| Irrigation is a main agricultural management measure in arid regions.The area of irrigated farmland has reached 61.67 million hectares in China,and the area of water-saving irrigation has reached 27.13 million hectares with the development of sustainable agriculture.However,furrow irrigation is still widely used,especially in vegetable fields,which require multiple water sources.This results in the waste of water and issues relating to soil quality.Recent studies have demonstrated that irrigation can change the soil moisture conditions,and thus affect soil microbial.Soil microbial,a significant assessment index for soil quality.Therefore,determining soil microbial diversity is important for the evaluation irrigation methord.The objective of this study was to analyze the effects of different irrigation methods on soil microbial,which wad assessed by microcalorimetric,quantitative PCR,Illumina HiSeq sequencing technology and DNA-SIP methods,based on a long-term irrigation experiment in Shenyang Agriculture University.Three irrigation methods were investigated,including drip irrigation(DI),surface drip irrigation(SDI),and furrow irrigation as a control.The main research results are as follows:(1)There was no significant difference in soil enzyme activity or soil respiration under different irrigation systems.Compared with conventional methods,the microcalorimetric method provided more useful information on changes in the soil microbial activity.The microcalorimetric method produced a power-time curve,which was a typical microbial growth curve.Based on the soil thermal dynamic index,changes in total heat,maximum thermal power,and growth rate under DI and Control were negligible;however,activity was the lowest with SDI.Furthermore,the microcalorimetric method represents a novel way of detecting microbial activity,which was difficult to detect using traditional methods.As a consequence,the use of traditional methods to determinate soil microbial activity is limited,and the microcalorimetric method is highly sensitive for the determination of soil microorganism activity.(2)Applied Illumina HiSeq sequencing technology study soil bacterial community structure diversity under different irrigation systems,the dominant bacteria were Proteobacteria,Actinomyces and Acidobacteria.Compared with control,DI has less effect on bacterial community and diversity.DI has more benefical proteobacteria and actinomyces than Control.18S rDNA gene copy number of DI was the highest.The dominant fungal were Ascomycetes,Basidiomycetes and Zygomycota,DI and SDI hsd a higher abundance of zygomycosis and less amount of Basidiomycetes,Mortierellales and Trechisporale than Control.Fungal diversity of water-saving irrigation was higher than Control,and there were some beneficial fungi.Biolog technology research soil carbon source using ability under three irrigation methods,DI and Control has similar diversity index,and carbon source was given priority to acids,sugars and amino acids,and SDI was priority to use sugars.(3)Combined DNA-based stable isotope probing with cloning sequencing technology to study effect of different irrigation systems on ammoxidation.In the process of cultivation,nitrification of three irrigation soil sample was significantly increased,ammonia oxidizing bacteria amoA gene was significantly labbled by 13C in heavy layers of DNA.But ammonia oxidizing archaea amoA gene was not detected in layered DNA.By AOB phylogenetic tree,all AOB was belong to the Nitrosospira-like,Nitrosospira.As a result,ammonia oxidizing bacteria may be dominating the soil nitrification under different irrigation systems.Therefore,drip irrigation with plastic was the method of water-saving irrigation most suitable for maintaining higher microbial activity,abundance and diversity in sustainable agriculture. |
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