Performance de l’association mixte sorgho-niébé sur les productivités du sorgho et des sols en zone Soudano-Sahélienne du Burkina Faso

Dans la zone soudano-sahélienne du Burkina Faso, la performance des associations mixtes sorgho-niébé reste faible bien que les nombreux services écosystémiques rendus par les associations céréales-légumineuses soient connus. L’objectif de la présente étude a été de comprendre la performance des associations mixtes sorgho-niébé sur la productivité du sorgho et du sol. L’étude a consisté à conduire des tests multi-locaux avec de petits agriculteurs familiaux de la région Nord du Burkina Faso. Des traitements à base de zaï simple (ZS), zaï + 9 t ha-1 de substrats organiques (ZF) et zaï + 9 t ha-1 de substrats organiques + 50 kg ha-1 d’urée (ZFN) ont été testés en 2013, chaque traitement étant répété 9 fois. En 2014, le traitement ZFN a été remplacé par le traitement zaï + 9 t ha-1 de substrat organique + 600 kg ha-1 de Burkina Phosphate (ZFP). Chaque parcelle élémentaire a abrité l’association mixte sorgho-niébé et la monoculture du sorgho. Les résultats ont montré que l’association mixte sorgho-niébé a généralement entrainé une dépréciation des rendements du sorgho par rapport à la monoculture du sorgho. Par contre, une performance significative de +58% en 2014 et un accroissement de +10% en 2013 des rendements totaux grains de sorgho et de niébé ont été enregistrés par rapport à la monoculture du sorgho. Une grande efficacité d’acquisition des nutriments par le sorgho associé au niébé a été enregistrée en comparaison à la monoculture du sorgho. Pour une meilleure performance des cultures mixtes sorgho-niébé, les traitements ZS et ZF sont à recommander pour augmenter les rendements totaux grains de niébé et de sorgho ainsi que l’acquisition de N dans les grains du sorgho ; les traitements ZFN et ZFP sont, quant à eux, sont à recommander pour améliorer la fertilité résiduelle en N et P des sols dans la région Nord du Burkina Faso. English title: Performance of sorghum-cowpea mixed cropping system on sorghum and soils productivities in the Sudano-Sahelian zone of Burkina Faso In Sudano-Sahelian zone of Burkina Faso, the performance of sorghum and cowpea mixed cropping system remains low although the many ecosystems provided associated by cereal and legume mixed or intercropping system are known. The objective of this study was to understand the performance of these sorghum and cowpea mixed cropping system on the productivities of sorghum and soils. The study consisted to multi-local tests with small family farmers in the northern region of Burkina Faso. Treatments based on simple zaï (ZS), zaï + 9 t ha-1 of organic substrates (ZF) and zaï + 9 t ha-1 of organic substrates + 50 kg ha-1 of urea (ZFN) were tested in 2013, each treatment being replicated at 9 times. In 2014, the ZFN treatment was replaced by the zaï + 9 t ha-1 of organic substrate + 600 kg ha-1 of Burkina Phosphate (ZFP). Each elementary plot was occupied by sorghum and cowpea mixed cropping system and monocropping sorghum. The results showed that the yields of sorghum mixed by cowpea generally lowered than the yields of monocropping sorghum. In contrast, a significant performance of +58% in 2014 and an increase of +10% in 2013 on total sorghum and cowpea grains yields were recorded compared to monocropping sorghum. The high efficiency of nutrient acquisition by sorghum in mixed cropping system with cowpea was recorded compared to monocropping sorghum. For better performance of sorghum and cowpea mixed cropping system, ZS and ZF treatments are recommended to increase total sorghum and cowpea grains yields, the N acquisition in sorghum grains, and ZFN and ZFP treatments were suggested to improve residual N and P fertility of soils in the northern region Burkina Faso

Caractérisation et évaluation de l’aptitude culturale d’un sol pour la production de tomate sous climat tropical semi-aride

