L'érosion hydrique des sols n'a pas été suffisamment étudiée dans la région de Bonoua au Sud-Est de la Côte d'Ivoire où l'activité économique dominante demeure l'agriculture. Par conséquent, des méthodes de contrôle s'avèrent nécessaires, afin d'assurer une gestion durable des sols et de sécuriser les productions agricoles. L'objectif de cette étude est de fournir des éléments pour cartographier la vulnérabilité multifactorielle à l'érosion hydrique. L'approche passe par une analyse des principaux facteurs de l'érosion : l'érosivité des pluies, l'érodabilité des sols, la pente et l'occupation des sols. Les cartes obtenues sont intégrées dans un Système d'Information Géographique (SIG) à l'aide d'une combinaison additive pour établir une carte de vulnérabilité à l'érosion hydrique. Cette carte est validée par des observations de terrain. Trois classes de vulnérabilité multifactorielle à l'érosion hydrique ont été distinguées : les zones à faible vulnérabilité (29 %) ; les zones à vulnérabilité moyenne (34 %) et les zones fortement vulnérables (37 %). Ainsi, dans la région de Bonoua, les classes à moyenne et forte vulnérabilité multifactorielle représentent 71 % de la superficie. Cette première ébauche cartographique est un outil devant aider les décideurs pour l'attribution des zones de cultures et des sites pouvant abriter des infrastructures socio-économiques.
Water soils erosion has not been studied enough in the region of Bonoua south-eastern Côte d'Ivoire where major economic activity remains the agriculture. Consequently, control methods are necessary in order to ensure sustainable management of soils and to secure agricultural productions. The objective of this study is to supply tools for mapping multifactorial vulnerability to water soil erosion. The method involves an analysis of the main factors of erosion: rainfall erosivity, soil erodibility, slope and land use. Obtained maps are integrated in Geographic Information System (GIS) throughout an additive combinaison to establish a vulnerability water soils erosion map. This map is validated after ground observations. Three classes of multifactorial vulnerability to water erosion have been distinguished: areas with low vulnerability (29 per cent); areas with middle vulnerability (34 per cent) and areas with high vulnerability (37 per cent). Thus, in the region of Bonoua, classes with a middle or high multifactorial vulnerability represent 71 per cent of the study area. This first map is a tool that would help decision makers in attribution of areas for agricultural activities and for socio-economic substructures

No 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 European Scientific Journal December 2017 edition Vol.13, No.36 ISSN: 1857 -7881 (Print) e -ISSN 1857 433 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.

Photo 4 e de couverture © IRD/T. Chevallier -Culture de haricots amendée par du fumier de ferme à Madagascar.