Effect of mixing slag and fertilizer on silicon availability and phosphorus fixation rate

The effect of mixing slag and fertilizer on silicon availability and phosphorus fixation rate were studied with incubation experiments.The results showed that soluble SiO2 and phosphorus fixation rate increased with moisture content,but didn't continue to increase after moisture content was higher than 150 g/kg.The greatest effect on soluble SiO2 was NPK three-factor proportion,followed by two-factor proportion,and the proportion with P had a greater effect on increasing soluble SiO2,while N,K had no evident effect on phosphate fixation rate.When the particle diameter was 0.10 mm,the soluble SiO2 and phosphate fixation rate were significantly higher than 0.25 and 1.00 mm particle diameter.However,there was no significant difference between 0.25 and 1.00 mm particle diameter.The soluble SiO2 and phosphate fixation rate increased along with increasing storage duration,whose maximum appeared between 10 and 20 days.Then they decreased gradually but slightly,and remained more or less constent.The phosphate fixation rate had a positive relationship with Fe2O3,CaO,MgO and had a negative relationship with SiO2 and available silicon in the slag.It was proved that the slag adsorbed phosphate mainly through iron,calcium and magnesium,and the existence of silicon could reduce the absorption of phosphorus effectively.