Effects Of Amendments On Greenhouse Gas Emissions And Microorganisms In Upland Red Soil

In order to investigate the effects of amendments on greenhouse gas emissions and microorganism in upland red soil,based on the indoor simulation experiment,four treatments were established in the experiment,which included CK?control?,Ca(calcium peroxide,1.72 g·kg^-1),C(biochar,21.46 g·kg^-1),C+Ca.The dynamic changes of CH4,CO₂and N2O emissions in upland red soil within 120 days were studied,and the effects of dissolved organic carbon,microbial biomass carbon,soil enzyme activity,soil microbial biomass and community structure on the three greenhouse gases were investigated,which could provide theoretical basis and reference value for greenhouse gas emission reduction in upland red soil.The main results show that:?1?The changing trend of CH4,CO₂ and N2O were basically same in different treatments after the application of amendments to upland red soil.The CH4cumulative emissions followed a decreasing order of Ca,CK,C,C+Ca.In the earlier period?7 d?,the CO₂ flux under Ca,C and C+Ca treatments reached the maximum value,and after49 days,the processing of other treatments tended to be consistent with CK.Compared with other treatments,the cumulative emission of CO₂ in C+Ca treatments reduced significantly.The dynamic changes of N2O flux in different treatments showed the trend of double peak.The first peak appeared at seventh day,and the second peak appeared at seventy-seventh day.?2?The changing trend of microbial biomass carbon and dissolved organic carbon under CK,Ca,C and C+Ca treatment were basically same,which increased to the maximum within3 days,and microbial biomass carbon and dissolved organic carbon in C+Ca treatment within 120 days were significantly higher than those in other treatments.?3?The addition of biochar and calcium peroxide in upland red soil could increase soil sucrase,amylase and urease activity.Soil invertase and amylase activities gradually increased in each treatment within 7 days,and then which were in a relatively stable state.The urease activity in all treatments within 35 days had the same changing trend,which was inhibited in 3 days and activated 3 days later.?4?The application of biochar and calcium peroxide could increase the total microbial PLFAs and improve the microbial community structure in upland red soil.Total microbial PLFAs,gram negative bacteria,gram positive bacteria and anaerobic microorganism PLFAs increased significantly in all treatments within 3 days,and the average content of the total PLFAs followed a decreasing order of C+Ca,C,Ca,CK.The relative abundance of gram positive and negative bacteria was the highest,which were dominant strains,and the actinomycetes were the second only to them.Combined application of two amendments?C+Ca?had the highest comprehensive score,and the relative abundance of gram negative bacteria increased significantly,while the relative abundance of arbuscular mycorrhizal fungi decreased significantly,which had the greatest impact on microbial diversity.?5?After the application of amendments to upland red soil,regulation of soil moisture had a certain influence on greenhouse gas emissions and microorganisms.Compared those indexes at the moisture content of 18%,the cumulative emissions of CH4,CO₂ and N2O,total microbial PLFAs,soil invertase,amylase and urease activity,the average content of microbial biomass carbon and dissolved organic carbon in the whole training period were higher at the moisture content of 25%.?6?There was a significant negative correlation between CH4,N2O flux and total microbial PLFAs,while CO₂ flux had a significant positive correlation with total microbial PLFAs,gram negative bacteria and fungi.The application of amendments?biochar and calcium peroxide?could reduce greenhouse gas emissions in upland red soil,however,soil microbial biomass,invertase,amylase and urease activity,and the content of microbial biomass carbon and dissolved organic carbon increased,and the combined applicatuon?C+Ca?was the best.The application of amendments and the regulation of water would have better effects on soil microbial diversity and greenhouse gas emission reduction.