Paucity of research information on the agronomic effectiveness of Nigerian phosphate rocks had until recently hindered their direct application by farmers. We have investigated the behaviour of some indigenous phosphate rocks (Ogun Phosphate Rock, ORP and Sokoto Phosphate Rock, SRP) under laboratory; greenhouse and field plot conditions. Their physico-chemical and mineralogical properties as well as phosphate release in strongly acidic and mildly acid soil types and different moisture regimes were determined. Their suitability for direct application as phosphorus (P) fertilizer for maize (Zea mays), millet (Pennisetum glaucum) and oil palm (Elaeis guineesis) seedlings were tested in comparison with single super phosphate. Here, their agronomic efficiency in field studies at selected agro-ecological zones and soil types is reviewed. The results of chemical and crystallographic tests revealed the carbonate fluorapatite nature, the high total P content (ORP = 30.50% P2O5; SRP = 32.5% P2O5) and their soil ameliorating (liming) potential (ORP = 19.2% CaO; SRP = 44.2% CaO). ORP and SRP are reactive phosphate rocks, since more than 30% of P content are soluble in 2% citric acid. Unlike SRP with low Fe2SO4 and Al2O3 contents, ORP by virtue of its high Al and Fe oxides (6.9 and 7.3%) might be less suitable for partial acidulation. The chelating effect of the admixture of ground rock phosphate with poultry manure facilitated the solubilization of rock P and resulted into higher agronomic effectiveness. The results showed that SRP and ORP could be conveniently used for direct application in the humid and sub-humid zones with rainfall above 1200 mm. Low rainfall of semi-arid zone would be inadequate for their solubilization.
PDF References Citation
How to cite this article
Ezekiel Akinkunmi Akinrinde and Gabriel Olufemi Obigbesan, 2006. Benefits of Phosphate Rocks in Crop Production: Experience on Benchmark Tropical Soil Areas in Nigeria. Journal of Biological Sciences, 6: 999-1004.
- Akinrinde, E.A., O.A. Onanuga, O.S. Bello and G.O. Obigbesan, 2003. Efficiency of indigenous ground phosphate rocks, organic fertilizer and their mixtures for maize performance in two Nigerian alfisols. Moor J. Agric. Res., 4: 1-7.
- Chien, S.H. and R.G. Menon, 1995. Factors affecting the agronomic effectiveness of phosphate rock for direct application. Fertil. Res., 41: 227-234.
- Jones, J.B., B. Wolf and H.A. Mills, 1991. Plant Analysis Handbook: A Practical Sampling, Preparation, Analysis, and Interpretation Guide. Micro-Macro Publishing, USA., ISBN: 9781878148001, Pages: 213.