ALFISOLS AND CLOSELY RELATED SOILS IN CHINA

Key words: 
• alfisols /
• distribution /
• classification

Abstract: Alfisols are important soils in China. They occupy about 1.25 million km², or about 13% of the land area. In the current Chinese system of soil classification, burozem, yellow-brown earths, Baijiang (Planosol) soils and parts of drab soils. They are mostly forested soils with an estimated 5-13 t/ha·yr of organic matter returned to the soils from temperate mixed conifer and broad-leaved forest. In terms of elemental bio-cycling, Ca is prominent.In a comparison of 30 profiles the average ratio of clay (B/A) was 1.47 for Cryoboralfs and Eutroboralfs; 1.88 for Hapludaifs and 2.53 for Paleudalfs. From Eutroboralfs to Paleudalfs the average gain (or loss) in clay during soil development is about a factor of seven.The moisture regimes vary considerably between Hapludaifs, Cryoboralfs, and associated Cryaquepts, but the amount of water is always enough to cause significant leaching. In the weathering, and pedogenesis processes TiO₂, MgO and Fe₂O₃ are accumulated, respectively, in both AΔ and BΔ horizons;but SiO₂ and Al₂O₃ tend to be leached from the solum.