S3567 29/5/07 09:47 Page 1 the nutrient cycle: closing the loop S3567 29/5/07 09:47 Page 2 the nutrient cycle: closing the loop Edited by Hannah Hislop Green Alliance is an independent charity. For 28 years we have worked with businesses and other environmental charities to make environmental solutions a priority in British politics. We work with representatives of all three of the main political parties to encourage new ideas, facilitate dialogue and secure new commitments to action and progress on the environment. Designed and printed by Seacourt www.seacourt.net on paper with at least 75 per cent recycled content. © Green Alliance 2007 £5 ISBN 978-1-905869-03-9 Green Alliance 36 Buckingham Palace Road, SW1W 0RE tel: 020 7233 7433 fax: 020 7233 9033 email: [email protected] website: www.green-alliance.org.uk Green Alliance is a registered charity number 1045395 Company Limited by guarantee, registered number 3037633 Our thanks go to the Association of Rivers Trusts, the Environment Agency, Natural England, Northumbrian Water, the Pennon Group,Thames Water and Water UK for their support of this project.Thanks also to Clive Bates, Bob Breach, Jim Densham, Jane James and Helen Wakeham for their advice.The recommendations presented in this report are put forward by Green Alliance and do not necessarily represent the position of all project partners. S3567 29/5/07 09:47 Page 1 contents 1 foreword _02 Ian Christie, Green Alliance Associate the nutrient cycle: closing the loop _04 Jiggy Lloyd, Green Alliance Associate the water industry’s role in today’s nutrient cycle _13 Dr Stephen Bolt, ADAS recycling biosolids to land _19 Dr Stephen R Smith, Imperial College London the nutrient cycle: closing the loop the nutrient cycle: implications of farm management on the nutrients cycle _26 Professor Mark Kibblewhite, Cranfield University the role of composting in closing the nutrients loop _31 Dr Jane Gilbert, the Composting Association too much of a good thing? the impacts of nutrients on birds _35 and other biodiversity MA MacDonald, JM Densham, R Davis and S Armstrong-Brown, RSPB energy and cost implications of today’s nutrient cycle _39 Rob Lillywhite, Warwick HRI, Warwick University notes and references _43 S3567 29/5/07 09:47 Page 2 2 foreword Ian Christie, Green Alliance Associate Many of the environmental problems now seen as into the environment has brought immense short- contributing to unsustainable human development term gains in prosperity and output. But the price have this in common: they involve a relatively rapid could be long-term degradation of essential natural and large disturbance to the huge geochemical life-support systems – adding to the greenhouse cycles that help regulate the biosphere. Human effect, damaging water quality, reducing soil quality, sources of carbon dioxide and other greenhouse and soaking up resources in end-of-pipe pollution gases may not seem significant in the context of the control and damage limitation. whole Earth system or of geological time; but they have been sending a large enough volume of The nitrogen and phosphorus cycles are immensely emissions in a relatively short period into the complex and ‘leaky’, as made clear in the essays that the nutrient cycle: closing the loop the nutrient cycle: atmosphere such that the overall natural balance of follow.The policy challenges are also complex, the carbon cycle is being disrupted. involving many established commercial interests, dependence on manufactured fertilisers, and the “ the nutrient cycle demands The potential dangers from need for a radical shift in nutrient use so that we action on the least climate change as a result of ‘close the loop’ and recycle as many nutrients as this recent disruption of the possible. glamorous and electorally carbon cycle are now appealing aspects of dominating political debate. There is another important cycle to consider when environmental policy” There is a risk, given the we address these policy challenges.That is the complexity and scale of the political attention cycle.The fabled ‘top of the climate challenge, that another cycle of great political agenda’ is always a crowded place, and significance will be neglected.This is the nutrient environmental concerns cannot be guaranteed to cycle – made up of two great geochemical fluxes, remain there, with the exception (one hopes) of those of nitrogen and phosphorus.The essays in this climate action.The risk is that climate policy comes booklet explore the scale of the disruption that to dominate debate and action at the expense of human development has unwittingly brought to other, related challenges. Nutrients policy is these cycles. As with the carbon cycle, we have vulnerable.The nutrient cycle demands action on the overloaded natural systems in a short span of time as least glamorous and electorally appealing aspects of we have