STUDIES ON THE PHOSPHORUS STATUS OF THE SOILS IN SHANGHAI
Fu Ming-hua and Chen You-song (Soil and Fertilizer Institute of the Shanghai Academy of Agricultural Science)
The present paper mainly deals with the phosphorus status of the soils in the suburbs of Shanghai. Two different methods were employed to extract the different forms of phosphorus in the soils. The results obtained showed that inorganic phosphorus comprised about 90% of the total phosphorus, and of the inerganic phosphorus calcium phosphate accounted for more than 50% . 70--80% of calcium phosphate took the forms of rock phosphate. Moreever, determination of the transformation of phosphorus in paddy soil by ~(32) P labelling method revealed that, after the application of phosphorus fertilizer to the soils, at first, the majority of phosphorus existed in the form of Al-P, then gradually converted to Fe-P, and finally, most of them were transformed into Ca-P. Through comparative study of extraction of available phosphorus in the soils and through field trials, it proved that Olsen's method is suitable for the soils in Shanghai. This article puts forward some sugestious on the application of phosphorus fertilizers to the soil in the suburbs of Shanghai.