, Volume 80, Issue 2, pp 189-198
Date: 31 Aug 2007

Impacts of population growth, changing food preferences and agricultural practices on the nitrogen cycle in East Asia

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Abstract

While increasing population and changing food preferences have changed agriculture in some East Asian countries to high input systems with greater use of fertilizer nitrogen and greater numbers of animals, the changes and the effects on the environment in the different countries have varied considerably. Many areas still do not use sufficient nitrogen to maximize crop yields. In China, fertilizer nitrogen input has increased from 0.54 Tg in 1961 to 28 Tg in 2005, and the animal population increased dramatically, from 27 to 1,013 million. As a result 13 Tg N was lost to the environment in 2005 as nitrous oxide, ammonia or nitrate. In Mongolia, no fertilizer nitrogen was recorded as having been used until 1970, and current use is only ∼4 Gg. The animal population has increased from 23 million in 1961 to 28 million in 2005 and adverse effects on the environment are small (96 Gg N lost). However, a combination of over-ploughing and overgrazing has resulted in soil erosion from wind and rain in both countries and loss of soil nitrogen. These and other effects of changing agricultural systems on the nitrogen cycle in East Asian countries and some approaches to reduce the impact of nitrogen on the environment are reported in this paper.