Abstract:Low availability of phosphorus (P) universally occurs in coastal saline soil. A root-bag pot experiment was conducted, 5 treatments were designed: 1) CK0, no application of P; 2) CK, conventional P fertilizer; 3) FC, application of biochar; 4) FH, application of humic acid; 5) FM, application of organic and inorganic P. The effects of different treatments on the content of available P, P fractions and P absorption were investigated for non, light and moderate saline soils, respectively. The results showed that:1) Available P contents in rhizosphere and non-rhizosphere soils decreased with the increase of soil salinity. The addition of biochar significantly increased available P in light and moderate saline soils, which were 40.72% and 84.80% higher than those of CK, respectively. 2) The salinization obstruction decreased barley yield and P absorption by barley aboveground. All treatments promoted P uptake by barley in saline soil and improved the utilization rate of P fertilizer. The yield-increasing effect was not significant in light saline soil for all treatments, while FC treatment significantly increased barley yield by 63.20% in moderate saline soil than CK. 3) Salinization obstruction reduced the proportion of soil active inorganic P, NaOH-Pi, NaHCO3-Po and NaOH-Po, but increased the proportion of HCl-Pi. In conclusion, FC treatment significantly increased the proportion of active inorganic P in saline soil, which improved the availability of soil phosphorus, and FC and FM treatments reduced HCl-Pi ratio more in moderate saline soil than in light saline soil.