In order to assess the efficiency of different P-carriers it is necessary to know not only how it affects the total supply of available phosphate but also the rate at which the phosphate is released in an available form for the use of the plants. On the basis of the above two factors the results of these studies may now be summarised as under:- From the point of view of the total supply of available phosphorus, superphosphate as well as bone meal are almost four times as efficient as rock phosphate in the Karjat soil. Whereas the rate of supply of phosphates goes on decreasing in the case of superphosphate, that in the case of bone meal shows a continuous increase. As regards the effect of different soil amendments when used in conjunction with the phosphatic fertilisers, the total available phosphorus as well as its rate of supply is adversely affected when sulphur is applied along with superphosphate. The organic soil amendments have not produced any effect on the total as well as on the rate of supply of available phosphorus when they are added along with superphosphate. Whereas the addition of sulphur along with either rock phosphate or bone meal has increased the availability of phosphorus, the organic amendments do not seem to have any effect, mohua flowers on the other hand having depressed the rate of release of phosphorus when applied with bone meal.