Irrigation-silted soils siltigi-orthic anthrosols are mainly distributed in the arid areas in northwest China, including
the north piedmont of the Kunlun Mountains and the south and north piedmonts of the Tianshan Mountains in Xinjiang, the Hexi Corridor in Gansu Province, and the Hetao area in Ningxia Hui Autonomous Region and Inner Mongol Autonomous Region, and
irrigation-silted soil is also sporadically distributed in other provinces and autonomous regions. The total area of irrigation-silted soils in China is 1.5×106 hm2, in which the area in Xinjiang occupies over 60%. In this paper, the formation and taxonomy of irrigation-silted soils in China are researched. The results are as follows: (1) Irrigation-silted soils are different from other arid soils because of its irrigation-silted layer and moisture regime; (2) The thickness of the irrigation-silted layer is thicker than 50 cm, thus the original soils, such as gleysol soil and salty soil, are buried; (3) Sedimentary stratification of irrigation-silted soils disappears under the conditions of cultivation, fertilizing and irrigation, so this kind of soil is different from the alluvic primosols with alluvial stratification; (4) Because of the seasonal irrigation, the irrigation-silted soil is different from the stagnic
anthrosols under the anthrostangnic moisture regime; (5) Irrigation-silted soil is also different from the fimi-, earth-cumuli-or mud-cumuli-orthic anthrosols.