Efficiences Des Nutriments P Et K En Riziculture Irriguée Dans Un Bas-Fond Secondaire En Zone De Savane Guinéenne De La Côte d’Ivoire

Abstract

N-nitrogen is the most limiting element in rice-growing on lowland soils in the central part of Côte d'Ivoire. In addition to its direct effect, poor management of P and K fertilizers in basic manure can induce low yields and losses of currencies. However, inappropriate use of these nutrients (P and K) in these shallows can induce other adverse effects on crops and even on the environment. So, for the eficient management of lowland ricegrowing fertiliszation, three agronomic trials have been set up in the Central part of Côte d'Ivoire to determine the optimum P and K doses to improve fertilizer efficiency in the relevant agroecology. Three rates of PCa(H2PO4)2H2O [30, 60 and 90 kgPha-1 ] as well as three of K-KCl [25, 50 and 75kgKha-1 ] and their recommended rates (13kgPha-1 and 25kgKha-1 ) in the humid forest zone were the treatments. A total of 80kgNha-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.An agronomic trial including eleven (11) treatments in three replications was laid out in a complete randomized blocks design The highest K recovery rate is obtained with the 25kgKha -1 rates, while the lowest rate is with 50kgKha-1 in the three trials. There is a gradual decrease in P-level recovery as rates increase, regardless of the test. Increased rates of P and K induce a decrease in agronomic efficiency. The partial productivity factor (PFP) of nutrients P and K decreases with increasing rates for all three trials. The highest grains and straw yields are obtained for 75kgKha-1 doses regardless of the dose of P. However, it should be noted that the different efficiencies obtained are better for the lower rates of P and K