The color of the soil under the sun can reflect the changes in the inner nature of the soil, which is an important basis for the division of soil levels and the study of soil properties. The depth of the soil color is related to humus, humus content, the soil is black, such as the northern cold black soil; humus content is less, the soil is gray, such as the gray desert soil in Xinjiang. Soil color is also related to the type of compounds contained in the soil, iron hydroxide is red, more in the soil, the soil will show varying degrees of red, brown red and brownish-yellow; silicon dioxide, calcium carbonate, kaolin, aluminum hydroxide, etc. is white, the soil contains any one of these compounds, that is, gray, gray, or yellowish-gray.
China's soil distribution
Affected by climate, temperature, moisture, soil types are diverse, there are about 61 soil types in China, mainly black soil, white soil, brick red soil, brown soil, loess, red soil, small soil, clay, sandy soil, dark brown hustle, white slurry soil, gray desert soil, yellow sheen soil, red clay soil, sandy soil, purple soil, tidal soil (light-colored meadow soil), and swamp soil, rice irrigation and siltation soil and irrigation and desert soil.
Among them? Black soil is one of the best quality of soil. Cold climate conditions, the surface vegetation for a long time corrosion of humus formation evolution, the formation of black soil. This soil is known for its high organic matter content, fertile soil, loose soil, the most suitable for farming. From the global point of view, can be called the black soil area, there are three places, one is the Great Plains of Ukraine, one is the Mississippi River Basin, and then one is China's northeastern Songliao Basin, due to the influence of the temperate monsoon climate, the Northeast region of the summer high temperature and rainy, meadow herbaceous plants grow luxuriantly, the accumulation of large quantities of organic matter on the ground and under the ground, in the long cold winter, the soil freezes, the microbial activity of microorganisms is weak, the organic matter is slowly decomposed, and gradually formed a piece of 60 to 100 centimeters. Gradually formed a 60 ~ 100 cm humus layer of black soil, black soil in the Northeast region has an area of about 700,000 square kilometers, accounting for about 1 / 5 of the global area of black soil.
The Northeast region as a result of the spread of black soil, of which 1/4 is the "king of the soil" of the typical black soil, the soil is all black, black calcium soil and meadow black soil, very suitable for crops. Black soil, very suitable for the growth of crops, thus bringing the "black soil oil, not on the fertilizer also grow food", "randomly inserted willows into the shade, hand grabbed a handful of clutching out of the oil" home, the Northeast's black soil is China's main soybean production areas, thriving growth of soybeans, Corn, rice, sorghum, kidney beans, wheat, so that here has become the national food security "regulator", the black soil area at the same time is China's sugar beet, flax, sunflower, soybeans and other cash crops, the main producing areas. China's food security has outstanding strategic significance.
Besides the north? What does the soil in the south look like?
Most of the south of China is located in the tropical and subtropical regions, where a variety of red or yellow acidic soils are widely distributed, from the south to the north of the brick red soil, dry red soil (savanna soil), red red soil (brick red soil red soil), red soil and yellow soil types.
The red soil is the soil with the largest distribution area in China, which is distributed in the vast low hills south of the Yangtze River, including Jiangxi, most of Hunan, in addition to Yunnan, Guangxi, Guangdong, Fujian, the northern part of Taiwan, as well as Zhejiang, Sichuan, Anhui, the southern part of Guizhou have red soil distribution. The total area is about 1.17 million square kilometers, the red soil is formed in the middle-subtropical climate conditions, the natural vegetation is evergreen broad-leaved forest. Under the condition of high temperature and high humidity, the minerals undergo strong weathering to produce a large number of soluble salt groups, silicic acid and aluminum-containing iron substances? The salt base and silicic acid enter the groundwater and flow away. Aluminum-containing iron substances, on the other hand, accumulate and under dry conditions dehydration occurs to form anhydrous Fe2O3 and Al2O3, and red hematite gives the soil a reddish color. This area is a production base for tropical and subtropical forests, fruit trees and food crops in China due to high temperatures, abundant rainfall and favorable natural conditions.
Zhejiang is a multi-desirable agricultural area. Red loam rice soil is its main soil type, as early as 7000 years around the time of rice cultivation, to the Spring and Autumn grain crops have been Jik, millet, adzuki beans, rice, wheat, soybeans, barley barley and so on 7 kinds. Zhejiang's cocoon production ranks third in the country, citrus production ranks fourth in the country? Known plants more than 3,800 species, forest coverage of 60%, is the southeast of China's botanical treasure trove.
Fujian's typical soil is red and reddish soil, soil desilication and aluminum-rich role and biomass cycle are more active, weathering leaching is strong, iron free degree is high, making the soil red. Because of its good soil conditions, but also has a mild climate, is a fruit country, because the red soil is acidic soil, suitable for planting tea, so tea is the traditional characteristics of Fujian products, tea production ranks first in the country, oolong tea is cultivated in Fujian.