Abstract

Abdu N.

 Soil available phosphorus has been measured using chemical extractants and ion-sink methods comprising of resin membranes and FeO coated filter papers or strips. This study compared the conventional chemical extractants such as Bray-1, Olsen, and Mehlich- 3 etc with the ion-sink extraction methods. Investigations from researchers have shown the efficacy of the ion-sink methods especially the resin membranes which extract soil-available P in a similar manner as plant roots does. It can be employed for a variety of soil types irrespective of their properties. In contrast to chemical extractants that is designed for specific soil types. Resin membranes does not alter the chemical composition of the soil and therefore gives a close estimate of soil-available P. Economically, resin membrane strips can be used and re-used several times without loosing its extraction power. The size and dimension of the resin strips should be standardized to avoid disparity in the amount of P extracted when different sizes were used for same soils.