Soil Quality Deteriorating in China, Threatening Public Health and Ecosystems

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China’s arable land, which feeds 22 percent of the world’s population, is facing grim pollution and degradation, warns Zhou Xiansheng, director of the State Environmental Protection Agency (SEPA), according to Xinhua News Agency. The decline in soil quality has become one of the most worrisome byproducts of China’s breakneck economic growth. Heavy metals are accumulating in the soil, hardening the soil surface and reducing its fertility, and residues from chemical fertilizers and pesticides are showing up in farm products, poisoning both people and livestock. Currently, about 10 million hectares of cropland—10 percent of the country’s total cropland area—has been contaminated, most of it in more affluent regions like the Pearl River Delta, SEPA officials noted in a recent national teleconference.

China’s farmers have used agricultural chemicals on their farmland for decades, as many consider this the most effective means of increasing yields and combating plant diseases. Xinhua News Agency reports annual use of more than 1.2 million tons of pesticides, which has resulted in the contamination of an estimated 7 percent of the country’s arable land. In 2004, China imported some $310 million worth of the chemicals, according to the Worldwatch Institute’s Vital Signs 2006-2007 report. Although this represented a 45 percent decrease in Chinese pesticide imports since 1995, the overall increase in global pesticide use is largely attributed to China’s rising use of herbicides on genetically modified crops.

Critics note that chemical inputs used extensively on China’s croplands are being applied inefficiently. For instance, nearly half of the nitrogen fertilizer applied in China evaporates or is washed away before being absorbed by crops, Gao Jixi, director of the Ecology Institute with the Chinese Research Academy of Environmental Sciences, told Xinhua News. The toxic runoff can affect cropland biodiversity and local water quality, over-enriching surface waters with nutrients and polluting groundwater with nitrates.

The other major culprit behind China’s worsening soil quality is industrial pollution. Statistics from the Guangdong Ecology and Soil Institute show that heavy metals such as mercury and nickel, mainly from industrial factories, are contaminating croplands in the highly industrialized Pearl River Delta region. The mercury production process discharges large quantities of untreated mercury waste into China’s rivers, directly polluting an estimated 2 percent of the river sources that irrigate cropland in Guangdong province. In most cities within the Delta region, the release of harmful industrial waste, together with steadily increasing vehicle emissions, is contributing to the accumulation of heavy metal residues in local crops and vegetables.

China’s long-boasted miracle of feeding the world’s most populous country using only 7 percent of the world’s arable land has come at considerable cost: according to SEPA, every year about 12 million tons of crops are contaminated with heavy metal residues, causing direct economic losses of more than 20 billion RMB (US $2.5 billion). The residues also threaten public health, contributing to diseases and other ill-effects. For example, the intensive use of bluestone solution, a copper sulfate compound used in insecticides and germicides, has led to widespread contamination of fruit that can cause chronic poisoning symptoms at higher intake levels. In China’s southern regions, the average volume of nitrate in vegetables is 70 percent above the national safety limit. When absorbed by human bodies, nitrate can deoxidize into nitrite, a known carcinogen.

Although its soil quality continues to deteriorate, China has yet to send clear signals on how it intends to tackle the problem. For decades, a lack of relevant legislation and effective measures, weak public awareness, and the absence of national standards for soil quality have all helped to accelerate the pace of soil deterioration. After the government released a white paper last month on environmental protection, however, SEPA beefed up efforts by announcing a one billion RMB (US $125 million) soil pollution survey, which will last three years. The survey will reportedly concentrate on key regions near heavily polluting factories, industrial sites, solid waste disposal sites, oilfields, mining areas, and major vegetable-growing bases. Experts expect a soil environmental quality monitoring and management system to be established by the end of the survey period.