Abstract: Soil fertility is one of the main factors limiting the establishment of cost-effective oasis along the Yellow River irrigated area at northeastern edge of Ulanbuhe Desert.The study on the soil improvement with three leguminous plants in the experimental site of Dengkou County,Inner Mongolia showed that among three test green manure plants,1-and 2-year-old Medicago sativa had the highest total dry biomass,while Astragalus adsurgens,one of typical psammophytes,had the highest above-ground fresh biomass and plant water content due to its high ability against blown-sand damage.The total N and P concentrations of plants were in order of Astragalus adsurgens>Medicago sativa>Melilotus suaveolens,whereas the total K concentration was Medicago sativa>Melilotus suaveolens>Astragalus adsurgens.Astragalus adsurgens was the most suitable used as green manure,followed by Medicago sativa,and Melilotus suaveolens.The soil improvement effect of these three plants was also in the order of Astragalus adsurgens>Medicago sativa>Melilotus suaveolens.Comparing with other two commonly used green manure leguminous plants,Astragalus adsurgens had a better soil improvement feature in arid oasis due to its resistance to blown-sand,and could be the preferred plant for soil improvement in the early stage of desert development.

Key words: Chromium, Daphnia carinata, Phototactic behavior, Biomonitor