我国典型富硒农田土壤磷素组分特征及其影响因素分析OA

Soil selenium bioavailability is significantly influenced by phosphorus(P)fractions,yet the regional varia-bility of P components and their key driving factors in Se-rich agricultural soils remain poorly understood.In this study,36 farmland soil samples were collected from nine representative selenium-rich regions across China,covering both upland and paddy fields.Seven P fractions were determined using the Hedley sequential extraction method,in-cluding ammonium chloride-extractable P(AP),sodium bicarbonate-extractable P(BP),sodium hydroxide-soluble P(NIP),apatite-type P(HP),intra-aggregate P(NIIP),organic P(OP),and residual P(ResP).Soil physicochemical properties were analyzed,and redundancy analysis(RDA)was applied to identify the major environmental controls.The results showed that P pool structure differed markedly among regions.Northern weakly alkaline soils(e.g.,Nan-tong,NT)were characterized by higher proportions of BP,whereas acidic southern soils were dominated by NIP and OP,indicating strong stabilization of P by Fe/Al oxides and soil organic matter.Several fractions reached peak levels in Bama upland soils in Guangxi.RDA revealed soil pH,available Fe(AFe),NH4+-N,and total nitrogen(TN)as the primary drivers,with the first two axes explaining 57.1％of total variance.Soil pH was positively correlated with AP and negatively associated with NIP and HP.This study provides a scientific basis for understanding phosphorus-sele-nium coupling processes and for region-specific nutrient management in selenium-rich farmlands.