Effects Of Different Maize Straw Amendments On Soil Microbial Community Structure And Enzyme Activity

China is a big agricultural country.Each year,various types of crops produce more than 800 million tons of straw.To make full use of this resource,straw incorporation has become an important agronomic measure in various places.However,there are various ways of returning straw to the field.Different methods of returning to the field have different effects on soil physical and chemical properties,soil microbial biomass,microbial community structure and activity.Unsuitable straw incorporation method will not only cause waste of resources,but even affect soil health.How to make a reasonable return of straw to not only promote its utilization,but also to help soil quality improvement,is a problem that has not been completely solved.Soil bacteria and fungi are the two main types of soil microbes in the soil,which are selective for the utilization of nutrients and thus can respond positively to different fertilization measures.In order to reveal the response of soil microbes to different incorporation methods,and to explore the relationship between soil nutrient parameters and microbial specific communities,this study use Illumina high-throughput sequencing to observe the characteristics of soil microbial community under different straw incorporation methods.This experiment was organized on typical paddy soil(Wushan Soil)which is located in Baiji Village,Changshu City,Jiangsu Province.This study consisted of four treatments:(1)normal fertilizer(No straw addition)(CK);(2)directly incorporation of straw+normal fertilizer(CS);(3)manure with straw as raw material+normal fertilizer(CM);(4)biochar with straw as raw material+normal fertilizer(CB).The study explored the changes of soil nutrient status under different straw returning methods,and used Biolog microplate technology,real-time PCR and Illumina high-throughput sequencing to analysis the abundance,diversity and community structure of soil microorganisms.The changes of enzyme activities related to soil carbon,nitrogen,phosphorus and sulfur cycles were analyzed by fluorescence 96-well microplate assay.The main results are as follows:(1)Nutrient analysis showed that the soil organic matter increased by 3.9%,10.7%and 47.9%under the three treatments of CS,CM and CB,respectively.It shows that different maize straw amendments significantly increase the content of soil organic matter,but maize straw biochar works best,and at the same time significantly increased soil total nitrogen and available phosphorus.(2)Compared to the control the three different treatments significantly improved the ability of soil microorganisms to utilize sugars,amino sugars and amines.(3)CM and CB treatment significantly increased the soil ?-glucosidase,?-glucosidase,?-Xylosidase,Cellobiohyrolase,Acid Phosphatase and Peroxidase activities,while sulfatase and ?-N-acetylglucosaminidase activities did not significantly change.After normalizing the eight enzyme activities,it was concluded that the CM and CB treatment significantly increased the soil enzyme activity.(4)Straw incorporation increased the abundance and diversity of soil bacteria,and had a significant impact on the bacterial community structure.Soil bacteria character is significantly affected by soil pH,SOC,TN and AP.CB treatment also significantly increased the relative abundance of Nitrospirae.(5)Soil fungi were significantly affected by different straw incorporation methods.CS treatment increased soil fungal abundance but reduced soil fungal diversity;CM treatment reduced soil fungal richness but increased its diversity index;CB treatment reduced soil fungi richness and diversity.The soil fungal community structure changed under the different straw incorporation methods,and therefore straw incorporation can reduce the content of some pathogens in the soil to some extent.From the above results,it seems that different maize straw amendments have changed the effects on soil properties and nutrients and the distribution structure of soil microflora.Although all different treatments increased soil organic carbon content and the abundance and diversity of bacteria,both straw tanning and charring treatment increased soil enzyme activity.However maize straw biochar,although it reduces soil fungal richness and diversity,worked better.The latter may be related to the reduction of pathogenic fungi observed in previous field trials and the enhanced rice resistance.Based on various results,maize straw biochar is obviously more advantageous for improving and increasing the soil nutrient supply and for coordinating the soil biological growth and metabolic activity.