Where are the three largest black soil zones in the world?

There are three famous black lands in the world: one in America - the Mississippi River Basin of the United States; one in Europe - Ukraine on the Dnieper River; and one in Asia - the Pine Trees of China. Liao River Basin and Sanjiang Grassland.

In the Mississippi River Basin of North America, the black soil area is about 1.2 million km2. The Mississippi River originates from the mountains in the northern section of the Rocky Mountains in the north-western part of the United States. It meanders for thousands of miles, winding through the Great Plains of the United States from north to south, and empties into the Gulf of Mexico, with a total length of 3,950 kilometers.

Most of the Mississippi River is plain. The mouth of the Ohio River is 25 kilometers wide. The valley gradually widens along the river, and can be as wide as more than 100 kilometers. Most of the valley bottom has become swampy, and the river is extremely curved, with many old river beds and meanders. The soil here is fertile and it is the largest corn producer in the United States.

On the lower reaches of the Mississippi River, there is Memphis, the largest port city. It is a large distribution center for agricultural and livestock products in the United States, especially famous for the production of cotton, cottonseed oil and hardwood. A base for agricultural machinery manufacturing, automobile assembly, pharmaceuticals, wood and agricultural products processing has now been formed.

The Ukrainian Great Plains on the banks of the Dnieper River has a black soil area of ??about 1.9 million km2. It is known as the "Granary of Europe". The Dnieper River is the third largest river in Europe. It originates from the southern foothills of the Valdai Hills in Russia, flows through eastern Belarus and central Ukraine, and empties into the Dnieper Gulf of the Black Sea. 2200 kilometers long. The basin area is 504,000 square kilometers.

Black soil is distributed in forest-steppe zones and grassland zones. The total area of ??forest and grassland areas is 20.2 million hectares, accounting for 34% of the total land area and more than 37% of the country's cultivated land area. Among them, black and gray forest soil accounts for 21% of the zone, and typical black soil accounts for 51%. The total area of ??grassland is 23 million hectares, accounting for 38% of the total land area. This area is basically black soil. Among them, black soil in northern climate conditions generally accounts for 64% of the cultivated land area in this zone, and black soil in southern climate conditions accounts for 23%.

China's black soil areas are mainly distributed in the Songliao River Basin and Sanjiang Grassland in my country, covering an area of ??about 1 million km2. It is known as the "North Dacang" and is an important commercial grain base in my country. This area has a cold temperate climate, with a dry and cold climate. Rainfall mostly occurs in the form of heavy rains. The rainfall from July to September accounts for about 70% of the annual rainfall. The average annual rainfall is 400-700mm, the total water resources are 141.599 billion m3, and the per capita occupancy is 1213.98m3. The cultivated land area is about 21.3 million hm2, and it is also the industrial base of my country's petroleum, chemical, steel, automobile, forestry and other industries.

During the development process, black soil has experienced serious water and soil erosion. The Great Plains of Ukraine was the main food base of the former Soviet Union. Due to large-scale grass destruction and land reclamation, crops are grown only once a year, and the surface is exposed for too long, making it easy for large-scale wind erosion disasters to occur in spring. In the United States, before 1930, a large number of immigrants migrated to black soil areas, large areas of grassland were reclaimed, surface vegetation was destroyed, and soil and water conservation functions were completely lost. The black soil belt in Heilongjiang Province is being eroded by wind and sand. The latest survey shows that the desertified land area in this province has accounted for 6.1% of the province's land area, and it is continuing to expand. The Nenjiang Sandy Land, currently the most severely desertified area, is located on the alluvial plain of the lower reaches of the Nenjiang River at the eastern end of the sandstorm line in northern China. It is about 165 kilometers wide and 300 kilometers long, with a total area of ??more than 1,800 kilometers. Thousands of hectares.

Soil erosion in black soil areas: (1) loss of precious black soil resources, (2) reduction of land productivity, (3) reduction of cultivated land and destruction of homes, (4) sedimentation, affecting flood control safety.

Comprehensive management of water and soil loss in black soil areas implements the water and soil conservation policy of "prevention first, comprehensive planning, comprehensive management; adapting measures to local conditions, strengthening management, and focusing on benefits", and implements mountain, water, and field management based on small watersheds. Comprehensive management and development of forests, roads, and roads. According to different soil erosion types, landform types, and water and soil loss characteristics, various management measures should be configured according to local conditions. At the same time, engineering measures, forest and grass measures, and farming measures should be organically combined to better achieve better results. Give full play to the role of various governance measures.

Relying on natural restoration capabilities, we will comprehensively protect the existing natural forests, artificial forests and grasslands in each project area, and close the mountains for forest and grass cultivation. Carry out planned replanting and protection of existing sparse forest land to increase forest and grass coverage, enhance water and soil conservation and erosion resistance, and prevent water and soil erosion in sparse forest land.

Rationally deploy gully control projects and slope interception projects in barren mountains and wastelands, vigorously build soil and water conservation forests, establish a protective forest system, and increase vegetation coverage.

In the Manchuan and Manggang areas, due to the high reclamation index and low ground forest and grass vegetation rate, the management of sloping farmland should be focused. The main measures are: changing slope ridges to horizontal ridges, building plant ridges, slope terraces and horizontal terraces and other engineering measures. We will build high-standard basic farmland, create farmland protection forests, and promote the return of farmland and large-area enclosure and protection.

In hilly and ravine areas, we mainly focus on ditch management on the basis of comprehensive slope management, and adopt comprehensive measures such as restoring vegetation, intercepting surface runoff, building ditch projects, and building basic farmland to establish Complete gully protection system. Control the further development of scouring and erosion gullies on both sides of the bank to achieve the purpose of protecting black soil.

In wind-eroded areas, the main focus is to rationally develop and utilize water resources, build basic pastures, develop efficient agriculture and animal husbandry, and create conditions for grassland protection and large-scale vegetation restoration.