The technology is important for it can help preserve the status of northeastern region as China's largest granary and prevent the black earth belt from disappearing.

A similar five-year research program was recently completed by a group of experts with the Heilongjiang Agricultural Modernization Research Institute, affiliated with the Chinese Academy of Sciences.

Program head Meng Kai said that the researchers have discovered that the imbalance between nutrient and moisture content of the black earth in the Heilongjiang and soil erosion constitute the main hindrances to growth of crops in different types of black earth.

Meng said that the crescent-shaped black earth belt, covering parts of northeastern Heilongjiang and Jilin provinces, is the most fertile land in China.

At present, more than 7 million hectares of the 10-million- hectare black earth belt have been developed into the largest commodity grain production base of the country, the grain output from which accounts for more than 60 percent of the two provinces' total.

Compared with the other two black earth belts in the United States and Ukraine, the black earth belt in northeastern China was developed earlier.

Lack of protection in the past has resulted in the disparity between crop-growing and conservation of the black earth. In addition, serious soil erosion has occurred and the organic matter in the black earth has dropped by more than 50 percent.

Still worse, the black earth layer is 0.3 to 1 centimeters thinner on average than the original 30 to 100 centimeters.

Experts said that the black earth layer might disappear within 50 years if action is not taken now, especially as the drop in soil fertility has led to the reduction of grain output by 30 percent.

Chinese researchers found that factors that curb the growth of crops are different in varying thickness of the black earth. Such factors are lack of nutrients and moisture for crops in the middle and late growth stages, adverse changes of soil structure and decline of nutrition, and lack of bioactivity.

To overcome the obstacles to the crop growing on the black soil, the researchers adopted mechanical, chemical and biological technologies to improve the physical structure of the soil and adjust the make-up of nutrients to raise the fertility of the black earth.

As a result of the measures, the per hectare grain output rose by more than 10 percent, totaling over 420 kilometers; the use ratio of fertilizer and moisture all went up by 10 percent, respectively; and the organic matter in the soil began to rise.

Sources from the Ministry of Agriculture said that effective protection of the black earth in northeast China will play a key role in China's goal of achieving an extra 140 million tons of grain by 2030.

(Xinhua News Agency 09/27/2001)