Effect of seaweed on phosphorus available of a soil derived from volcanic ash.

Abstract

A volcanic ash-derived soil was incubated uo to 93 days with different amounts of seaweed. P was then extracted using an anion exchange resin method, and it was found that extractable P increased with increasing amounts od seaweed, which was added in proportions of .1, .5, 1.5 and 4.0%. Radishes grown in the same soil-seaweed mixtures absorbed more P than from the control and increased their yield with the increase of seaweed. On adding seaweed and KH2PO4, simultaneously to the soil, an interaction between seaweed, in a decrease in P fixation. This could be due to the presence of alginates of alginic acids in the seaweed, since these compounds could be binding exchangeable Ca of the soil and therefore diminish P fixation by the Ca-bonding mechanism.