Study On The Mechanism Of Phosphorus Solubilization Of Sugar Acids

Biological phosphorus is an important part of the utilization of phosphorus in plants in nature.Sugar acids such as gluconic acid,xylonic acid,and 2-ketogluconic acid are important chemicals in biological phosphorus solubilization,but the mechanism of dissolving insoluble phosphate is not completely clear.In this paper,the formation of complexes between sugar acids and metal ions to cause phosphate dissolution were quantitatively studied.Xylonic acid and 2-ketogluconic acid samples were prepared by fermentation using Klebsiella pneumoniae as the producer.Calcium,magnesium ions and sugar acids compounds were arranged in different ratios of solutions,and the concentration of free calcium and magnesium ions in the solution was measured by an ion electrode.The results showed that the sugar acid compounds were able to form a relatively stable complex with calcium and magnesium ions,respectively,thereby significantly reducing the concentration of free calcium and magnesium ions in the solution.The stability constants of complexes of gluconic acid,xylonic acid,and 2-ketogluconic acid with calcium ions were:66.1,109.7,and 19.2 L/mol,respectively;the stability constant of complexes formed with magnesium ions were:106.3,161.2,and 23.8 L/mol,respectively.Compared with pure water,the phosphate dissolved from calcium phosphate in 4.84�10^-1 mol/L sugar acids increased from 14.4 mg/L to 204.6,238.9,and 82.0 mg/L,for sodium gluconate,sodium 2-ketogluconate,and sodium xylate respectively.Similarly,in magnesium phosphate dissolution,the phosphate concentration increased from 18.3 mg/L to 318.7,1034.4,and 207.6 mg/L by the sugar acids.During the study,the addition of sugar acid compounds to the soil showed that the phosphorus concentration in the soil was increased.By applying a sugar acid compound to the soil in which the crop?tomato?was grown,when the crop is grown to a certain height,application of an appropriate amount of the sugar acid compound could promote the growth of the crop as compared with the blank control group and the positive control group.The results of this study indicate that the complexing action is an important mechanism for the dephosphorization of sugar acid compounds,and the sugar acid compounds are expected to be effective phosphate dissolving agents for agricultural production.