industrialised, and in particular as we have environmental policy – soil management, farming developed and applied synthetic fertilisers. Again, as systems, the treatment of sewage sludge and so on. with the carbon cycle, our injection of vast The nutrient cycle is not getting the attention it quantities of nitrogen and phosphorus compounds deserves. S3567 29/5/07 09:47 Page 3 The answer may be to see the disruption of the is a wide-ranging Defra review in hand on land use, 3 nitrogen and phosphorus cycles for what they are: and David Miliband has called for a national debate closely connected to the problem of the carbon cycle on a sustainable vision for land use over the long that is now rightly commanding attention from term – in this case the next 80 years. governments, civil society and business worldwide. For many of the current and projected problems Finally, the emerging debate about the mix of from climate disruption – over-heating, droughts, demands on farming – what the balance should be flash flooding and erosion – will interact with the between food production, management of landscape threats that nutrient overload poses for water quality and wildlife, and production of bio-fuels – provides and soils. We need to see the nutrients issue as a another opportunity to give the nutrient cycle the subset of a much bigger general problem – our prominence it deserves. As with the carbon cycle, the unwitting overloading of fundamental natural cycles realisation that we have managed to disrupt one of and life-support systems – and as a cluster of the great geochemical cycles should prompt urgent problems that could be exacerbated severely by rethinking of policies, technologies and attitudes, climate change. Dealing with the climate threat and and open up huge opportunities for innovation as the nutrients problem calls for a common approach we try to restore the balance we have lost. closing the loop the nutrient cycle: rooted in closed loop management of energy, water and nutrients, bringing emissions back into balance, and achieving the great gains in resource efficiency that we know we can make. So it will be important to make the “ we need to see the necessary connections between nutrients issue as a strategies for climate action and measures to close the nutrients loop, subset of a much many of which are discussed in the bigger general essays below.Another significant problem” opportunity to raise the profile of the nutrients cycle is offered by emerging debates on land use and the future of farming. In this respect two developments in 2007 are worth noting, both involving the Environment Secretary, David Miliband. First, there is his call for the agriculture sector to take seriously the concept of ‘One Planet Farming’, drawing on the growing interest in the ‘One Planet Living’ concept recently promoted by WWF and BioRegional. Second, there S3567 29/5/07 09:47 Page 4 4 The nutrient cycle: closing the loop Jiggy Lloyd, Green Alliance Associate “We are fertilising the Earth on a global scale and in other household products. Nutrients still cycle a largely uncontrolled experiment”, Global through the economy but the amount in circulation Environment Outlook, UNEP, 1999 is greatly increased. In the case of nitrogen, it is estimated that human activity has doubled the Society owes a lot to the nutrient cycle. As students amount in circulation; in the case of phosphorus, we of biology and geography know, virtually every have tripled the amount available since the industrial aspect of the modern economy is dependent on the revolution. fact that nutrients such as nitrogen and phosphorus circulate in different forms through water, air and This might not of itself be a concern but it needs to the soil. be considered alongside the indications that the nutrient cycle: closing the loop the nutrient cycle: nutrients are also, on some occasions, turning up in Depicted neatly in the typical school textbook the wrong place. diagram, the N-cycle and the P-cycle look almost too good to be true.They are ‘true’ – even if, as the A water industry spends significant amounts of expert contributions to this pamphlet remind us, money removing phosphates from wastewater.There they are more complex than the textbooks can does not appear to be a definitive figure but some convey.And they are certainly ‘good’, in the sense estimate it to be around £35 million a year. that life could not function without them and the Furthermore, between 2005 and 2010, English modern economy relies on them. But water companies will have to incur capital nutrients are also a source of pollution and expenditure of about £300 million and annual “ human activity the dangers of nutrient overload are operating costs of £6 million to reduce nitrate levels has doubled recognised. So the question has to be asked – for the public drinking water supply.