- China's economic revolution is coming at a cost. While
improved prosperity and government incentives convinced millions of people
to give up the rural life and move into towns and cities, China's
agriculture
is in rapid decline, prompting fears that the country that is home to
one-fifth
of the world's population will soon be unable to feed itself.
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- Those fears have been heightened by two new reports by
Chinese scientists. They reveal that a national push to encourage farmers
to abandon the millennia-old tradition of growing rice in favour of fruit
and vegetables is having a profound and detrimental affect on the quality
of China's soil and water.
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- After just five years, fields growing fruit and
vegetables
are becoming more acidic and barren, while nitrogen and phosphorus levels
and fungal epidemics are rising sharply.
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- Since 1998, the area of land in China devoted to grain
crops has fallen by 15 per cent. In August, Beijing confirmed that grain
yields have fallen by a fifth in that time, and consumption in 2004 is
expected to exceed production by a record 37 million tonnes. This demand
for imported grain has triggered a 30 per cent rise in global grain prices
in 2004, and further rises are expected as Chinese demand soars.
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- The root problem is that China is urbanising fast.
Already
500 million Chinese live in towns and cities, and the government wants
that to rise to 800 million by 2020. Cities are spreading across former
farmland and are getting first call on scarce water resources.
-
- They are also changing food markets: while prices for
grains such as wheat and rice are capped by the government, city people
are willing to pay high prices for fruit and vegetables. And the government
is encouraging millions of farmers to meet this soaring demand by
converting
rice and wheat fields to growing these more profitable crops.
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- More acidic
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- As a result, in the past decade, farmers have converted
13 million hectares, an area the size of England, to fruit and vegetables.
It is this unprecedented change that has triggered the new concern about
deteriorating soils.
-
- Researchers from the government's Institute of Soil
Science
in Nanjing have found that soils in fields converted to growing vegetables
are becoming dramatically more acid, with average pH falling from 6.3 to
5.4 in 10 years. Meanwhile nitrates in the soils are at four times previous
levels, and phosphate levels are up tenfold (Environmental Geochemistry
and Health, vol 26, p 97 and p 119).
-
- The changes in soil chemistry have been accompanied by
an equally dramatic decline in soil bacteria and an epidemic of fungus.
The deterioration is worst when the crops are grown under plastic.
-
- These changes are starting to hit vegetable yields and
quality. "Some plants show abnormal growth, deformed fruits and
various
plant diseases which are not easy to control by the usual pesticides,"
says Cao Zhihong of the Institute of Soil Science. There is, in addition,
"wide concern because of possible groundwater and well drinking water
pollution by leached nitrates and phosphates". Already, a third of
well water exceeds government norms for nitrate.
-
- "Anything that disrupts microbial activity and
function
in soil could be expected to affect long-term soil productivity, and have
serious consequences," says Rui Yin, a co-author of the
studies.
-
- Western agronomists suggest that changes in soil
chemistry
are not being caused by growing fruit and vegetables, but by farmers
applying
too much fertiliser to them. While China harvests a similar amount of the
crops to the US, it uses almost twice as much fertiliser, says Lester
Brown,
president of the Earth Policy Institute in the US and an expert on Chinese
agriculture.
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- http://www.newscientist.com/news/news.jsp?id=ns99996399
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