Abstract: A study comparing the soil of a plot of grassland transformed from cropland with that of a wheat-field in the agro-pastoral transitional zone reveals that the content of amylase and of urease in a soil depth of (0～20) cm of the former are higher than those of the latter of the same soil depth.Land cultivated with wheatgrass or smooth bromegrass is enriched with high amylase or urease content. Mixed sowing of Siberian wildrye and wheatgrass(1∶3) could raise the soil content of amylase, while Siberian wildrye and wheatgrass sowed in a ratio of 1∶1 could raise the soil content of urease effectively. However, With prolonged utilization of the land for cultivating the Siberian wildrye, the amylse and urease contents in the soil instead of increasing reduce with the passing of time.

Key words: Agro-pastoral transitional zone, Transforming cropland into grassland, Amylase, Urease

摘要： 在农牧交错带以小麦为对照,研究退耕还草对0～20cm土壤淀粉酶和脲酶活性的影响.结果表明:退耕还草后,草地土壤淀粉酶和脲酶活性都显著高于小麦地;冰草和无芒雀麦草地土壤淀粉酶活性和脲酶活性最高;老芒麦+冰草(1∶3)对改善土壤淀粉酶的效果较好;老芒麦+冰草(1∶1)提高土壤脲酶活性的作用较大;随着利用年限的增加,老芒麦草地土壤淀粉酶活性和脲酶活性均呈先增加,后降低的趋势.

关键词: 农牧交错带, 退耕还草, 淀粉酶, 脲酶