Study on Releasing Soil Phosphorus with Chemistry Method on Calcareous Soil

Releasing soil phosphorus with Oxalic acid, Sodium oxalic, Citric acid and Sodium citric, the results show (1) 0.1 M Oxalic acid and 0.1 M Citric acid display the certain role to release soil phosphorus mainly due to acidification, but Citric acid's effect is more evident. Sodium oxalic and Sodium citric do not show this role. (2) The role of releasing phosphorus is varying with concentration of Oxalic acid or Citric acid. Oxalic acid's role increasing with the concentration, but Citric acid's role is limited. It shows that Citric acid's role of acidification is weaker and of fixing phosphorus is stronger than Oxalic acid's one. (3) The evident role of releasing phosphorus, Oxalic acid is in 48 hours, but Citric acid is only in 6 hours. Whether Oxalic acid or Citric acid, their role is decrease with acting time.