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.