The study results showed that under the conditions of pH 6.5,7.5 and 8.5, the content of rapidly available phosphorus increased
with the drop of pH value of
solutions whentreated with Ca2 - P,Ca8 - P and Ca10 - P; the content decreased with drop of pH value of solutions when treated with Fe - P and Al - P; when CaCO3 was added, the
availability of all phosphate forms significantly reduced; and the less the pH value is, the more markedly the availability reduced. Uptake rate of all phosphate form by wheat seedling increased with drop of PH value of solutions. When there existed CaCO3 , the uptake rate of phospohorus by wheat seedling significantly reduced, but with increase of pH value of solutions, the difference between the two treatments(With CaCO3 and without CaCO3 )in uptake rate of phosphorus got less and less. Under the conditions of pH 5. 5,6. 5,7. 5 and 8. 5, the effects of pH value on the availability of phosphate in calcareous Chao soil appeard greater than that in non-calcareous Chao soil.