Study On The Effect And Mechanism Of Temperature And Microbial Diversity On Degradation Of Rice Straw In Soil

Crop straws are valuable biological resources.Straw-return is a sustainable approach for managing and recycling crop straw waste and for improving the soil physical properties,the nutrient circulation and the soil fertility.However,the bio-degradation returned straws is slow under natural conditions,especially in the areas with low temperature and poor soil condition due to lower microbial activity and diversity.Based on a 16-week laboratory experiment,this study simulated the degradation process of rice straw in three land use types（forestland soil,farmland soil and abandoned farmland soil）to explore the effects and mechanisms of temperatures（25℃and 35℃）and initial soil microbial diversity(soil dilution of 10^-1,10^-3 and 10^-6)on rice straw degradation in different soils.The this work can provide a scientific basis for the rapid decomposition of returned straw in production practice.The main findings of this work are described as following:1.Increasing the temperature and initial soil microbial diversity were beneficial to the degradation of rice straw in different soils,and promoted the production of lignocellulose-degrading enzymes such asβ-xylanase,cellobiohydrolase,manganese peroxidase and laccase in the straw degradation process.2.Higher temperature and initial soil microbial diversity resulted in significantly different species by changing theαandβdiversity of microbial communities during the degradation of rice stalks,and promoted the production of lignocellulase by some different species related to degradation to improve the degradation efficiency of rice stalks in soil.3.Increasing temperature could promote the degradation of rice stalk by the production of lignocellulase in the soil,which was driven by 3 bacterial communities in the abandoned farmland soil,5 bacterial communities in the farmland soil in the farmland soil,and 10 bacterial communities in the forestland soil.Under the condition of high temperature,the increase of initial soil microbial diversity could promote the degradation of rice stalk by the production of lignocellulase in the soil,which was driven by 1 bacterial communities in the abandoned farmland soil,2 bacterial communities in the farmland soil,and 5 bacterial communities in the forestland soil.4.Increasing temperature could promote the production of lignocellulase by fungi communities such as Acrophialophora and Humicolain farmland soil to promote straw degradation.Under the condition of high temperature,increasing the initial soil microbial diversity can only drive the production of lignocellulase in the forestland soil of Ascomycetes to promote the degradation of straw in the soil.Together,higher temperature and initial soil microbial diversity accelerated the rice straw might due to alerting the succession of bacterial and fungal communities,which drived the lignocellulase production by some key microorganisms.In addition,the effects of temperature effect and initial soil microbial diversity effect are heterogeneous in different land use types.