种植年限和种植模式对设施土壤微生物区系和酶活性的影响

Soil Microbial Community and Enzyme Activities in Greenhouse with Different Cultivation Years and Planting System

为探讨大棚种植年限和不同种植模式对土壤质量的影响,分析土壤质量退化的原因,对昆明郊区蔬菜、花卉主产县典型大棚土壤进行取样,分析测定了土壤微生物区系和酶活性的变化。结果表明,随设施种植年限的增加,土壤细菌、放线菌、微生物总数、B/F比值及土壤过氧化氢酶、脲酶和蔗糖酶活性先增加后降低,以种植6～8a时最高而20a时最低;真菌数量持续增加而微生物多样性指数和均匀度指数持续降低。与连作相比,轮作有利于增加土壤细菌、放线菌数量而降低真菌数量,有利于提高过氧化氢酶、脲酶和蔗糖酶活性,其中花-花轮作效果最好,菜-菜轮作效果最差。研究结果表明大棚种植初期(4～6a)土壤生态环境较好,6～8a后土壤微生物区系失调,酶活性显著下降,从而影响土壤生物化学过程,土壤质量的稳定性和可持续利用性大大降低;轮作种植能有效调节土壤微生物区系,有利于微生物群落多样性和稳定性的提高,有利于土壤质量的改善。

Soil microbial community and enzyme activities of selected protected soils in Kunming suburb were determined for illustrating the effects of cultivation years and cropping system on soil quality and soil quality degradation. Results showed that the amount of bacteria, actinomyces, total microbe and B/F as well as catalase, urease, sucrase activities of soils increased in the beginning （4-6 years） and then decreased with the cultivation years, the peak of those were observed with 6-8 years protected soils and the lowest were with 20 years protected soils. The amount of fungi continuing increased and the Shannon-Wiener diversity index, Simpson diversity index continuing decreased with the cultivation years. In relation with crop rotation, flower-flower crop rotation system was most beneficial for increasing the amount of bacteria and actinomyces and catalase, urease, sucrase activities of protected soils; Vegetable-vegetable crop rotation system was the least beneficial for increasing those of protected soils. Results indicated that in the early years of cultivation （4-6 years ）, the quality of protected soils were good, but after 6-8 years cultivation, the soil microbial flora gradually become imbalanced, enzyme activities decreased, and soil quality and productivity deteriorated. Crop rotation practice could regulate soil microbial flora and improve diversity and stability of microbial community and soil quality.