Characteristics of black soil, loess and red soil and their distribution in my country

my country’s black soil is located in the temperate semi-humid area. The four distinct seasons are characterized by rain and heat in the same season. The soil parent material is heavy and has seasonal frozen soil layers. Summer and autumn are rainy, and the soil often forms stagnant water in the upper layer. Herbaceous plants are luxuriant in the meadows, and a large amount of organic residues enter the soil both above and below ground. During the long winter, microbial activity is suppressed, organic matter decomposes slowly, and is converted into a large amount of humus that accumulates in the upper part of the soil, forming a deep black humus layer. The salt base in the soil is leached, and the carbonates are also moved out of the soil, making the soil neutral to slightly acidic. Seasonal stagnant water in the upper layer causes iron and manganese in the soil to be reduced and oxidized in the dry season to form iron and manganese nodules, especially in the subsurface layer. Therefore, black soil is formed by intense humus accumulation and stagnant water accumulation. It is a special meadowization process. Under natural conditions, the humus layer of black soil can be up to 1 meter thick, rich in nutrients and with high fertility levels. After the black soil is reclaimed, the humus content decreases. Because the parent material is heavy, soil erosion is obvious. This is a problem that requires attention in the utilization of black soil. Black soil is one of the most fertile soils in my country, and black soil distribution areas are important food bases. Suitable for a wide variety of species, especially suitable for the growth of soybeans, corn, millet, wheat, etc.

Loess is distributed in the entire Yellow River Basin south of the Great Wall, north of the Qinling Mountains, east of Qinghai in the west, and to the sea in the east. North of the Great Wall, the loess gradually disappears. In addition, it is worth noting that loess is also distributed in the northern foothills of the Tianshan Mountains, the foothills of the Kunlun Mountains, and the foothills of the Qilian Mountains. It is generally believed that the distribution of loess in China stops at the Qinling Mountains in the south, but in fact loess is also distributed south of Baoji, in the Fengxian and Shuangshipu areas of the Qinling Mountains, and further south to Chaiguan Mountains. There are sporadic loess distributions even in the Hanzhong Basin or eastward to the northern slopes of the Dabie Mountains, northern Jiangsu, and even near Nanjing and in some areas of the Yangtze River Basin.

Red soil in China is mainly distributed in the low mountainous and hilly areas south of the Yangtze River, including: most of Jiangxi and Hunan provinces, southern Yunnan and southeastern Hubei, Guangdong, northern Fujian, Guizhou, Sichuan, Parts of Zhejiang, Anhui, Jiangsu, etc., as well as southern Tibet and other places. Red soil is acidic – a strong acid reaction. Hilly red soil generally has insufficient supplies of nitrogen, phosphorus, and potassium, and the content of available calcium and magnesium is also low, and boron and molybdenum are also very poor. And often due to the lack of trace element zinc, citrus "mosaic" phenomenon occurs.