Diagnostic de l’Etat de Fertilité des Sols Sous Culture Cotonnière Dans les Principaux Bassins de Production de Côte d’Ivoire

The study was conducted to assess the fertility potential of cotton soilsin Côte d’Ivoire. A total of 500 plots of cotton farmers in 5 regions of thecotton basin was selected for soil sampling in the horizon 0-20 cm. Thechemical analyzes of soil samples in the laboratory were performed on thefollowing parameters: particle size, pHwater, organic matter, total N, availableP, K, Ca, Mg and Cation Exchange Capacity (CEC) of soil. The physicalcharacterization revealed that the studied soils are mainly sandy texture in thesurface horizon. This gives them a very low retention capacity. The chemicalcharacterization of soils showed that they have reactions ranging from slightlyacid to neutral (6.4 <pH<7). These soils have very low levels of total organicmatter, total nitrogen, available phosphorus (in northern, south-central andwestern regions), calcium, potassium, and low values of cation exchangecapacity

Variabilité des descripteurs pluviométriques intrasaisonniers à impact agricole dans le bassin cotonnier de Côte d’Ivoire : cas des zones de Boundiali, Korhogo et Ouangolodougou

Objectif: Cette étude vise à caractériser l’évolution des descripteurs pluviométriques intrasaisonniers à impact agricole durant la saison culturale dans le bassin cotonnier ivoirien. A cet effet,Méthodologie et résultats: dix descripteurs pluviométriques intrasaisonniers susceptibles d’influencer l’agriculture ont été analysés à partir des données pluviométriques couvrant les périodes 1951-2000 et 2011-2016 et provenant des bases de données de la Société de Développement et d’Exploitation Aéroportuaire, Aéronautique et Météorologique et du Centre National de Recherche Agronomique. Les tests de tendance (Mann-Kendall) et de stationnarité (Pettitt) et une comparaison des périodes ont été appliqués aux variables déterminées. L’analyse des cumuls pluviométriques saisonniers, du nombre de jours de pluie et des précipitations moyennes journalières a mis en évidence une tendance significative à la baisse de ces paramètres sur la période 1951-2000. Les fins et les longueurs de la saison des pluies ont présenté respectivement une tendance significative à la précocité et au raccourcissement. Les autres descripteurs intrasaisonniers ont peu varié. En revanche, des ruptures statistiquement significatives ont été observées entre 1968 et 1979. La comparaison des périodes indique une dégradation des conditions climatiques pendant la période sèche (1971-2000). Ces dégradations se sont accentuées dans la période actuelle (2011-2016).Conclusion et application: Les nouvelles conditions climatiques observées dans le bassin cotonnier traduites par une variabilité des descripteurs intrasaisonniers rendent de plus en plus difficile la planification agricole. Dès lors, l’actualisation des calendriers culturaux dans le bassin cotonnier devient nécessaire.Mots-clés: Descripteurs intrasaisonniers, pluviométrie, agriculture, bassin cotonnier, Côte d’IvoireEnglish AbstractObjective: This study aims to characterize the evolution of agricultural impact intra-seasonal descriptors during the growing season in cotton production area of Côte d’Ivoire. For this purpose...Methodology and results: ten intraseasonal descriptors likely to influence agriculture were determined from rainfall data covering the periods 1951-2000 and 2011-2016 from the Airport, Aeronautical and Meteorological Development and Operations Company and the National Agronomic Research Center. Trend (Mann-Kendall) and stationarity (Pettitt) tests and an inter-period comparison were applied to the identified variables. Analysis of seasonal rainfall accumulations, number of rainy days and average daily rainfall amounts showed a significant downward trend over the period 1951-2000. The cessation and length of the rainy season showed a significant trend towards early onset and shortening respectively. Other intraseasonal descriptors do not varied significantly. In contrast, statistically significant breaks were observed between 1968 and 1979. The period comparison indicated a deterioration in conditions during the dry period (1971-2000). The comparison of the periods indicates a deterioration of the climatic conditions during the dry period (1971-2000). These degradations have increased in the current period (2011-2016).Conclusion and application: New climatic conditions observed in the cotton production area translated by a variability of intraseasonal descriptors are making agricultural planning increasingly difficult. It is therefore necessary to update the crop calendars in the cotton production area.Keywords: Intraseasonal descriptors, rainfall, agriculture, cotton production area, Côte d'Ivoir

Caractérisation Des Paramètres Agroclimatiques Clés De La Saison Culturale En Zone De Contact ForêtSavane De Côte-d’Ivoire

In the Central region of Côte d’Ivoire, contact area between the South forest estate and savanna’s area in the North, the climate is a major concern for people. Since the late 1960s, the constant changes in rainfall amounts make it difficult for the various agricultural operations in the area. Before the natural instability of the rainfall regime and the extreme variability of agro-climatic parameters, farmers are no longer able to detect the probable dates of start and end of the rainy seasons that are essential to optimize agricultural production. From the descriptive statistical analysis of rainfall data from the stations of Bouaké, Béoumi, Katiola and Dabakala over the period 1961-2000, this study focuses on assessing the dynamics of agro-climatic key factors of the growing season in this transition zone. The results show an earlier start and a later end of the rainy season in Bouaké and Béoumi. On the contrary, the seasons started later and ended earlier in the localities of Katiola and Dabakala, and the dry sequences, during the rainy seasons, are longer in these localities

Microbial Communities Involved in Fe Reduction and Mobility During Soil Organic Matter (SOM) Mineralization in Two Contrasted Paddy Soils

International audienceLowland rice fields of West Africa (Ivory Coast) and South Asia (Thailand) are affected by ferrous toxicity or salinity, respectively, and their soil waters contain large amounts of ferrous iron, depending on reducing irrigation condition and suggesting occurrence of bacterial reducing processes. To determine the involvement, dynamic and activities of bacterial communities in Fe(III) reduction and mobilization during anaerobic degradation and mineralization of soil organic matter (SOM), different experiments and analyses have been performed. Results demonstrated that the utilization of SOM as sole carbon, nutrient and energy sources favored the presence of large bacterial communities: facultative anaerobic and anaerobic bacteria, Fe(III)-reducing bacteria (FeRB) (fermentative and Fe respiring), sulfate reducing bacteria (SRB) which are involved in carbon, nitrogen, iron and sulfur cycling. The larger functional diversity is observed in the Ivory Coast paddy soils containing larger amounts of organic matter and sulfur compounds. These communities contained complementary populations (chemoorganotrophic, chemolitotrophic, aerobic, facultative anaerobic and anaerobic) that can be active at different steps of iron solubilization with simultaneous organic matter mineralization. Our results indicate that the pH controlled by bacterial activity, the nature much more than the content of organic matter, and consequently the structure and activity of bacterial communities influence significantly the availability and dynamic of iron in paddy fields which affect the soil quality