After 90 days' cultivation of five different plants (rye grass, lupin, buckwheat, rape, amaranth), fresh samples of three
soils (yellow brown soil, paddy soil, red soil) were collected and contents of several main inorganic
phosphorus forms were measured before and after
air-drying. The results clearly indicated that total inorganic phosphorus and their composition differed signficantly among soil types. The air-drying process increased the total inorganic phosphorus in yellow brown soil and paddy soil, while decreased that in red soil. The total inorganic phosphorus could even vary to 70 % of the value before air-drying. After air-drying, the inorganic phosphorus forms in different soils changed to different extends. As for yellow brown soil, Al-P decreased, while O-P and Ca-P increased. As for paddy soil, Al-P and Ca-P rose, while Fe-P and O-P remained unchanged. As for red soil, Al-P and Fe-P increased, Ca-P remained unchange and O-P reduced obviously. Cultivation of different plant materials in soil had effects on inorganic phosphorus forms during the process of air-drying. Therefore, in chemical study of soil phosphorus, the application of fresh soil samples can provide more reliable results