Phosphate desorption isotherms were constructed for four tropical and one British soil with different chemical properties. Phosphate was released with a oitric acid solution (0.0025M) adjusted to pH 5.7 and by using different soil/ solution ratios during 18 hours. This citrate level does not operate efficiently for high phosphate sorbing soils (i.e. Bowden Series), so that there is a competition between oitrate and phosphate for sorbing places and some disturbances in the shape of the desorption isotherms appeared. In moderated phosphate sorbing soils (Rengam Series) fairly reasonable desorption isotherms were obtained even at this low oitrate concentration (0.0025M). An almost linear isotherm curve was obtained when a higher concentration of citrate (0.1M) was used.