Determination of phosphorus fractions in selected soils of southeastern Nigeria. – V. E. Osodeke and A. F. Ubah
The phosphorus fractions of soil samples from sixteen locations selected from southeastern Nigeria were determined. Available phosphorus was extracted by 2 methods (Bray – P-1 and Bray-P-2). Other forms of P were also determined. The results obtained indicated that total soil P varied from 125 to 750μgg-1 and organic P from 20 to 180μgg-1. The values of the active inorganic P forms for the various soils varied from 1.17 μgg-1 to 101.5 μgg-1 for Al-P, 3.5 μgg-1 to 189 μgg-1 for Fe-P and 1.5 μgg-1 to 4.7 μgg-1 for Ca-P. The relative abundance of the various inorganic P forms was in the order of inactive P>Fe-P>Al-P>Ca-P. Available P extracted by the two methods correlated significantly with Al-P and organic P. The higher correlation coefficient with Al-P showed that it contributes more to soil available P in these soils. In addition, the levels of phosphorus in these soils portray the need to understand the role played by the various forms of P in any phosphorus fertilization programme.
Keywords: Phosphorus fertilization, phosphorus fractions.