Effect of different land utilization on soil nutrient and soil enzyme in Loess Plateau

chinois. 为了研究吴旗县不同土地利用方式对土壤养分以及酶活性的影响，对农耕地、天然草地、人工草地、灌木林地和乔木林地5种土地利用方式的土壤进行了调查、样品测定和分析。结果表明，天然草地和乔木林地0~20 cm表层土壤有机质增长率均较大，为36.11%和32.96%，二者碱解氮含量也较高，分别为66.88和69.37 mg/kg；乔木林地和灌木林地0~20 cm表层土壤有效磷含量均高于天然草地和人工草地，乔木林地速效钾含量最高。乔木林地0~20 cm土层土壤脲酶、碱性磷酸酶和蔗糖酶3种水解酶活性均高于其他4种土地利用方式，0~20 cm土层土壤酶活性均高于20~40 cm土层，表明人工种植乔木林可以使土壤水解酶活性增强，尤其表现在表层土壤。总之，乔木林对土壤有机质和养分、酶活性的增强效应最为明显。

anglais. To study the effects of different land utilization on soil fertility and enzyme activity in Wuqi county, the research was designed to deal with the different land utilization by the survey of the soil vegetation, the sample test and the indoor analysis. The results indicated that the content of organic matter of the natural meadow and the arbor forest land in the 0-20 cm surface soil grew separately by 36.11% and 32.96%; the nitrogen content of the natural meadow and the arbor forest land was also high, being 66.88 mg/kg and 69.37 mg/kg, respectively; the content of fast-acting potassium in the surface soil was higher than that of meadow, while the activity of the urea enzyme, alkaline phosphatese and sucrase of the arbor forest land was stronger than that of the other four land utilization modes. Enzyme activities in 0-20 cm layer were stronger than those in the 20-40 cm layer, which showed that the manual-planted arbor forest could make the soil hydrolytic enzyme activities strong, especially in the surface layer. In short, the arbor forest land could enhance soil organic matter, nutrients and enzyme activities significantly.