磷添加对长期缺磷稻田土壤磷转化和甲烷排放的影响OA

This study took long-term phosphorus-deficient paddy soil as the research object.Pot experiments were conducted with a phosphorus application treatment(NKP)and a no-phosphorus application treatment(NK).The effects of phosphorus addition on phosphorus fractions,phosphorus-transforming microorganisms,methane(CH4)production and rice growth in phosphorus-deficient soil were systematically analyzed.The results showed that phosphorus addition signifi-cantly increased soil total phosphorus and available phosphorus contents(P<0.05).Soil inorganic phosphorus was domina-ted by iron-bound phosphorus(Fe-P)and calcium-bound phosphorus(Ca-P),while organic phosphorus was composed mainly of labile and moderately labile fractions.The absolute content of each phosphorus fraction increased with phosphorus addition,but its proportion to total phosphorus decreased.Phosphorus addition inhibited soil phosphatase activity and the expression of phosphorus-transforming functional genes,and the inhibition was much stronger at the tillering stage than at the maturity stage.Phosphorus addition did not alter the community structure of methanogens,but it drove a significant proliferation of Methylomonas and inhibited the proliferation of Methylobacter among methanotrophs,which may be a key factor in reducing the peak methane emission from paddy soil at the tillering stage.Correlation analysis indicated that methane emission was significantly nega-tively correlated with occluded phosphorus content and labile organic phosphorus content(P<0.05).This may be related to the"physical barrier"effect of occluded phosphorus in hindering the diffusion of methanogenic substrates,and to the nutri-tional support provided by labile organic phosphorus for methanotrophs.Furthermore,compared with the no-phosphorus treatment,phosphorus addition significantly increased rice yield and plant phosphorus uptake(P<0.05).In conclusion,phosphorus addition to long-term phosphorus-deficient paddy soil can reduce methane emission flux from the paddy soil at the tillering stage and increase rice yield by regulating soil phosphorus cycling and the methanotrophic community.