The effects of nutrient losses from agriculture on ground and surface water quality: the position of science in developing indicators for regulation

Abstract The magnitude of current nutrient losses from agriculture to ground and surface water calls for effective environmental policy, including the use of regulation. Nutrient loss is experienced in many countries despite differences in the organisation and intensity of agricultural production. However, at present there is no internationally agreed practice to assess the effectiveness of different kinds of regulatory practice and compliance level, or to make effective comparisons. There is a wide variety of indicators available for this purpose, ranging from livestock density and input–ouput balances to nutrient concentrations in soil and water. This paper explores the effectiveness and efficiency of the different indicators, both in terms of achieving a single objective and a comprehensive set of objectives and evaluates how responsive and attributable these indicators are to changes in farm management. Each indicator appears to have its own pros and cons. Unfortunately, there does not seem to be a single indicator that is effective, comprehensive, efficient, responsive and attributable at the same time. Scientifically, there are valid reasons to develop indicators that account for specific regional conditions and to accept the use of varying threshold values within them. Administratively complex indicators and/or strict threshold values appear inevitable wherever intensive production is the dominant form of land use amidst vulnerable local environments. However, at both a national and international level this differentiation of indicators and thresholds may conflict with the desire to treat individual farmers equally and to minimise their administrative burden. The paper concludes with a review of the issues raised in international harmonisation of nutrient loss indicators and threshold values.

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