Black soil is the best kind of soil, which is evolved from humus formed by long-term corrosion of surface vegetation under cold climate conditions. This kind of soil is famous for its high organic matter content, fertile soil and loose soil, which is most suitable for farming. There are only three black soil areas in the world: one is distributed in the great plains of Ukraine, with an area of about 6.5438+0.9 million square kilometers; Second, it is distributed in the Mississippi River basin of North America, with an area of about 6.5438+0.2 million square kilometers; Third, it is distributed in the black soil area in the northeast of Songliao Basin, covering an area of about 6.5438+0.02 million square kilometers. It is an important commodity grain base in China and is called "Beidacang". Because the black soil is fertile, these three black soil areas are all important agricultural products bases in China, so the reclamation index of the three black soil areas is relatively high.

The black soil area in Northeast China is located in Songnen Plain and its surrounding plateau hilly areas, starting from Nenjiang County in our province in the north, reaching Siping City in Jilin Province in the south and reaching the east and west sides of Daxinganling in the west. It evolved in the cold climate of Northeast China. After the death of surface vegetation, it was corroded for a long time to form humus. Due to the influence of temperate monsoon climate, the summer in Northeast China is hot and rainy, meadow herbs grow luxuriantly, and a large amount of organic matter is accumulated on the ground and underground. In the long and cold winter, the soil freezes, the microbial activity is weak, and the organic matter slowly decomposes, forming a thick black soil layer.

According to the researchers' calculation, it takes 400 years to form a black soil layer with a thickness of 1 cm. Northeast black soil is the main soybean producing area in China. The strong growth of soybean, corn, rice, sorghum, kidney bean and wheat makes it a "regulator" of national food security. Black soil area is also the main producing area of cash crops such as beet, flax, sunflower and soybean in China. However, in the past hundred years, with the continuous predatory exploitation of black land by human beings, the problem of soil erosion in black land has become increasingly serious. Experts even predict that if the current situation continues, black land will probably disappear in 50 years. Therefore, experts call for attention and protection of black land resources to prevent over-exploitation.