Evaluation of Viability of Rocks from Selected areas of Rift Valley, Eastern and Coastal Regions in Kenya for Phosphate Fertilizers Production

Abstract

The use of fertilizer is quite essential to ensure food security in Kenya since most of Kenyan soils are poor in plant nutrients. Most of the fertilizer used in Kenya is imported. Phosphate rock is the basic material used in phosphorus fertilizer production. Rock phosphorus fractions were determined using UV/Visible Spectrophotometry after derivatization with Ammonium molybdate solution to produce a coloured complex. This study determined the percentage of phosphorus fractions in phanerozoic marine rock sediments in the coast and lacustrine and alluvial rock sediments in the Eastern, and Rift Valley of Kenya, suspected to have substantial amounts. Sampling was done from three areas in Kenya that are suspected to have the phosphate rock. The results of the study indicate that Ikutha rock phosphate percentage is sufficient to be exploited in fertilizer manufacture or for use as raw phosphate rock because Inorganic Phosphorus contributes 83.28% of total phosphorus. Lead and Cadmium, which are heavy metals, occur naturally with the phosphates in the rocks while Zinc influences the uptake of Cadmium from the soli by plants. Heavy metal concentrations were determined using atomic absorption spectrometry after digesting with tri-acid digestive mixture of sulfuric acid (H2SO4), nitric acid (HNO3) and perchloric acid (HClO4) in a ratio of 3:1:1. The results show that the heavy metal concentration in the phosphate rocks is below the threshold for fertilizer production. The concentration of Pb in all the samples was below 0.5 mg/kg while Cadmium levels in all the samples were below 0.4mg/kg.