Effects of long-term fertilization on the form of inorganic phosphorus and the characteristic of adsorption and desorption in black soil

Changes of inorganic phosphorus forms and the characteristics of phosphorus adsorption and desorption were studied under a long-term fertilization experiment in black soil. Results showed that the forms of inorganic phosphorus ranged as O-P < Ca-2-P < Ca-8-P < Al-P < Ca-10-P < Fe-P. Therefore, Fe-P was the main inorganic phosphorus form in this study. The capacity of phosphorus adsorption with phosphate treatments was higher than with no-phosphorus treatments. The optimal fitted equation was the Langmuir equation. Phosphorus desorption was related to the binding energy. Positive correlation between phosphorus adsorption and desorption without phosphorus addition was found; however, negative correlations among the phosphate treatments had been observed.