【摘要】 以不同砂龄(砂田覆盖年限分别为1、6、12、19 a和25 a)的砂田为研究对象,对砂田土壤混合层、根系密集层、淋溶层和钙积层的土壤微生物区系及影响土壤微生物的因素进行研究。结果表明:(1)砂田土壤微生物组成中,以细菌为主,放线菌次之,真菌最少;随土壤剖面深度的增加,土壤微生物总数迅速减少,这主要是由于细菌数量迅速减少所致;受根系分布的影响,根系密集层的微生物数量高于只有少量根系分布的混合层。(2)细菌和放线菌的数量在作物生长期高于作物非生长期,而真菌的数量则相反。(3)细菌和真菌在砂龄约为6~12 a的砂田中最多,随砂田覆盖时间的增加,砂田逐渐老化,数量逐渐减少;而放线菌的数量反之,在砂龄约为6~12 a的砂田中最少,随砂田覆盖时间的增加而增加。(4)砂田土壤微生物数量与土壤水分含量、pH值和覆盖时间有很好的相关性,土壤养分中的全C含量是限制砂田土壤微生物数量的重要因子。更多还原

【Abstract】 Soil microflora and physicochemical properties at soil and gravel-sand mixed layer( SGSML),roots denseness layer( RDL),eluvial layer( EL) and Calcic horizon layer( CAL) in gravel-sand mulched field( GSMF) with different gravel mulched years( 1,6,12,19 a and 25 a respectively) were investigated. The results indicated that( 1) Among the soil microorganisms of the GSMF,bacteria population was greatest,actinomycete was followed,and fungi was the least one. As the deeper of the soil profile,the soil microorganisms population was decreased rapidly that mainly result from rapidly decreasing of bacteria population. Soil microbial population in RDL was greater compared with that of SGSML with fewer roots due to effect of different crop roots distribution.( 2)Population of bacteria and actinomycete in crop growth period was greater than that of the fallow season,while the fungi population in crop growth period was lower than that of the fallow season.( 3) Bacteria and fungi population reached the maximum number when the gravel mulched with 6 a to 12 a. Bacteria and fungi population was decreased as increasing of gravel mulched years due to gradually aging of GSMF. The actinomycete population was the other way round.( 4) Good correlation was found between soil microbial population of GSMF and soil water content,pH,gravel mulched years. Soil total C content was one of the important factors restricting the soil microbial developing.更多还原