石灰性土壤磷素的化学活化途径探讨

用草酸、草酸钠、柠檬酸和柠檬酸钠作为活化剂，加人不同含磷水平土壤中，通过室内培养试验和分析，结果表明：(1)0．1M草酸和0．1M柠檬酸都有一定的活化土壤磷素的作用，草酸作用最为显著。而相同浓度的草酸钠和柠檬酸钠未显示对土壤磷素的活化效果。(2)对土壤磷素的活化作用，草酸随其浓度的增加而增强，而柠檬酸活化土壤磷的能力有限。(3)柠檬酸在加人的6h之内，对活化土壤速效磷作用明显；而草酸在加人的48h之内，对活化土壤速效磷有十分显著的作用。无论是柠檬酸还是草酸，在其对土壤速效磷发挥活化作用期间，均随加人时间的延长而减弱。

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.