Pot and field experiments on the response of rice crop to phosphatic fertilizer (labelled) were conducted on six typical acid paddy soils of Southern China. Good correlations. with mean value γ around -0.98,-0.99 have been found between the response of phosphatic fertilizer and the "A" values of Fried and Dean's method and the "x" values of Sokolov's method. Nitrogen, however, used to be the limiting factor of rice production in these areas and, in these cases, the interaction of nitrogen and phosphorus always gave good response. Under the given condition of pot experiments (0.63 gm. of P₂O₅ per 5.5 kg of airdried soil), the uptake of phosphorus from applied fertilizer by crops varied from 10 to 20%.