Aluminum and iron contents in phosphate treated swamp rice farm of Mbiabet, Akwa Ibom State, Nigeria

Abstract

In 2006 aluminum and iron contents were determined in phosphate treated swamp rice farm of Mbiabet, Akwa Ibom State. The objectives were to determine the aluminum and iron contents, the effect of drying, phosphate and lime application in an acid sulphate soil grown to rice in Nigeria. The soil samples used were mud-clay from the bottom of the water-gate and cat-clay from the stream banks that bring water to the swamp. The third was from the unfertilized pond-mud taken from the Latin square of 36 x 5m, which had received surface limestone dressing of 50
kg/ha but with no phosphate. The phosphate fertilizer was applied at 122kg/ha-1 P205. Various extractants used to extract Fe and Al showed highest concentration of Fe and Al in the sulphuric acid and dithionite and lowest in the sodium hydroxide citrate extractants. The total amount of Fe and Al removed by the fractionating solution represented 75 and 15 percent respectively. The average values of pH and KCl-extractable aluminum and iron at various depths showed that as the pH decreased the amount of extractable Fe and Al increased in both fresh and dried muds down the profile. Iron phosphate was more abundant than aluminum or calcium phosphate throughout the profile and there was no aluminum phosphate present below a depth of 8 cm. These results were consistent throughout the study period.