original article:
http://www.nature.com/news/2011/110302/full/news.2011.131.html?s=news_rss
snippets:
Between 70% and 80% of agricultural greenhouse-gas emissions, such as nitrous oxide, come from the production and use of nitrogen fertilizers. So future rises in food production must be achieved without corresponding boosts in fertilizer use, added Gordon Conway, professor of international development at Imperial College London.
Conway heralded the 'fertilizer trees' Faidherbia albida as the future, particularly for farmers in Africa. These trees, which reintroduce nitrogen to the soil, have been shown to quadruple African maize yields in soils with no artificial fertilizer added.
But David Powlson, a retired soil scientist with a visiting professorship at the University of Reading, UK, urged caution. He says that countries' fertilizer use should differ according to their stages of development, particularly in Africa, which has soils that are starved of key nutrients such as nitrogen and phosphorus.
The overuse of nitrogen fertilizers elsewhere in the world, such as in China, "should not be used as an excuse not to give nitrogen fertilizers to Africa", he says.
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