Effect Of Slag And Biochar Amendment On Greenhouse Gases Emissions And Microorganisms In Paddy Fields

In order to reduce greenhouse gases emissions in paddy fields,the effect of single and mixed amendment of slag and biochar on gases emissions related microorganisms?bacterial,fungal,nitrobacteria,denitrobacteria?using gradient plate method and MPN method were detemined and the soil physicochemical properties were also determined.PCR-RFLP and high throughput sequencing were conducted to characterize the methanogens and methanotrophs community structure,respectively.And the abundance of mcrA and pmoA genes were determined via quantitative PCR.Gas measurements were performed among different amendments in paddy fields.Based on the above,some conclusions were given as follows:1.In elongation and ripen stage both early and late paddy fields,mixed amendment significantly increased soil salinity and pH,moreover,slag amendment increased pH,and biochar amendment increased soil organic carbon and carbon-nitrogen ratio.Both three kinds of amendments decreased the populations of bacterial,nitrobacteria and denitrobacteria while waste amendment had little influence on the populations of fungal.Biochar and mixed amendment increased the fungal:bacterial ratio.2.Under waste amendments,soil salinity,pH,bulk density,organic carbon and carbon-nitrogen ratio were negatively correlated with bacterial,nitrobacteria and denitrobacteria in paddy fileds.Soil bulk density,organic carbon,total nitrogen and carbon-nitrogen ratio were positively correlated with fungal:bacterial ratio in paddy fileds.3.Early paddy fields in elongation stage,slag amendment significantly increased methanogens abundance while mixed amendment increased methanotrophs abundance and increased the ratio of pmoA and mcrA.Late paddy fields in elongation stage,mixed amendment significantly increased methanogens and methanotrophs abundance and increased the ratio of pmoA and mcrA while slag amendment significantly decreased methanotrophs abundance.4.Early paddy fields in elongation stage,three kinds of amendments increased diversity of methanogens,slag and biochar amendments increased diversity of methanotrophs,and mixed amendment decreased diversity of methanotrophs.Late paddy fields in elongation stage,three kinds of amendments increased diversity of methanogens,moreover,biochar and mixed amendments increased diversity of methanotrophs,furthermore,slag amendment decreased diversity of methanotrophs.6.In elongation stage both early and late paddy fields,the dominant methanogens genera in soil were Methanoregula,Methanocella and Methanobacterium.Methylocystis,Methylosarcina and Methylogaea were dominant methanotrophs.Early paddy fields in elongation stage,biochar amendment decreased the relative abundance of Methanosarcina,and slag and mixed amendment increased the relative abundance of Methylocystis,moreover,both treatments decreased the relative abundance of Methanomassiliicoccus and Methylomonas.Late paddy fields in elongation stage,biochar amendment decreased the relative abundance of Methanosarcina,and both treatments increased the relative abundance of Methylocystis while decreased the relative abundance of Methanomassiliicoccus and Methylomonas.7.Greenhouse gases emissions were reduced after waste amendment.Comparison with three kinds of treatments,biochar and mixed amendment had better effect on reduced CO₂ and CH₄ emissions,and slag and biochar amendment had better effect on reduced N₂O emissions.