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China's Environment

Unsustainable agricultural practices attract attention

by Jean-François Tremblay
February 22, 2010 | A version of this story appeared in Volume 88, Issue 8

Credit: Science
A Chinese farmer applies nitrogen fertilizer to crops.
Credit: Science
A Chinese farmer applies nitrogen fertilizer to crops.

China’s first national census of pollution sources reveals that agriculture plays a major role in damaging the country’s environment, according to China’s Ministry of Environmental Protection. In the past, China mostly blamed industry for its increasingly serious environmental woes.

China relies primarily on chemical oxygen demand, a measure of the mass of oxygen consumed per liter of water, to quantify the level of pollution in its rivers. By that yardstick, the census found that agriculture accounted for 43% of the country’s water pollution in 2007. According to a statement released by the ministry, livestock and poultry are the main contributors of pollution from agricultural sources. Costing about $100 million and involving 570,000 workers, the census took two years to complete.

Focusing solely on chemical oxygen demand to measure water pollution could be misleading, says Jamie Choi, head of Greenpeace China’s campaign against toxic chemicals. In a recent interview with C&EN, she said that China does not keep track of the quantities of toxic substances, such as mercury, that are released into the environment, mostly by industry (C&EN, Jan. 4, page 14).

Although it might provide an incomplete picture of the extent of pollution in China, the new census brings attention to the country’s unsustainable agricultural practices. Between 1981 and 2007, China nearly tripled its use of nitrogen fertilizer, according to a paper recently published in Science (DOI: 10.1126/

China’s “extraordinarily high” rates of nitrogen fertilizer application compared with Europe and North America have degraded soil and environmental quality, the paper’s authors write. Their survey of 154 agricultural fields for which data from the 1980s exist, they say, indicates a “widely occurring soil acidification in Chinese croplands.”


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