化肥有机替代对土壤磷有效性和水稻产量的影响OA

To explore the effects of straw return,either alone or in combination with animal manure,and of repla-cing part of the chemical nitrogen(N)fertilizer on paddy soil phosphorus(P)availability and rice yield,we con-ducted a field experiment with four treatments in a hilly paddy field of central Sichuan.The treatments included un-fertilized control(CK),chemical N,P,and potassium(K)fertilizer(NPK),pig manure in combination with straw return and replacing part of chemical N fertilizer(MSNPK),and straw return alone and replacing part of chemical N fertilizer(SNPK).The results showed that the SNPK treatment significantly increased labile organic P(NaHCO3-Po)and moderately labile organic P(NaOH Ⅰ-Po)contents,and decreased labile inorganic P(NaH-CO3-Pi)and highly stable organic P(NaOH Ⅰ-Po)contents compared to NPK treatment.The MSNPK treatment led to a significant increase in water-soluble P(NH4Cl-Pi)and moderately labile inorganic P(NaOH Ⅰ-Pi)con-tents,and a significant decrease in NaOH Ⅰ-Po and NaOH Ⅰ-Po contents compared to NPK and SNPK treat-ments.Moreover,the SNPK treatment significantly increased soil organic carbon(SOC)content,alkaline phospha-tase activity,rice P uptake,yield and aboveground biomass compared to NPK and MSNPK treatments.Results of correlation analysis revealed that SOC,alkaline phosphatase,and P uptake were significantly positively correlated with rice yield and aboveground biomass.In addition,NH4Cl-Pi and NaHCO3-Po showed significantly positive cor-relation with rice P uptake,yield and aboveground biomass.Results of partial least squares path modeling(PLS-PM)further indicated that NaHCO3-Po could directly affect NH4Cl-Pi or indirectly affect NH4Cl-Pi by influencing NaHCO3-Pi under the catalytic hydrolysis of alkaline phosphatase.Overall,the straw return along and replacing part of chemical N fertilizer can enhance the activity of soil alkaline phosphatase and its mediated organic P fraction mineralization process.This approach can increase the paddy soil P availability and rice P uptake,yield,and aboveground biomass,thus can be used as a suitable fertilizer application method for the hilly paddy fields of cen-tral Sichuan.