Abstract

The effectiveness of some locally sourced phosphorus rocks (Sokoto Rock Phosphate (SRP), Crystallizer Super (CRY)) as P₂O₅ fertilizers for manuring oil palm applied on a long term basis (2000-2008) were evaluated along with conventional imported single superphosphate fertilizer at Okomu Oil Palm Plc., Ovia North East Local Government Area of Edo State, Nigeria.  The rocks were tested at the rates of 1.5, 2.5 and 3.5 kg/palm/year respectively (214.5, 357.5 and 500.5 kg/ha), and the single superphosphate at 1.0, 2.0 and 3.0 kg/palm/year (143, 286 and 426 kg/ha). Urea (N), murate of potash (K), and kieserite (Mg) were applied as basal application at the rates of 0.5 kg N, 2.0 kg K and 0.2 kg mg/palm/year (71.5, 286 and 28.6 kg/ha) to all treatment plots except the control (treatment without fertilizer application). Treatments were laid out as Randomized Complete Block Design, replicated three times. The phosphorus sources enhanced soil pH and soil nutrient availability and thereby enhanced palm development and yield.  Applied phosphorus fertilizers had significant (P≤0.05) effect on mean bunch number per palm, mean single bunch weight and fresh fruit bunch (FFB) production. Palms treated with these fertilizersperformed better than the control where no fertilizer was applied. Yield increases as rates of application increases and the optimum rates appeared to be 2.0 kg SSP, 2.5 kg SRP and 2.5 kg CRY beyond which there was no corresponding yield increase. Locally sourcedP₂O₅ competed favourably with the conventional inorganic single superphosphate as fertilizer for manuring oil palm. However, these fertilizers are better used in combined formwith single superphosphate due to their slow nutrients release and singly when Single superphosphate is not readily available.  This along with basal application of N, K and Mg at the rates of 0.5, 2.0 and 0.2 kg /palm/year (71.5, 286 and 28.6 kg/ha) is very necessary for optimum yield.

Key words: Fresh fruit bunch (FFB), oil palm, phosphorus treatment, rock phosphate, yield.