30年不同设施条件和栽培方式下土壤养分和微生物群落功能多样性的变化

Changes of soil nutrients and microbial community diversity in responses to different growth environments and cultivation practices in 30 years

【目的】随着设施蔬菜栽培年限的增加设施连作土壤生态环境发生很大变化。系统研究长期不同设施类型和栽培方式下土壤养分和微生物群落多样性的变化,可为蔬菜土壤可持续利用提供理论依据。【方法】选择连续30年以不同设施进行蔬菜栽培的土壤(1969~2009年)进行田间试验。以温室连作两茬黄瓜、夏季休闲为对照(CK);温室连作两茬黄瓜夏季填闲毛豆/花生(CS_1);大棚连续种植两茬黄瓜(CS_2);大棚前28年连作黄瓜、后两年露地种植绿叶菜(CS_3);连年露地种植绿叶菜(CS4)5种种植方式。于2009年采集0-20 cm土壤样品,采用常规方法系统分析了土壤养分含量和微生物数量,对培养96h、120 h和144 h的AWCD值进行主成分分析(principal component analysis,PCA)、六大碳源利用程度及Shannon-Weaver指数多样性指数分析。【结果】CS_1处理每孔平均颜色变化率(AWCD)显著高于其他处理;在96、120、144 h主成分分析表明,第1主成分分别解释了32.9%、33.61%和32.21%的碳源利用差异,CK处理在主成分1上均与其他处理显著分开,第2主成分分别解释了14.2%、15.96%和16.42%的碳源利用差异,CK处理在96和144 h与其他处理显著分开;在主成分1主成分3加权上96 h与144 h的CS_3、CS_4和CS_1处理显著不同于CK和CS,处理。96、120和144 h主成分1差异的贡献碳源主要是氨基酸、羧酸类化合物主成分2差异的贡献碳源主要是胺类化合物、多聚物。各处理对六大碳源利用显著不同,CK和CS,处理对碳水化合物、羧酸类化合物和多聚物利用显著低于其他处理。CK和CS,处理微生物群落多样性指数和均匀度指数均显著低于其他处理;CS3和CS4处理细菌数/真菌数比(B/F)以及微生物总量均高于其他处理分别显著高于对照310.34%、334.48%和280.1%、368.0%;CK处理全氮、有机质、速效钾和硝态氮显著高于其他处理,CS、处理相对CK处理则显著降低其含量,其中全氮、有机质、速效钾、铵态氮和硝态氮含量分别显著降低41.46%、50.26%、51.47%、26.72%和54.11%,CS_3和CS_4处理全氮、速效磷、速效钾、硝态氮均显著低于其他处理。全氮、速效养分均与B/F、微生物总量、微生物多样性指数呈负相关,铵态氮与其均呈极显著负相关速效磷与B/F、微生物总量呈极显著负相关。【结论】30年温室连作黄瓜土壤养分累积严重,夏季填闲毛豆/花生可显著降低硝态氮累积和增加微生物多样性;30年温室大棚单—连作黄瓜显著降低微生物群落多样性;30年露地种植绿叶菜以及大棚后两年露地种植叶菜的微生物数量均较高且养分累积最低。

[Objectives]With the elongation of vegetable cultivation,the soil bio-ecosystems will change greatly.Systematically research on the changes in soil nutrient availabilities and the microbial community will provide theoretical support for the sustainable vegetable production.[Methods]The soils consecutively used for vegetable production over 30-years under different growth environments and cultivation practices were chosen for the investigation.Double cucumber cropping followed by fallow in summer in greenhouse was used as control（CK）,double cucumber followed by green soybean/peanut in summer（CS1）,double cucumber cropping in plastics greenhouse（CS2）,double cucumber in plastics greenhouse for the first 28 years and followed by two-years＇ green leafy vegetables in open filed（CS3）,and consecutive green leafy vegetables in the open filed（CS4） were used.The soil samples of 0-20 cm depth were collected in 2009,and the soil nutrient contents and microbial quantity were measured with conventional methods.The microbial community diversity was evaluated with the values of Average Well Color Development（AWCD）,the utilization of six C sources with the principal component analysis（PCA）.[Results]The AWCD values of CS1 was significantly higher than other treatments.Differences of carbon resources utilization were 32.9%,33.61%and 32.21%,respectively at 96 h,120 h and 144 h in principal component 1,and the CK was significantly different from others in principal component 1.The differences in carbon resources utilization were 14.2%,15.96%and 16.42%at 96 h,120 h and 144 h separately in principal component 2,and the CK was significantly different from the others at 96 h and 144 h.According to the weights of principal component 1 to 3,CS1,CS3 and CS4 had differences with CK and CS2at 96 h and 144 h,respectively.The main carbon resources contributing to the difference in principal component 1 were amino acids,carboxylic,amine compounds,amino acids,and to the difference in PC2 were amines and polymers.The utilization of the six carbon sources was significantly different among the treatments.The utilization values of carboxylic acids,carbohydrate and polymers of CK and CS2were lower than those in other treatments.Both microbial community diversity and evenness in CK and CS2were significantly lower than those in other treatments.The ratio of bacteria/fungi（B/F） and the microbe quantity of CS3 and CS4 were significantly higher than those in other treatments.Compared with CK,the B/F value and microbe quantity of CS2 and CS4 were increased by 310.34%,334.48%and 280.1%,368.0%,respectively.The total N,available K,organic matter and NO3-N in CK were higher than those in other treatments,Compared with CK,CS1 reduced the accumulation of total N,organic matter,available K,NO3~1-N,NH4~＋-N by 41.46%,50.26%,51.47%,26.72%and 54.11%separately.The total N,available P,available K and NO3^--N CS3 and CS4 were lower than those in other treatments.The total N and available nutrient had negative correlation with B/F,microbial quantity and microbial community diversity,and NH4~＋-N had significant negative correlation.[Conclusions]The continuous cropping of cucumber followed by fallow in summer in greenhouse for 30 years accumulates a lot of nutrients in soils,followed by green soybean and peanut increases the microbial diversity and reduces NO3^--N contents.Continuously cropping of cucumber for 30 years in greenhouse has reduced the microbe community diversity.The consecutive cultivation of green leafy vegetables in open field for 30 years and in plastic greenhouse for 2 years improve the microbe quantity and reduce available nutrient contents in soils.