Effects Of Different Straw Returning Methods On Soil Microbial Diversity

China is not only a big agricultural country,but also a corn planting country,corn(Zea Mays L.)as the world’s largest crop,now planted area has exceeded rice.As a cheap agricultural waste resource,crop straw has great potential to improve soil quality and microbial environment.In the past,more research on straw return focused on evaluating its contribution to soil fertilizer efficiency and crop yield,and less research on soil microecosystems.In this study,chernozemite soil in maize planting area in Qiqihar Prefecture,Heilongjiang Province was used as the research object,and eight different methods of returning straw were set up,including flat no-till without returning to the field(RNTNS),deep turning(RB),rotational cultivation and burying(RRT),crushed and mixed land(RTM),cover return(RC),high stubble return(RLHS),strip coverage(RS),and deep pine return(RDD).High-throughput sequencing technology and real-time PCR were used to explore the effects of different straw return methods on the composition,structure and function of bacterial and fungal communities in maize rhizosphere and the basic properties of soil.This study aims to provide a theoretical basis and scientific basis for the effect of straw return on soil microbial community in maize rhizosphere and straw resource utilization.The results of this study show that:(1)After the soil was returned to the field with straw,its physical and chemical properties changed to varying degrees.Among them,the available nitrogen content of the soil after deep turning and returning to the field was significantly increased,which was 27.72% higher than that of the soil without returning to the field.The available phosphorus content of the soil after rotational ploughing and buried soil treatment was significantly increased,which increased by82.06% compared with that not returning to the field.The available potassium content was increased in the soil covered by strips,but there was no significant difference,and it was69.04% higher than that not returned to the field.The soil organic matter content of high stubble returned to the field reached the highest,which increased significantly by 61.88% compared with the non-return to the field.After strip mulching treatment,the p H reached the highest,while the deep pine covered field reached the lowest(P<0.05).(2)Soil microbial OTUs(operational taxonomic units)treated with different straw return methods can produce certain differences.Crushed soils covered to the field have the largest number of unique bacterial OTUs,and soils with high stubble returned to the field have the largest number of unique fungal OTUs.α-diversity analysis showed that soil was treated with different straw methods on the diversity and richness of soil fungal communities,and rotational cultivation and burial treatment could significantly increase the richness of fungal communities,while deep return to the field reduced the diversity and richness of fungal communities.(3)The richness and diversity of soil bacterial communities in the rhizosphere of maize were improved to varying degrees by different straw return methods.An effective method that can significantly improve the microbial diversity of rhizosphere soil is to cover the return treatment.In contrast,the relative abundance of Proteobacteria phylum and Acidobacterium phylum in soils that were only treated with deep turning and covered with deep pine return showed a downward trend.The relative abundance of ascomycetes was significantly improved by band-covering treatment.The relative abundance of ascomycetes in soil treated with deep turning decreased significantly,while the relative abundance of basidiomycetes increased significantly.(4)RDA analysis showed that soil available potassium content was the main driver of differences in bacterial and fungal community structure.Principal component analysis showed that compared with the treatment without returning to the field,the soil bacterial community flora covered with the return treatment was greatly changed,and the soil fungal community flora under the deep turning treatment was greatly changed,which accelerated the succession of microbial communities.Straw return can improve the functional abundance of carbohydrate metabolism,amino acid metabolism and biodegradation and metabolism of exogenous substances of soil bacteria.Significantly reduce the functional abundance of animal pathogenic fungi/plant parasitic fungi/unclassified saprophytic fungi,inhibit the relative abundance of ectomycorrhizae,and inhibit the flora of lichen parasitic fungi/plant pathogens/plant pathogenic fungi.