Abstract: In order to explore the causes of continuous cropping obstacles in garlic, this paper selected the soils in which garlic was grown for 0 year (control), 5 years, and 10 years as research objects, and researched the changes of soils nutrients, soil microorganism quantity and enzyme activities. The results showed that with the increasing of continuous cropping years, garlic yield dropped significantly compared with the control. The production decreased by 31.1% and 40.8% in 5 years and 10 years of continuous cropping soil, respectively. Soil pH increased significantly, while soil available potassium, ammonium nitrogen, nitrate nitrogen and soil organic matter decreased under long-term continuous cropping. The quantity of bacteria and actinomyces decreased, while that of fungi increased．The activities of urease, saccharase and catalase in soil tended to be decreased within 10 years of continuous cropping, indicating that long-term continuous cropping altered the soil nutrient. In conclusion, after long-term continuous cropping, the yield of garlic and enzyme activity decreased, soil pH increased, and the microorganism composition and structure were altered. It is suggested that organic fertilizer was applied to improve the enzyme activity and balance the soil microbial community structure soil property.

Key words: garlic, continuous cropping, soil microorganism, soil enzyme activity, nutrient transformation

摘要： 为探讨引起大蒜连作障碍形成的原因，研究了连作0年（对照）、5年和10年的大蒜土壤理化性质、土壤微生物数量和酶活变化趋势。结果表明，随着连作年限的增加，大蒜产量降低，与对照相比，连作5年和10年的大蒜产量分别下降了31.1%和40.8%。大蒜连作使土壤pH升高，土壤速效钾、铵态氮，硝态氮及有机质的含量降低；土壤中细菌、放线菌数量降低，而真菌数量升高；土壤中过氧化氢酶、脲酶和蔗糖酶活性显著降低，说明长期连作影响土壤中物质和养分的转化。综上所述，长期连作使大蒜产量降低，pH升高，酶活降低，土壤中微生物结构发生改变。建议施用有机肥来改善土壤性质，改良土壤中微生物的酶活性和菌群结构。

关键词: 大蒜, 连作, 土壤微生物, 土壤酶活, 养分转化