不同年限玉米秸秆还田对土壤微生物多样性的影响

Effects of maize straw returning for different years on soil microbial diversity

秸秆还田是培肥地力、改良土壤的重要措施。内蒙古高原向松辽平原过渡地带春玉米区,玉米长期连作导致了耕层变薄、土壤次生盐渍化等土壤退化问题。采用田间定位试验的方法,研究连续多年(8、5、2年)秸秆旋耕还田条件下对土壤微生物的影响。结果表明,秸秆还田土壤中最丰富的细菌类型为变形菌门(Proteobacteria),其次为放线菌门(Actinobacteria)、芽单胞菌门(Gemmatimonadetes)、拟杆菌门(Bacteroidetes);真菌类型为子囊菌门(Ascomycota)和担子菌门(Basidiomycota)。随着秸秆还田年限的增加,变形菌门和酸杆菌门(Acidobacteria)相对丰度增加、放线菌门相对丰度下降,拟杆菌门相对丰度较稳定;子囊菌门、担子菌门、接合菌门(Zygomycota)相对丰度先下降后上升,而球囊菌门(Glomeromycota)和壶菌门(Chytridiomycota)相对丰度变化规律相反;属水平上Sphingomonas、Lysobacter、Hannaella相对丰度先上升后下降,而Leptosphaeria和Monodictys相对丰度变化规律相反;Pseudarthrobacter、Fusarium相对丰度下降,Gaiella相对丰度较稳定;Guehomyces相对丰度增加;并且细菌和真菌相对丰度拐点均出现在秸秆还田5年后。随着秸秆还田年限的增加,土壤细菌和真菌多样性均有所降低;秸秆还田与秸秆不还田土壤的差异物种有Aquicella、Fusicolla和Spizellomyces;由此可推测,秸秆还田增加土壤氮和钾含量,减少病害;试验区连续多年的玉米秸秆还田改变了土壤微生物群落组成,玉米秸秆连续还田5年后土壤微生物多样性有下降趋势。

Straw returning is an important measure to improve soil fertility.Aiming at the problems of soil degradation,such as thinning of cultivated layer and secondary salinization of soil,in the spring corn area in the transition zone from the Inner Mongolia Plateau to the Songliao Plain,under the condition of long-term continuous cropping of corn,used the method of field positioning test to study the effects on soil microorganisms under the condition of returning straw with rotary tillage to the field for different consecutive years(8,5,2 years).The results showed that Proteobacteria was the most abundant bacteria in straw returning soil,followed by Actinobacteria,Gemmatimonadetes and Bacteroidetes.The types of fungi were Ascomycota and Basidiomycota.With the increase of straw returning years,the relative abundance of Proteobacteria and Acidobacteria were increased,the relative abundance of Actinobacteria was decreased,while the relative abundance of Bacteroidetes was relatively stable.The relative abundance of Ascomycota,Basidiomycota and Zygomycota were decreased first and then increased,while the relative abundance of Glomeromycota and Chytridiomycota was opposite.At the genus level,the relative abundance of Sphingomonas,Lysobacter and Hannaella were increased first and then decreased,while the relative abundance of Leptocephalia and Monodictys had opposite changes.The relative abundance of Pseudomonas and Fusarium were decreased,and the relative abundance of Gaiella was relatively stable.The relative abundance of Guehomyces was increased.The inflection point of relative abundance of bacteria and fungi occurred 5 years after straw returning.With the increase of straw returning years,the diversity of soil bacteria and fungi were decreased.The difference species of soil between straw returning and straw not returning are Aquicella,Fusicolla and Spizellomyces.It can be speculated that straw returning can increase the content of soil nitrogen and potassium,and reduce the disease.The soil microbial composition was changed after corn straw returning for many years,and the soil microbial diversity decreased after corn straw returning for 5 years.