Studies of the uptake of phosphorus by plant from soils and phosphatic fertilizers were conducted in pot culture experiments with the application of irradiated rock phosphate powder and labelled superphosphate. The soils used were a red soil, a yellow drab soil of slightly acid reaction and a calcareous light colored meadow soil. Fractionation of soil phosphorus was given in the report. Experiments revealed that, when powdered rock phosphate was applied to a calcareous light colored meadow soil at the rate of 5.64 grams per 6.0 kilograms of soil, no response in crop yield was observed, although the plants took up 35% of their absorbed phosphorus from the fertilizer. In a similar experiment with red soil deficient in phosphorus, more than 80% of the plant phosphorus was originated from rock phosphate, and soyabean and buckwheat showed marked increase in yield with the application of this fertilizer. In the experiment with yellow drab soil, millets took up almost equal amounts of phosphorus from the soil and rock phosphate, and significant response in yield of grains was found. When a mixture of 5.64 grams of powdered rock phosphate and 0.90 grams of superphosphate was applied to each of the above mentioned soils, it was found that the proportion of uptake of phosphorus by millet in a calcareous light colored meadow soil was 40 from soil;42 from superphosphate; 18 from rock phosphate. The proportion of phosphorus uptake by millet in a yellow drab soil from the respective sources was 54:12:34 and by soyabean in a red soil, 15:4:81.When powdered rock phosphate was incubated with organic manure, tracing technic showed that no increase in the availability of rock phosphate to wheat was observed after incubation.