Where in China is brown earth distributed, and what is it suitable for growing?

Brown earth is a widely distributed soil type in northern China and is an important forest and agricultural soil. So, where exactly in China is brown earth distributed? And what is it suitable for growing?

Brown earth, also called brown forest soil, is a soil formed under warm-temperate deciduous broad-leaved forests and mixed coniferous-broad-leaved forests. Its main characteristics are a slightly acidic reaction and a freshly brown subsoil horizon (B horizon); the parent material is mostly weathered acidic bedrock. The climate of brown earth regions is characterized by warm, hot and rainy summers and cold, dry winters, with an average annual temperature of 5-14°C, an accumulated temperature above 10°C of 3400-4500°C, a seasonal frozen layer reaching 50-100 cm deep, annual precipitation of about 500-1000 cm, a dryness index between 0.5 and 1.0, and a frost-free period of 120-220 days. However, owing to the influence of the southeast monsoon, land-sea position and topography, the regional differences between east and west are extremely obvious.

Brown earth is widely distributed in Europe, such as in Britain, France, Germany, Sweden, the Balkan Peninsula and the southern mountainous areas of the European part of the former Soviet Union. In North America it is distributed in the eastern United States, and in Asia it is mainly distributed in China, northern Korea and Japan.

In China, the distribution of brown earth runs across the Liaodong and Shandong Peninsulas, with the belt running roughly in a northerly direction. In addition, in the mountains of semi-humid and semi-arid areas, such as the Yanshan, Taihang, Songshan, Qinling, Funiu, Lüliang and Zhongtiao Mountains, brown earth is distributed above the cinnamon soil or leached soil in the vertical zonation, as well as in the upper parts of the mountains in the yellow-brown earth region of the south.

Brown earth and cinnamon soil are leached and semi-leached soils distributed in China's warm zone humid forests and semi-humid dry forests and shrub steppes. They generally occur in high plain landform positions between 36-44°N and 112-128°E, including the Liaodong Peninsula, the Shandong Peninsula, the southern foot of the Yanshan Mountains, the North China Plain and both sides of the Taihang Mountains, the southeastern foot of the Loess Plateau and the Guanzhong Plain. Administratively this includes the provinces, municipalities and autonomous regions of Jilin, Liaoning, Shandong, Hebei, Beijing, Tianjin, Shanxi and Shaanxi. It is a major agricultural and fruit-producing region in northern China, especially for the three major crops of wheat, corn and cotton, as well as fresh and dried fruits such as apples, pears and Chinese chestnuts.

The brown earth region has good ecological conditions, abundant biological resources and relatively high soil fertility. The brown earth region has become an important production base for China's development of agriculture, forestry, fruit trees, tussah silkworms and medicinal materials. Subtropical mountain brown earth is distributed in a vertical belt at 1500-3600 m and is a production base for timber forests and water-conservation forests in the southwest. For example, in the mountain brown earth of the Beiyunling-Shaluli Mountains in northern Yunnan and the southern area, the north slope is dominated by spruce, while the south slope, besides spruce forest, also has alpine pine forest and alpine oak forest; the soil is fertile, the organic matter content is high, and the timber yield is also high.

However, at present, timber harvesting is excessive, the ecological environment is deteriorating, soil erosion is severe, and natural disasters are frequent; in many mountainous areas, mudflows of varying degrees occur from time to time. The focus of transformation and utilization is that natural regeneration of spruce forest bases is difficult, so artificial regeneration can be adopted, planting larch, alpine pine, Chinese pine, Huashan pine, spruce and so on. Develop water-conservation forests, timber forests and fuelwood forests to conserve soil and water and recharge water sources. At the same time, make full use of the vast understory grasslands and interforest grasslands to develop herbivore-based animal husbandry; organize the gathering and digging of wild medicinal materials, protect the rare birds and beneficial animals in the forest, and create better environmental conditions for the survival and reproduction of wildlife.

From the perspective of soil utilization, brown earth is an important forest soil and also an important agricultural soil, with great economic value. Chao brown earth is distributed on piedmont diluvial plains, is used for agriculture, and mostly gives stable yields despite drought or excessive rain, making it an important grain production base. Ordinary brown earth is distributed on mountain feet and gentle hilly slopes and is also mostly used for agriculture; part of it suffers relatively severe soil erosion and has poor water and fertilizer conditions, requiring soil and water conservation measures, further irrigation development and strengthened fertilization. Some bleached brown earth is distributed on denudational accumulation hills and is mostly used for agriculture, with very low fertility, requiring improvement; some is distributed in mountains and is mostly used for forestry. Acid brown earth is distributed in mountains and is mostly used for forestry; some is still barren hills and requires tree planting and afforestation. Coarse skeletal brown earth distributed on low hills is mostly used for growing peanuts and oak stands (for raising tussah silkworms); that distributed on high hills and mountains is mostly barren hills and open woodland, and soil erosion is very severe in all cases, so soil and water conservation measures should be adopted urgently.