Nitrogen: the essential public enemy

Abstract

Summary 1.Increased demand for food and energy is leading to changes in the global nitrogen cycle. These changes are resulting in increasing levels of nitrogen in the environment in its pollutant forms with consequences for both biodiversity and human health. 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. 2. 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. 3. 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. 4. 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. 5. 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. 6. Synthesis and application. 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.

Seminatural grassland management by mowing ofCalamagrostis epigejosin Hungary

“…Using space for time substitution, we assumed that all stands had the same history and the same landscape context. Contrary to this assumption, conditions changed considerably and the abandonment of grazing and mowing become typical in the recent decades (Poschlod & Wallis de Vries 2002;Lindborg 2006) parallel with the eutrophization of the environment (Dalton & Brand-Hardy 2003). In these changed environments, the C. epigejos might get an advantage, it spreads and it has prolonged dominance.…”

Assessing the impacts of agricultural intensification on biodiversity: a British perspective

“…Of all the pressures caused by crop management on biodiversity, the excess of nitrogen and phosphorus is perhaps the most ubiquitous and difficult to manage (Heathwaite et al 1996;Tilman et al 2001;Dalton & Brand-Hardy 2003), even more so than the effects of pesticides that can be much more localized (Roy et al 2003). Excess nutrients result in pervasive impacts on both terrestrial (Smart et al 2003b) and aquatic (Carpenter et al 1998) biota (Dalton & Brand-Hardy 2003;Millennium Ecosystem Assessment 2005b). Indeed, one of the most consistent changes in British vegetation over recent years is the eutrophication signal in mid-successional plant communities typical of low or moderate productivity (Smart et al 2003b).…”

Meeting the ecological challenges of agricultural change: editors’ introduction

“…We are increasingly wellinformed not only about the processes that affect associated ecological systems (McLaughlin & Mineau 1995;Vickery et al . 2001;Robinson & Sutherland 2002;Dalton & Brand-Hardy 2003), but also those through which organisms, populations and communities respond (Fuller et al . 1995;Siriwardena et al .…”

“…2001). Large-animal grazing can affect the conditions for seed survival in scarce plantsboth directly or indirectly by altering populations of Dalton & Brand-Hardy 2003 Reviewed the impacts of excess agricultural nitrogen. Benton et al .…”