Nitrogen: the essential public enemy.
In this paper, we discuss the impacts in the UK and give examples of the steps that are being taken by the Department for Environment, Food and Rural Affairs (Defra) to tackle these problems. Over 70% of the UK land area is farmland. The farmed environment is composed of a wide range of semi-natural habitats including heather moorland, chalk downland, wet grasslands farm woodlands and hedgerows. As a result, much of the UK's cherished biodiversity is an integral part of agriculture and therefore vulnerable to changes in farming practices. Defra's overall goal is to build a sustainable future for the UK. With regard to nitrogen pollution, this involves finding ways of continuing to meet our food and energy requirements whilst causing little or no harm to the environment. Defra's science programme has a central role to play in the development of its nitrogen pollution policies. These pollution policies provide a key input to the Department's evidence base for policy formulation, and support international negotiations on pollution targets. The Department's science programme has addressed the major components of the nitrogen cycle associated with harmful impacts on the environment and human health. The main aims have been the understanding and quantification of impacts through monitoring and modelling and the development of abatement measures. It is becoming increasingly apparent that whilst advances can and have been made in the reduction of emissions from combustion processes, the problem of nitrogen pollution from agriculture is far more intractable. This scientific challenge, when taken together with emerging regulatory initiatives, will require imaginative solutions if the UK Government is to forge a sustainable way forward.