Abstract: The method of soil phosphorus fraction was used to study the effect of organic acids on inorganic phosphorus fraction transfer from calcareous and acidic soils. The results indicated that the effect of organic acids on soil inorganic phosphorus fraction was obvious. After treatment with citric and oxalic acid, the content of Ca2-P, Ca8-P and O-P increased, while the content of Ca10-P, Fe-P and Al-P decreased on calcareous soils. After treatment with citric and tartaric acid, the content of Al-P increased, meanwhile the content of Ca-P, Fe-P decreased and the content of O-P kept stable on acidic soils. Organic acids can improve soil phosphorus availability by affecting the inorganic phosphorus fraction and mobilizing soil sparingly soluble phosphate. The results also revealed the content of soil inorganic phosphorus could be increased by applying phosphorus fertilizer.

Key words: Low-molecular-weight organic acids, Soil, Inorganic phosphorus fraction transformation