Kolo Matthew Tikpangi^1,, Salihu Simon Olonkwoh²

Major and trace elements composition of phosphate rocks from phosphate bearing areas of Sokoto basin north-western Nigeria were investigated using PANanalytical Minipal4 PW4025/45B energy dispersive x-ray fluorescence spectrometer (EDXRF). The results indicated that CaO, P₂O₅ and SiO₂ with mean concentration values ranging from 45.1±1.5 to 51.3±1.9 %, 19.9±1.0 to 21.6±2.2 % and 5.0±0.7 to 7.6±1.7 % respectively, are the most abundant species in Sokoto phosphate rocks (SPRs). Average concentrations of alkali metals were found to be less than 1wt % showing that very little salt will be added to agricultural soils via direct application of SPRs. The low concentration values recorded for alkali metals confirms the effectiveness of SPRs as good source of soil phosphorus. The estimated mean reactivity values varies from 2.2 to 2.4. These values underscore the suitability of SPRs as good raw material for fertilizer production. Cr, V, Cu and other studied trace elements were found to be enriched in the studied samples. Hence, direct application of SPRs can compete favourably with the conventional chemical fertilizers in enhancing the availability of soil nutrients for plant growth.

phosphate rock, major oxides, x-ray fluorescence, CaO/P₂O₅ ratio, Sokoto