Chinese scientists are warning that the country's northeast breadbasket regions are in danger of losing their fertility because of soil erosion and degeneration.

"The northeast areas are the granary of the country. Soil erosion and degeneration will jeopardize the nation's grain security," said Zhang Xudong, a soil expert with the Shenyang-based Institute of Applied Ecology under the Chinese Academy of Sciences (CAS).

China's expanse of black soil, spanning Heilongjiang, Liaoning and Jilin provinces and part of Inner Mongolian Autonomous Region, covers more than 35 million hectares. It is one of the three largest black soil areas in the world, along with similar land masses in Ukraine and the United States.

Studies by the Northeast Institute of Geography and Agro-ecology under the CAS and the Heilongjiang provincial soil retention research institute show the thickness of the soil has dropped dramatically from more than 80 centimeters to less than 30 centimeters in the last 60 years.

The density of organic substances in the soil has fallen from 12 percent in the 1940s to less than 2 percent, experts said, adding that about 85 percent of the soil is lacking sufficient nutrients.

The crescent-shaped black soil belt is a leading commodity grain base in China, accounting for 30 percent of the country's total grain output. Its yields feed 10 percent of the country's population.

However, excessive farming, overuse of fertilizers and relentless logging have caused erosion and degeneration of the soil quality.

Soil erosion has adversely affected local ecology, resulting in more frequent droughts, floods and sandstorms, said Yan Baixing, a researcher with the Northeast Institute of Geography and Agro-ecology.

The Heilongjiang Province has suffered spring droughts for 10 consecutive years. Soil became dust, blew away and became sediment in rivers and lakes, raising the river beds and increasing flood risks in the rainy season, Yan said.

"We need do everything to protect the soil from erosion and degeneration now. If we don't take action now, history will be repeated," Zhang said.

Zhang referred to the "dust bowl" disasters which hit the United States in the 1930s, caused by decades of extensive farming that promoted erosion coupled with severe drought. The soils amassed in dark clouds, blackening sky and forcing the exodus of millions at the time.

"We can't kill the goose that lays the eggs. The land must not be farmed in a destructive way," said Zhang.

Last week, China's National Development and Reform Commission (NDRC) issued a plan aimed to rejuvenate the northeastern provinces. Protection of the black soil is an important part of their agenda.

"Protecting the soil doesn't mean we have to cut more trees to develop arable land. What we need to do is to reinforce the irrigation facilities, and do everything we can to transform the low-yield crop fields into high-fertility land," said Zhang Guobao, NDRC Vice Minister, at a press conference.

Researchers said more ponds and reservoirs need to be built to restore soil moisture, and forest belts need to be in place to stabilize the soil. They are also encouraging farmers to leave manure and corn stalks in the field to increase nutrient content.

More than 100 million tons of natural fertilizers like manure and corn stalks are produced every year in northeast China, Zhang Xudong said. If used effectively, they could enrich about 5 million hectares of low-yields cropland in five to 10 years, he added.

(Xinhua News Agency August 28, 2007)