UK-China Project on “Improved Nutrient Management in Agriculture – a Key Contribution to the Low Carbon Economy”
China and the UK are committed to achieving a low carbon economy and slowing down climate change. Low carbon agriculture has a central role to play in achieving these objectives and one of the most critical actions is to improve nitrogen management. The manufacture and use of synthetic nitrogen fertilizer is currently estimated to account for some 9-15% of China’s total greenhouse gas (GHG) emissions as well as contributing to acid rain, water pollution, the increasing frequency of red tides and reduced farm incomes. There is also indisputable evidence of excessive nitrogen use in agriculture, with widespread proof that use could be cut by at least 30%, with no loss of crop production. Such a decrease would achieve savings of 2-3% in China’s total GHG emissions – with likely potential for even larger savings – and probably lower nitrous oxide emissions by >30%. Improved N management is a clear win-win action with economic and environmental benefits at all scales from the local to the global. But the required policy actions are multi-sectoral and will take 5-10 years or more to implement – so there is urgency to start immediately.
The case for action
China’s agriculture and agro-chemical industries account for about 15% of China’s total fossil energy use and 20% of total GHG emissions. The largest fossil energy input to China’s agriculture is that used to manufacture nitrogen fertilizer (about 70%). It is mainly coal (and some natural gas) burnt in factories that do not use the best available technologies so energy efficiency tends to be low and carbon dioxide and other GHG emissions are high. Moreover, most of this fertilizer is used inefficiently with average grain yields per unit of fertilizer being considerably less than those obtained in the UK and other developed countries. Fortunately, field trials in China over many years, crops and provinces show that the overuse of N fertilizer and other causes of low fertilizer use efficiency can be reduced substantially through improved nutrient management without any loss in yield and additional economic and environmental benefits. Much of the excess fertilizer is lost to the environment as gases or in water draining from the soil. The most serious gas is nitrous oxide which is 310 times more powerful than carbon dioxide in terms of its impact on global warming. But large amounts of ammonia are also lost from fertilizer and manure which contributes to acid rain and may be an important source of indirect nitrous oxide emissions from lakes and rivers. It follows, therefore, that one of the key actions to achieve low carbon agriculture in China is to reduce inefficiencies in the production and use of nitrogen fertiliser.
The magnitude of benefits
In 2008 synthetic N fertilizer production in China needed about 80 MT coal equivalent and N fertilizer use accounted for > 80% of fossil energy inputs into crop production. Consequently actions to limit the current 25-50% overuse of fertilizer N would make a major contribution to the achievement of a low carbon economy and GHG reduction. For example, a 25% reduction in N fertilizer use if translated into an equal reduction in the production and transport of fertilizer would avoid the release of some 50 MT CO2 eq. In addition, the 25% reduction in use by farmers would lower the direct and indirect losses of nitrous oxide and other GHGs by about 80 MT CO2 eq. as well as reducing acid rain, water pollution, red tides and boosting net farm incomes.
The opportunities for change
Chinese scientists have made considerable progress in devising improved N management practices to limit N overuse, but uptake by farmers has been limited by technical, institutional and socio-economic factors. Some of these factors are now being addressed and there are other technical and policy opportunities that could be developed. Restructuring and technological upgrading of the N fertilizer industry is another option but there will be a number of economic constraints to overcome.
The way forward
The UK used to suffer from serious nitrogen mismanagement but national and EU environmental legislation has forced farmers to be more efficient, and British natural and social scientists have extensive experience of technological and policy research to overcome these problems which they can share with their Chinese colleagues and help shape to suit China’s unique situation. Consequently, the UK and China launched this three year joint project in April 2009 to produce a more comprehensive evidence base to help China’s national and provincial policy makers to formulate and implement measures to improve nutrient management, lower direct and indirect GHG emissions and slow down climate change. The focus will be on synthetic nitrogen fertiliser use for crops, but the project will also considering links between crop and livestock production and the potential for improved manure use and organic fertiliser production.
Specific aims of the project include:
—Application of life cycle assessment to the manufacture and use of N fertilizer in China
—Review of current and emerging techniques for increased efficiency of N fertilizer use, building on results from the Ministry of Agriculture project “Fertilizer recommendations and soil testing”.
—Review of current and emerging techniques for increased efficiency of use of manure and organic manures and their role as substitutes for synthetic N fertilizers
—Assessment of improved ways of communicating to farmers, extensions workers and policy officials the multiple benefits of improved nutrient management, taking account of farmers’ economic and social situations
The project is funded by the UK’s Foreign and Commonwealth Office and by China’s Ministry of Agriculture. It will be led by Prof Zhang Fusuo, China Agricultural University, Beijing and Prof David Powlson, Rothamsted Research, UK. The project forms part of the China-UK Sustainable Agriculture Network – SAIN (see www.sainoline.org ).
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