Tuesday, 8 November 2005
19

Reassessment of the Identification and Distribution of Vertisols in China.

Shanmei Wu, Nanjing Agricultural University/University of California, Berkeley, CA 94705, Xueming Yang, Agriculture & Agri-Food Canada, Harrow, ON N0R1G0, Canada, Xainzhou Long, Heilongjiang Water Conservancy and Hydropower Institute, Haerbing, 150080, China, and Paul Gersper, University of California at Berkeley, 145 Mulford Hall, Berkeley, CA 94720.

The concept of Vertisols, as a soil order, was first adapted in China in 1979 (Huang and Wu, 1979). The first map complied showing the distribution of Vertisols in China in 1982(Huang and Wu, 1982). More information and advances on Vertisols are available which enable us to reassess the identification and distribution.

Most China's Vertisols are derived from calcareous lacustrine deposits from different sources and ages. Some are developed on fine alluvium, basalt, and clay stone... They are usually occupted lowlands in valleys, on plains, on terraces..

Based on the Keys to Soil Taxonomy (USDA Soil Survey Staff, 2003). we found that the average clay content (%) is 52.93 ± 11.66 (n=201) throughout the pedon. The wedge-shaped aggregates occur average between 32 and 61 cm in depth from soil surface. Cracking (from 0.8 - 10 cm in width on soil surface) happens during dry seasons, and closing in summer - the monsoon season, or when irrigated. The soils have been cultivated for various crops and paddy rice, with different productivity.

The distributions are shown briefly below:

Aquerts (Caliaquerts, Endoaquerts, Halpoaquerts) are distributed in the north of Hui River, plains surrounding Shandong Peninsula, Nanyang basin, lake basins of Yangtze River, and other areas scattering in south and southwest China.

Cryerts (Humicryerts and Haplocryerts) are in Heilongjiang Province, the Northeast China.

Uderts (Haplouderts and Dystruderts) are distributed near the coast in subtropics and tropics in south China.

Usterts (Caliusterts and Haplousterts) are scattered in the southwestern Hainan Island, western Quangxi, and northern Yunnan. Those areas have ustic moisture regime caused by mountain relief. They are also found in north and west of Shandong Peninsula and Nanyang basin.

Torrerts (Calitorrerts) are also distributed in north Yunnan and northwest China.

A sketch soil map is complied showing the distribution of suborders of Vertisols in China.


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