Where in China are brown calcic soils distributed, and what crops are suitable for growing there?

Brown calcic soil is an arid soil that forms a transition from chestnut soil in the temperate dry steppe zone to gray desert soil in the desert zone. Its formation is dominated by the humus accumulation process and calcic process of steppe soils, and it also has some characteristics of desert soil-forming processes. It has a thin humus loamy surface layer, the ground surface is mostly sandy gravel, the upper part of the profile is brownish brown, below it is brown weakly clayified, and the lower part is a powdery layered or patchy grayish white calcic horizon.

Brown calcic soil is mainly distributed in the temperate desert steppe regions of Eurasia, located between chestnut soil and desert soil, surrounding the outer periphery of desert soil on the west, north and east sides. In China it is distributed in the central and western parts of the Inner Mongolia Plateau and the Ordos Plateau, the northern part of the Junggar Basin, the outer edge of the Tacheng Basin, and the upper part of the piedmont alluvial fans on the northern slope of the central Tianshan Mountains.

The brown calcic soil distribution area has a temperate arid continental climate, with an average annual temperature of 2~7°C, an accumulated temperature of ≥10°C of 2200~3000°C, and annual precipitation of 150~250(300)mm. In the Inner Mongolia region affected by the southeast monsoon, 70% of precipitation is concentrated in early summer and autumn; in the northern Xinjiang region affected by the westerlies, precipitation is relatively evenly distributed across the four seasons. The total annual radiation in brown calcic soil areas reaches 600~670kJ/cm2, and light and heat resources are very abundant.

The vegetation of brown calcic soil has the characteristics of a transition from steppe to desert, and is divided into two subzones: desert steppe adjacent to dry steppe, and steppe-like desert transitioning to desert steppe. In the desert steppe of Inner Mongolia, it is often Stipa klemenzii and Stipa glareosa, accompanied by Artemisia frigida and Caragana stenophylla; the steppe-like desert is dominated by communities composed of the extra-xerophytic Caragana tibetica, Reaumuria songarica, Stipa klemenzii, Artemisia frigida, etc.; in northern Xinjiang, besides extra-xerophytic small semi-shrubs of the genus Artemisia, Anabasis, and small grasses such as Stipa glareosa and Stipa xinjiangensis, there are also spring ephemeral plants.

The brown calcic soil region is rich in light and heat resources, but water resources are scarce, so rainfed agriculture cannot be practiced. Where irrigation conditions exist, agriculture can be developed, and it is suitable for growing some drought-tolerant crops, such as foxtail millet, broomcorn millet, sorghum, sesame, peanut, buckwheat, castor, sunflower, sweet potato, corn, miscellaneous beans, wheat, yellow ginger, hot pepper, citrus, peach, cherry, garlic, carrot, chestnut, persimmon, wild jujube, sweet potato, potato, etc. The specific varieties chosen should be determined according to the local natural environment and soil conditions. Although there is a small amount of farmland in the brown calcic soil subclass areas, the yields are low and unstable; these are the so-called “chuantian” (opportunistic fields). At present they are mainly natural grazing lands in northwest China, for raising sheep and camels.