Evaluation of phosphorous fixation capacity on river alluvium, beach ridge and coastal plain sand of Akwa ibom state, Nigeria

Abstract

Phosphorous fixation capacities of selected parent materials in Akwa Ibom State were assessed. The soils used were those derived from river alluvium, beach ridge sand and coastal plain sand. These soils were incubated with four rates of P ranging from 0, 20, 40, 80 mgl-l prepared from KH2PO4 and incubated for 1, 7, 30, 60 and 90 days. The design was 3 x 4 factorial experiment (3 soil types and 4 rates of P) fitted into Completely Randomized Design (CRD) with three replications. At a set day, the exchangeable and water-soluble (available) P were extracted with Bray P – I extractant and P not extracted by this extractant was considered fixed in the soils, using fractional recovery of P to obtained. The results showed that the available P in the soils decrease with days of incubation. Beach ridge sand had the highest fractional recovery of P while river alluvium had the least. The trend were beach ridge sand (5.04 gkg-1) > coastal plain sand (2.34 gkg-1) > river alluvium (1.07 gkg-1). The recovery of P increase with increasing P addition. The fixing capacity of the soils increased in this order: river alluvium (97%) > coastal plain sand (92%) > beach ridge sand (84%). The result also revealed that the amount of P fixed increases with increasing rates of P addition.