西辽河平原区免耕秸秆还田方式对土壤微生物群落组成的影响

Effects of No Tillage Straw Returning on Soil Microbial Community Composition in the West Liaohe Plain

【目的】针对干旱半干旱西辽河平原区农田耕层存在的土壤质量问题,揭示不同免耕秸秆还田方式对土壤微生物类群分布特征的影响。【方法】设置浅旋秸秆不还田农户模式(CK)、免耕秸秆秋覆还田(MG)、免耕秸秆秋覆春二次粉碎还田(ME)、免耕秸秆秋覆春配施秸秆腐熟剂还田(MF)、免耕秸秆秋覆春二次粉碎配施秸秆腐熟剂还田(EF)5个处理,用田间小区试验的方法,研究免耕和不同秸秆还田方式对土壤微生物群落组成的影响。【结果】0~15cm土层中4种免耕秸秆还田方式降低细菌操作分类单元数;15~30 cm土层中MF和EF细菌操作分类单元数较高,MF中增加节杆菌属(Arthrobacter)、芽单胞菌属(Gemmatimonas)和假平胞菌属(Sphingomonas)相对丰度,EF中增加Haliangium、溶杆菌属(Lysobacter)、Subgroup_10、Alistipes和拟杆菌属(Bacteroides)相对丰度;30~45 cm土层中4种秸秆还田方式均增加细菌操作分类单元数,增加了节杆菌属、拟杆菌属、Gaiella、硝化螺旋菌属(Nitrospira)相对丰度,但减少了Alistipes、Escherichia-shigella相对丰度。4种免耕秸秆还田方式降低0~15 cm土层真菌操作分类单元数,但增加15~45 cm土层真菌操作分类单元数;4种免耕秸秆还田方式降低了外瓶霉属(Exophiala)和被孢霉属(Mortierella)相对丰度,秸秆还田中新出现丝状真菌柄孢霉(Podospora)、角菌根菌属(Ceratobasidium)、Archaeorhizomyces,配施秸秆腐熟剂的2个处理新出现了粉褶蕈属(Entoloma),并增加了裂壳菌属(Schizothecium)的相对丰度。试验区能对生长环境产生较大影响的细菌比真菌多。从细菌多样性看,免耕秸秆秋覆春配施秸秆腐熟剂还田后增加了产黄菌属(Flavobacterium)、Ruminococcus__gnavus_group、Methylophilaceae相对丰度,ME和EF对产黄菌属和Methylophilaceae相对丰度增加幅度较大;从真菌多样性看,CK中Mrakia和Myceliophthora物种相对丰度较高,MF中Peristomialis和Powellomyces物种相对丰度较高,EF中Cercophora和Scytalidium物种相对丰度较高。【结论】免耕秸秆秋覆春二次粉碎还田及其施用腐熟剂措施可增加降解纤维素功能菌及菌根真菌多样性及相对丰度,对于西辽河平原雨养区春玉米田土壤微生物多样性、丰富度的提升具有积极作用。

[Objective]The distribution characteristics of soil microbial groups were revealed in arid and semi-arid areas,in order to provide theoretical support for the construction of the technology model of straw mulching and no tillage sowing in rain cultivation area of West Liaohe plain.[Method]Five treatments were set up:no-tillage with shallow rotation(CK),straw mulching in autumn and no-tillage in spring(MG),no-tillage with straw mulching in autumn and secondary crushing in spring(ME),no-tillage with straw mulching in autumn and application of saprophyte in spring(MF),and no-tillage with straw mulching in autumn and straw secondary crushing application of saprophyte in spring(EF),the effects of different ways of returning straw to soil on soil microorganism were studied.[Result]The results showed that the number of operational taxonomic unit(OTU)was decreased by returning straw to soil in 0-15 cm soil layer.The number of OTU of MF and EF bacteria in 15-30 cm soil layer was higher,the relative abundance rates of Arthrobacter,Gemmatimonas and Sphingomonas in MF was increased,the relative abundance rates of Haliangium,Lysobacter,Subgroup_10,Alistes and Bacteroides in EF were increased.The numbers of bacteria OTU,Arthrobacter,Bacteroidetes,Gaiella and Nitrispira were increased,but the relative abundance rates of Alistes and Escherichia-shigella were decreased in 30-45 cm soil layer.Straw returning reduced the number of soil fungi OTU in surface soil(0-15 cm),but increased the number of OTU in 15-45 cm soil.Straw returning reduced the relative abundance rates of Exophiala and Mortierella.Podospora,Ceratobasidium and Archaeorhizomyces appeared in straw returning.Entoloma and Schizomyceum appeared in the application of ripening agent,and increased the relative abundance rates of Schizomyceum.There were more bacteria than fungi that could have a great impact on the environment in the test area.In terms of bacterial diversity,the relative abundance rates of Flavobacterium,Ruminococcus_gnavus_group,Methylophilaceae were increased after no tillage returned straw to the field and decomposition agent.ME and EF increased the relative abundance rates of Flavobacterium and Methylophilaceae significantly.In terms of fungal diversity,the relative abundance rate of Mrakia and Myceliophthera in CK was higher,the relative abundance rates of Peristomalis and Powellomyces in MF was higher,and the relative abundance rates of Cercophora and Scytalidium species in EF was higher.[Conclusion]The patterns of no-tillage straw returning to the field in autumn and spring with secondary crushing and application of decomposing agents can increase the diversity and relative abundance of cellulose-degrading functional bacteria and mycorrhizal fungi,which plays a positive role in improving the soil microbial diversity and richness of spring maize field in the rain-fed area of West Liaohe plain.