Rice Response to Phosphorus and Potassium in Fluvisol of Second Order Lowland in a Guinea Savanna Zone of Sub-Saharan Africa

Abstract

Aims: Poor management of P- and K-fertilizers can affect Nitrogen effect in rice grain yield and nutritional quality as the most limiting nutrient for rice production in second order lowland of Guinea savanna in West Africa. For the development of best management strategy of N, P and K fertilizers in this agro-ecosystem, the response surface curve of rice to P- and K-fertilizer rates was assessed with the recommended rate of nitrogen. Study Design: An agronomic trial including eleven (11) treatments in three replications was laid out in a complete randomized blocks design. Place and Duration of the Study: During three successive cropping cycles of rice in 2012, the study was conducted in M’be II valley of the Centre Cote d’Ivoire, a Guinea savanna zone. Methodology: Three rates of P- Ca(H2PO4)2H2O [30, 60 and 90 kgPha-1] as well as three of K-KCl [25, 50 and 75kg Kha-1] and their recommended rates (13 kgPha-1 and 25 kgKha-1) in the humid forest zone were the treatments. A total of 80 kgNha-1(urea) was applied in three splits to each of the micro-plots except in the control including no fertilizer. The rice variety named NERICA L19 was transplanted. Results: The results showed a synergism between K- fertilization and N-nutrition of rice likewise for P-fertilizer which has limited effect on K-nutrition. Conclusion: The rates of 10 kgPha-1 and 75 kgKha-1 were recommended for the production of high grain yield and nutritional quality of rice when applying 80 kgNha-1. However, further assessments of K and N were suggested for sustaining rice production in the studied agro-ecology.