Abstract: The soil seed bank of the sandy meadow after 5 years enclosure of was studied. The results showed that the number of plant species was 38, among which, that of annuals and biennials,that of perennials and that of brushes was 24,9 and 5,respectively. The overall density of the soil seed bank was 13855?1651 grains穖^-2 ,among which, that of annuals and biennials was 96.58% of all the grains,87.20% was the annuol and biennial seeds of Artemisia scoparia,Chenopodium glaucum,Salsola collina,Setaria viridis and Eragrostis pilosa. Only 0.94% and 2.48% of the grains were those of perennials and brushes respectively. If divided into monocotyledoneae and dicotyledoneae, the number of seeds of the former accounted for 13.13% of that of total seeds while that of the later constituted 86.87%. The Leguminecae species comprised 2.83%. Regression indicated that the relationship between density of the soil seed bank and that of associated vegetation could be described by a cubic curve. The fenced sandy meadow vegetation would be in the stage of mixture of A. scoparia. et and forbs.

Key words: Nitrogen loss, Leaching, Pollution, Runoff, BMP practices