Abstract: The residual effect and the fixation and transformation principles , the efficiency of water-soluble phosphorus fertilizer during experiment period on a calcarious soil are studied from 1982 to 1989.The economic efficiency of different distributions is also evaluated. The results show a significant residual effect for phosphorus fertilizer exists and, a longer dosage, the residual effect duration is longer. At the application rate of 16kg/P2O5/mu, its residual effect lasts at least 4 years. There is less than 20% of phosphorus which remained soluble and about 80% of phosphonus which converted into insoluble phosphates after been applying the soil. The formed afterwards insoluble phosphate in soil can be released and used by the crop again. The forms of phosphorus converted to insoluble phosphate are mainly Ca-P and Al-P which is converted to Ca-P during the 4 year period. Al-P also has a high correlation with available phosphorus. The correlative equation shows every 10ppm increase in Al-P may result in 3ppm increase in available phosphorus. Therefore, it is regarded that Ai-P has a relatively high availability and it produces mainly the residual effect.The most optimum application is 4kg P2O5/mu yearly. Instead of a big dosage at one time,suitable ones yearly are recommended.

Key words: Calcarious soil, Residual effect of phosphorus fertilizer, Forms and transfomation of phosphorus, Fertilization