Effect of algae on phosphorus sorption characteristics of an ultisol of Southeastern Nigeria

Abstract

A pot experiment was carried out in a Green House at Michael Okpara University of Agriculture, Umudike, to investigate the phosphorus sorption characteristic of soil treated with algae. The experiment was a 2×2 factorial in completely randomized design and soil samples were collected from 0-20 cm depth of a sandy-loam soil from the University Research farm. The treatment comprised of five rates (0, 1, 2, 3 and 4 t/ha) algae and each treatment replicated three times giving a total of fifteen observational units. The data generated from the sorption studies were fitted into Freundlich model and from P-sorption isotherms, the Standard Phosphorus Requirement (SPR) of these soils were calibrated. Results showed that application of algae to the soils increased the soils available phosphorus which in-turn influenced the SPR of these soils. The SPR values ranged from 90 mg/kg in the control to 10 mg/kg in the 4 t/ha algae treated soil which showed an inverse relationship between the SPR and the rate of application of algae. Results also showed that, the P-sorption capacity, the affinity coefficient (bonding energy) and the maximum buffering capacity (MBC) were lowest in the 4 t/ha algae treated soil.  It is therefore recommended that to satisfy the phosphorus need of both soil components and plant nutrition, 4 t/ha algae should be applied in ultisols of southeastern Nigeria for sustainable crop production.