We investigated in phosphorus (P) status of 12 well-drained to moderately well-drained soil profiles along an east-west transect in the Niger Delta area of Nigeria, by determining available P estimated by the methods of Bray and Kurz no. 1, Bray and Kurtz no. 2, Olsen and Truog, and the various P fractions. Total P in the six profiles of soils developed on Coastal Plain sands (CPS) ranged from 281 to 1469 ppm mean, 821), and total P in the four profiles of soils developed on Meander Belt deposits (MBD) and Sombreiro Warri deposits (SWD) ranged from 63 to 293 ppm (mean, 133). The two profiles in the transitional zone between CPS and SWD had total P of 326 to 595 ppm (mean, 441). Organic P ranged from 11 to 338 ppm and constituted 3 to 44% of total P. Inactive inorganic P accounted for 9 to 65% of total P. The relative abundance of the various active inorganic P forms was, in decreasing or der, Fe-P, Al-P, and Ca-P, except in three of the profiles of MBD-SWD region, where Ca-P was nearly equal to or slightly higher than Al-P. The results showed high availability of P in CPS soils, medium availability of P in the transitional zone, and low P in the MBD and SWD regions. The distribution of P fractions indicated a low degree of development of the soils, especially the MBD and SWD soils.
Total P was significantly correlated positively with percentage of clay and negatively with pH and percentage of sand. Fe-P and Al-P had significant correlation with total P, percentage of sands, percent-age of clay, and available P extracted by the methods of Bray and Kurtz no. 1, Bray and Kurtz no. 2, and Truog.