山药连作对土壤微生物群落及土壤酶活性的影响

Effect of Chinese Yam Continuous Cropping on the Soil Microbial Community and Soil Enzyme Activity

以山药连作(0a,1a,2a)和轮作(山药—小麦)土壤为研究对象,探讨耕作模式对山药种植地耕层土壤(0—30cm)微生物数量和酶活性的影响。结果表明:土壤耕层的有机质、全氮、有效磷和速效钾含量随山药连作年限的延长而逐渐降低,而山药—小麦轮作模式则有助于恢复地力。山药连作、轮作的土壤均以细菌所占比例最大,放线菌次之,真菌最少;与对照(0a)相比,细菌、放线菌数量均随着山药连作年限增加呈递减趋势;但放线菌的降幅明显大于细菌,表现出对连作年限更强的敏感性;真菌数量随连作年限呈先升后降的趋势。山药连作可以明显降低土壤脲酶、碱性磷酸酶和蔗糖酶的活性,轮作模式则可以激发该三种酶的活性,其中轮作较连作2a的处理可以明显提高脲酶和蔗糖酶活性,差异分别达显著水平(p<0.05)和极显著水平(p<0.01)。说明山药连作会破坏土壤耕层微生物种群结构,并抑制土壤酶活性,轮作可以在一定程度上改善土壤微生物群落结构及酶活性质量。

With regard to the soils grown yam for different continuous planting years （0 year, 1 year, 2 years） and different rotation system （yam wheat）, we examined the microbial communities and enzyme activities of soils（0 30 cm） of different tillage patterns. The results showed that： the contents of soil organic matter, total nitrogen, phosphorus and potassium gradually decreased with the increase of yam cropping years, while the yam-wheat rotation mode helped to restore the soil fertility; bacteria was the largest, followed by actino- mycetes, fungi was the least in each treatments; compared with the control, bacteria, actinomycetes showed a decreasing trend with increase of yam cropping years. The decline of actinomycetes was significantly greater than that of bacteria, which showed actinomycetes was more sensitive than bacteria with continuous cropping. The quantity of fungi increased at first and then decreased. Continuous cropping can significantly reduce the soil urease, alkaline phosphatase and invertase activity, while the rotation mode can stimulate the activity of the three enzymes. The activities of soil urease and invertase of rotation treatment were significantly higher than those of continuous cropping 2 years of treatment, and the difference was significant （p〈0.05） and extremely significant（p〈0.01）, respectively. The study results imply that the continuous cropping will destroy the soil microbial community structure and restrain soil enzyme activity, and the crop rotation can improve soil quality to a certain extent.