Pedogenic Forms of Phosphorus in Soils Underlain by Amphibolite Rocks in Selected Areas of Southwestern Nigeria

Аннотация

The study was designed to examine the pedogenic forms of Phosphorus (P) in soils underlain by amphibolite rocks in Southwestern Nigeria. Two profile pits were dug at Ajindo, Ekiti State and Wonu, Apomu, Osun State. The soil samples collected from the identified horizons were analysed for particle size distribution, soil pH, organic matter, exchangeable acidity, exchangeable cations, total P, available P and water extractable P. Correlation analyses were carried out between the P forms and some soil chemical properties. Soil pH and water-soluble P increase down the soil profiles while soil organic matter, total P, available P, Exchangeable cations, and exchangeable acidity decrease down the soil profiles. Total P in the profiles ranged between 600 and 4800 mg kg-1, available P varied between 20.80 and 33.00 mg kg-1 and water extractable P varied between 0.19 and 5.53 mg kg-; there was a positive correlation between available P and water-soluble P and organic matter content in profiles 1 and 2. Such results indicate that the present level of available P favours an increase in water-soluble P. There was a significant positive correlation between watersoluble P and pH in profile 1 and a significant negative correlation in profile 2. The study concluded that Phosphorus would not be a factor limiting crop yield in the two areas. Therefore, soil fertility management should focus on maintaining the soil's phosphorus level through organic manure and mulching