不同耕作方式对土壤酶活性及微生物量和群落组成关系的影响

Effects of different tillage methods on soil enzyme activity,microbial biomass and community composition

【目的】明确土默川平原灌区短期不同耕作方式下土壤酶活性、微生物数量和群落组成的差异性,为该区域耕作方式的合理使用提供理论依据。【方法】试验采用大区设计,设置免耕(NT)、深翻(DP)、深松(SS)、条深旋(SC)和农户浅旋(CK)5种耕作方式,分析土壤酶活性、微生物数量、微生物量碳、微生物量氮的差异性;采用16S rRNA扩增子测序方法,明确土壤微生物群落结构组成。【结果】DP和SS处理对土壤微生物数量、微生物量碳、微生物量氮和土壤酶活性的提高有显著影响,且年际间差异显著(P<0.05)。不同耕作方式土壤细菌群落组成较为相似,但物种丰度存在显著差异(P<0.05),主要以Actinobactera、Proteobacteria、Chloroflexi和Acidobacteria等菌门组成,其中DP处理土壤优势细菌门中以Actinobactera、Chloroflexi、Acidobacteria等菌门最丰富;SS处理优势细菌属主要以RB41、Bacillus、Sphingomonas、Rubrobacter等菌属最丰富。DP和SS处理显著提高土壤过氧化氢酶、蔗糖酶、蛋白酶活性和细菌数量、微生物量碳含量、微生物量氮含量,使得Chloroflexi、Firmicutes、Planctomycetes等菌门和RB41、Nordella、Bacillus、Sphingomona等菌属增加,促进物质循环;CK处理土壤细菌群落对生物学指标的变化表现不敏感;NT处理使得Actinobactera菌门和Gaiella、MND1菌属增加;SC处理使得Gemmatimonadetes菌门和Sphingomonas菌属增加。【结论】深松和深翻处理在一定程度上均可以显著增加土壤酶活性、微生物量和微生物群落组成,进而提高土壤质量,其中,深松处理提高效果最为显著,深翻处理次之。

【Objective】To clarify the differences in soil enzyme activity,microbial quantity and community composition under different short-term tillage methods in the irrigation area of Tumedchuan Plain,and provide a theoretical basis for the rational use of tillage methods in this region.【Methods】The experimentation adopted the regional design;five tillage measures including no tillage(NT),deep ploughing(DP),subsoiling(SS),strip deep rotation(SC)and farmer shallow rotation(CK)were set up;and the differences of soil enzyme activity,microbial quantity,microbial biomass carbon and microbial biomass nitrogen were analyzed;16S rRNA extender sequencing method was used to explore the microbial community composition.【Results】DP and SS treatments had significant effects on the increase of soil microbial quantity,microbial biomass carbon,microbial biomass nitrogen and soil enzyme activity,and the difference was significant between years(P<0.05).The composition of soil bacterial community under different tillage methods was similar,but there were significant differences in species abundance(P<0.05),mainly reflected in Actinobactera,Proteobacteria,Chloroflex and Acidobacteria.Among them,Actinobactera,Chloroflexi and Acidobacteria were the most abundant bacteria in the soil dominant bacteria phyla under DP treatment,and RB41,Bacillus,Sphingomonas and Rubrobacter were the most abundant bacteria genus in SS treatment.DP and SS treatments significantly increased soil catalase activity,sucrase activity,protease activity,microbial quantity,microbial biomass carbon content,and microbial biomass nitrogen content,making Chloroflexi,Firmicutes and Planctomycetes and other bacteria genus such as RB41,Nordella,Bacillus,and Sphingomona increase,promoted material circulation;CK treatment of soil bacterial communities was not sensitive to changes in biological indicators;NT treatment increased Actinobactera and Gaiella,MND1;SC treatment increased Gemmatimonadetes and Sphingomonas.【Conclusion】Both subsoiling treatment and deep plowing treatments could significantly increase soil enzyme activity,microbial biomass and microbial community composition,and then improve soil quality.Among them,subsoiling treatment had the most significant effect,followed by deep plowing treatment.