黄土高原草地生产持续发展研究──Ⅰ．沙打旺人工草地衰退后的草种更替

Study on the Sustainable Development of the Grassland Production in Loess Plateau──I.Grass Varieties Alternation in the Declined Artifical Grassland of Astragalus adsurgens

沙打旺（Ａｓｔｒａｇａｌｕｓａｄｓｕｒｇｅｎｓ）人工草地通常生长数年后即自然衰退。由于沙打旺具有强烈的土壤干燥化作用，在衰退草地上播种深根性豆科牧草生长不良；而播种的浅根禾本科牧草则生长正常，这就为衰退后草地的特续发展提供了人工更新草种，并为在不宜农作的土地上建立永久人工草地打下了基础。

Artifical Astragalus adsurgens grassland usually declines naturally after some yearsof the gowth.In the declind grassland,long root legumes grasses don't grow well,but shortroot cereals grasses grow best,because Astragalus adsurgens has a strong soil-dryed action.These results can supply artifical alternating grass varieties for the sustainable development ofdeclined grassland,and form a basis for building permanent artifical grassland on unsuitablefarmland.