessarily be the only or even primary ecological impact in rivers. Critiquing existing delivery/impact metrics and defining appropriate standards for identifying trajectories associated with diffuse nutrient transfer will be important in ensuring that agri-environmental policies are given a fair and thorough evaluation over a suitable time period. (C) 2011 Elsevier Ltd. All rights reserved.