Abstract: In this study,two shrubby species Caragana korshinskii Kom. and Zygophyllum xanthoxylon (Bunge) Maxim.and two herbaceous species Agropyron trachycaulum and Medicago sativa L.adaptive to the natural conditions in the Xining Basin were screened out to experimentally plant in the Changling Gully in the basin.In the research area,the four species were planted by means of single planting and assembled planting.The contents and variations of eight soluble salts including K⁺,Ca²⁺,Na⁺,Mg²⁺,SO^2-₄,Cl^-,HCO^-₃ and CO^2-₃ in different soil layers and plant stems and roots under the two different planting conditions were discussed.The capabilities of two herbaceous and two shrubby species in reducing total salt content in slope soil were evaluated.The test results revealed that,under single planting of these four species,their effect in reducing the contents of SO^2-₄,Ca²⁺ and Na⁺ was significant,and that of herbaceous and shrubby assemblage Ⅰ (C.korshinskii + M.sativa + A.trachycaulum) and assemblage II (Z.xanthoxylon + M.sativa + A.trachycaulum) in reducing the contents of SO^2-₄,Ca²⁺,Mg²⁺,K⁺ and Na⁺ in slope soil was significant.The salt reduction effect of M.sativa was relatively more significant,and then that of C.korshinskii and A.trachycaulu,but that of Z.xanthoxylon was not significant.The salt reduction effect of the herbaceous and shrubby assemblage II was significantly higher than that of the herbaceous and shrubby assemblage I.

Key words: soil salt reduction, soluble salt ion, total salt content, single planting, herbaceous and shrubby assemblage, Xining Basin