Response Of Microbial Characteristics Of Rhizosphere Soil To Mulching In Dryland Wheat

Agricultural mulching technology is one of the important cultivation measures in the semi-arid area of Northwest China.Mulching has obvious effects of water storage,moisture retention,and regulation of ground temperature.The impact of the mulch on the microclimate of the farmland will inevitably cause changes in soil microbial characteristics,which will affect the material cycle and energy flow of the ecosystem.In this study,three mulching methods of corn straw stripe mulching,plastic film mulching(PM)and no mulching(CK)were set up,the planting belt(SM)and covering belt(SD)of straw stripe mulching,PM and CK were compared and studied the microbial community structure of rhizosphere soil,microbial activity,and the effects of abiotic factors such as soil moisture and temperature between the jointing and maturing stage.The main conclusions are as follows:1.Mulching significantly improved the abundance and diversity of soil microbial flora,and had a more obvious effect on bacterial abundance.Compared with CK,the increasing in the abundance of microflora with straw banding was greater than plastic film mulching,and the increasing of the covering belt was greater than that of the planting zone.2.Among bacteria,Proteobacteria,Acidobacteria and Actinomycetes were the main core bacteria,and Ascomycota,Basidiomycetes and Mortierellomycota were the main core fungi.SD had a greater impact on the core flora,and compared with CK,it significantly increased the relative abundance of Proteobacteria,Acidobacteria,Nitrospirae,and Basidiomycota in fungi,but significantly reduced the relative abundance of Ascomycota and Mortierellomycota in fungi.3.The effect of mulching on soil enzyme activity varied greatly depending on the type of mulching and the type of enzyme;inter-annual,the difference between treatments in 2018 was larger.SD significantly reduced the activities of soil catalase,invertase,urease and alkaline phosphatase compared with CK;SM significantly increased the activities of invertase,catalase and alkaline phosphatase compared with CK,and the effect on urease had inter-year differences,SM reduced urease activity by 15.5% compared with CK in 2018,but increased by 9.6% in 2019;PM increased catalase and sucrase activities,and had an inter-annual difference with the impact on alkaline phosphatase and urease activities,compared with CK in 2018,increasing the activity of alkaline phosphatase by 6.71% and decreasing the activity of urease by 3.04%,which had little effect on the activities of the two enzymes in 2019.4.The mulching cultivation was beneficial to increase soil microbial biomass carbon(MBC)and microbial biomass nitrogen(MBN)content,with the largest increasing in SD.Overall coverage had increased MBC / MBN compared to CK,with the increase in SD and PM being larger,respectively 16.67% and 34.10% higher than CK.5.The mulch had a significant effect of temperature reduction and moisture increasing on the 0-20 cm topsoil,and the temperature reduction and moisture increasing range were the largest in SD;the mulch increased pH slightly compared with CK.The effect of mulch treatment on the nutrient status of 0-20 cm soil was quite different.SD generally increased the content of soil organic matter,nitrate nitrogen,available phosphorus,and available potassium,which were higher than CK 2.8%,17.8%,14.8%,21.0%,the content of each nutrient of SM is similar to CK,and PM generally reduced the content of each nutrient.6.Changes of soil moisture and temperature were key factors,which driving changes in microbial activities.The effect of increasing the moisture content of coverage can increase the activity of alkaline phosphatase and the content of MBC and MBN.The changes of microbial core flora were driven by the changes of soil biological factors and abiotic factors jointly.The relative abundances of Acidobacteria,Nitrospirae and Basidiomycota were significantly or very significantly correlated with soil water content positively,and significantly or extremely significantly correlated with temperature negatively.7.Changes in soil microbial activities,quantities,and species significantly affect soil nutrient status.Soil organic matter was significantly correlated with soil catalase,urease and sucrase activities negatively,and significantly correlated with relative abundance of Acidobacteria and Nitrospirae positively;Nitrate nitrogen was significantly correlated with relative abundance of Acidobacteria positively,and Actinobacteria and Ascomycota of the relative abundances were highly negatively correlated;the relative abundances of Proteobacteria and Mortierellomycota were highly correlated with the contents of available phosphorus and ammonium nitrogen.