乌兰布和沙漠东北缘三种豆科绿肥植物生物量和养分含量及其对土壤肥力的影响

土壤肥力是限制乌兰布和沙漠东北缘沿黄灌区建立高产绿洲的主要因子之一。在内蒙古自治区磴口县试验地种植3种绿肥植物，比较它们改良土壤的效果。结果表明，1～2年生紫花苜蓿的总生物量干重为最高，而沙打旺则因其抗风沙能力强，地上部分生长较其它两种植物为好，由于植株中水分含量较高，其生物量的鲜重在三者中是最高的。2年生绿肥植物总生物量干重和养分含量的测定结果则显示，全氮和全磷含量的变化趋势为沙打旺〉紫花苜蓿〉草木樨，而全钾含量则为紫花苜蓿〉草木樨〉沙打旺；从3种植物对土壤改良效果来看，改良作用为沙打旺〉紫花苜蓿〉草木樨。与两种常用的绿肥作物相比，沙打旺因其对风沙较强的抗性而具有较高的改良土壤能力，因此在同类型的沙漠绿洲开发初期可以作为改良土壤的首选植物。

Biomass and nutrient concentrations of three green manure leguminous plants and their effects on soil nutrients at northeastern edge of Ulanbuhe Desert

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.