Abstract:

A field experiment was conducted to study the seasonal variations of soil enzyme (urease and catalase) activities in alfalfa field with different growing years (1~5 years) in Horqin sandland, and the objective was to provide a theoretical basis for the alfalfa field management. Results indicated that the two kinds of soil enzyme activities decreased significantly with the increase in soil depth,the most active in the 0~20 cm depth, and showed the surface gathering vertical distribution characters. the two kinds of soil enzyme activities increased at first and then decreased with the increase of growing years. In the 0~70 cm depth, the catalase-enzyme activity was 2 a > 5 a > 4 a > 1 a > 3 a and urea-enzyme activity was 2 a > 5 a > 3 a > 4 a > 1 a> CK(primary vegetation land). The catalase-enzyme activity of rhizosphere soil in 2-year-old alfalfa field was much higher than that in 1-year-old and 3~5 year-old alfalfa fields(P<0.05). The catalase-enzyme activity of non-rhizosphere soil in 2-year-old and 4~5 year-old alfalfa fields was much higher than that in 1-year-old and 3 year-old alfalfa field (P<0.05). The catalase-enzyme activity of rhizosphere soil was much higher than that of non-rhizosphere soil in different growing years, and showed significant difference between rhizosphere soil and non-rhizosphere soil from first year to third year of alfalfa growth.

Key words: Alfalfa, Growing years, Soil enzyme activity, Soil depth, Horqin sandy land

摘要：

在科尔沁沙地大田试验条件下，研究了不同种植年限（1~5 a）苜蓿草地土壤脲酶和过氧化氢酶活性的时（年限）空（土层）变化特征，旨在探讨种植不同年限苜蓿对土壤生物化学性状的影响，为沙地苜蓿草地管理提供科学依据。结果表明：2种土壤酶活性都随着土层加深而降低，0~20 cm 土层，土壤酶活性最强，呈现出表聚性。随着种植年限增加，2种土壤酶活性都呈先增后降趋势。在0~70 cm土层，土壤过氧化氢酶活性大小顺序为：2 a > 5 a > 4 a > 1 a > 3 a；土壤脲酶活性大小顺序为：2 a > 5 a > 3 a > 4 a > 1 a > 原生植被地。2年龄苜蓿草地根际土过氧化氢酶活性显著高于1年龄和3~5年龄（P<0.05）；2年龄和4~5年龄苜蓿草地非根际土过氧化氢酶活性显著高于1年龄和3年龄（P<0.05）。不同种植年限苜蓿草地根际土过氧化氢酶活性均高于非根际土，其中，种植第1年至第3年土壤酶活性差异显著（P<0.05）。

关键词: 紫花苜蓿地, 种植年限, 土壤酶活性, 土层深度, 科尔沁沙地