Soils of the Manas River Area in Northern Xinjiang,Peoples Republic of China

The Manas River Valley is situated in the centre of the continental landmass of Asia. The natural conditions in this region on the northern slope of the Tian Shan Mountains are characterized by an arid climate in an temperate geographical position (N 43°–46°, E 85°–87°), with extreme cold winters and high temperatures in summertime. The rivers, which are fed by glaciers, were formerly bordered by gallery forests (Tugais) along their main parts. There occurs an altitudinal sequence of soils but also a high variability within the same altitude due to changes of rocktype, relief, landuse and age of land surface. All the northern mountain slopes are mainly covered by loess deposits. The former forest-steppe Kastanozems and semidesert Xerosols are affected by severe erosion, which destroyed the former zonality there. In the transition zone to the desert, a quick change in the inclination, in the parent material (from loessial deposits to fine-textured alluvial quarternary deposits) and in the water supply (the groundwater rises up to the soil surface) take place. For this reason the Xerosol-Yermosol soil landscapes include soils like Gleysols, Solonchaks, Solonetz, Fluvisols and also Regosols. The great contrasts between winter and summer temperatures, the occurence of high temperatures when water supply is good and fine textured soils with high evaporation lead to the development of very fertile sites. They have a humusrich good structured topsoil, a favourable root penetrability and a high water capacity. On the other hand these soils are under natural and cultivated conditions affected by serious salinization in some parts of the area.