Les connaissances empiriques de la nature des sols est une contrainte pour la mise en valeur optimale de la ressource sol au sein des petites exploitations familiales du Burkina Faso. Ainsi, pour une meilleure valorisation du potentiel des sols, la présente étude a consisté à la caractérisation et à l’évaluation de l’aptitude culturale d’un sol d’une exploitation agricole pour la production de la tomate. Le sol a été ainsi caractérisé selon les directives de la FAO (1994) et son aptitude culturale déterminée selon le manuel d’évaluation des terres du Bureau National des Sols (BUNASOLS, 1990). Les résultats des travaux révèlent que c’est un sol ferrugineux tropical lessivé induré profond et correspondrait à un Lixisol endoplinthique. Sur le plan physique, la structure est polyédrique subangulaire faiblement développée en éléments grossiers, fins et moyens dans le premier horizon et massive dans l’horizon sous-jacent. La texture du sol est limoneuse en surface, limono-argileuse dans la partie médiane et argileuse en profondeur. Sur le plan chimique, ce sol est caractérisé par un rapport C/N faible d’une valeur de 7 ; le pH était moyennement acide de 6 à 5,7 ; la capacité d’échange cationique variait de de 8,62 à 8,15 méq/100 g. Ce sol présente des carences physiques et est considéré comme déficient en éléments nutritifs. Il découle de l’évaluation qu’il a une aptitude moyenne (S2nr) pour la culture de tomate du fait de sa mauvaise condition d’enracinement et de la faible valeur de la Capacité d’Echange Cationique et des bases échangeables.   Empirical knowledge of the nature of soils is a constraint to the optimal development of soil resources on small family farms in Burkina Faso. Therefore, in order to make better use of soil potential, the present study consisted in characterizing and assessing the cultural suitability of a farm soil for tomato production. The soil was characterized in accordance with FAO guidelines (1994), and its suitability for cultivation determined in accordance with the Bureau National des Sols land evaluation manual (BUNASOLS, 1990). The results of the work reveal that it is a deep indurated leached tropical ferruginous soil and corresponds to an endoplinthic Lixisol. Physically, the structure is polyhedral, subangular and weakly developed in coarse, fine and medium elements in the first horizon, and massive in the underlying horizon. Soil texture is silty on the surface, silty-clayey in the middle section and clayey at depth. Chemically, the soil had a low C/N ratio of 7; pH was moderately acidic, ranging from 6 to 5.7; cation exchange capacity varied from 8.62 to 8.15 meq/100 g. This soil is physically deficient and considered nutrient deficient. The evaluation concluded that it has an average suitability (S2nr) for tomato cultivation due to its poor rooting condition and low Cation Exchange Capacity and exchangeable base values

Typologie et logique socio-économique des systèmes de culture associant céréales et légumineuses dans les agro-écosystèmes soudano-sahéliens du Burkina Faso

Dans la zone soudano-sahélienne du Burkina Faso, les associations mixtes céréales-légumineuses dominent les surfaces cultivées annuellement. Cependant, les rendements sont faibles et ne couvrent souvent pas les besoins alimentaires des exploitations qui les pratiquent. Afin d’améliorer la productivité de ces associations, il est nécessaire de comprendre la logique socio-économique de leurs mises en oeuvre. Dans cette optique, 60 exploitations agricoles familiales (EA) ont été enquêtées dans la région Nord du Burkina. Des analyses en correspondances multiples (ACM) font ressortir 4 types de systèmes de culture caractérisés d’une part par le niveau d’apport de matière organique et la fréquence de désherbage et d’autre part, par la présence de structures pérennes de conservation des eaux et des sols. La fertilisation organique et le désherbage fréquent sont associés aux EA les mieux pourvues en main d’oeuvre familiale, en petits ruminants et surfaces agricoles. L’âge de l’exploitant agricole et le nombre d’épouses sont de bons indicateurs des moyens économiques de l’EA. La plupart des recettes monétaires annuelles par EA varient dans la gamme très large de 25 à 300 KFCFA. Ces aspects doivent être pris en compte en vue de raisonner des propositions techniques adaptées à la diversité des EA de cette région.© 2016 International Formulae Group. All rights reserved.Mots clés: ACM, associations mixtes céréales-légumineuses, typologie des systèmes de culture, logique socioéconomique, Burkina FasoEnglish Title: Typology and socio-economic logic of cropping systems in Sub-Saharan agro-ecosystems of Burkina FasoEnglish AbstractIn Sub-Saharan zone of Burkina Faso, legumes and cereals mixed cultivation systems occupy most of the cultivated area. However, yields are low and often do not cover the food needs of farms that practise them. In order to improve the productivity of these intercropping systems, it is necessary to understand the socio-economic logic of their implementation. To this purpose, sixty family farms were surveyed in the northern region of Burkina Faso. Multiple correspondences analysis (MCA) showed four types of cropping systems characterized on one hand by the level of organic matter intake and weeding frequency and on the other hand, by the presence of permanent structures for water and soil conservation. Organic matter fertilization and frequent weeding are associated with farms with high family labor, livestock (especially small ruminants) and high cultivated area, while 70% of farmers have an off-farm activity. The age of household head and the number of their wives are good indicators of farmers’ income. Most of farmers’ monetary recipes vary widely from 25 to 300 KFCFA. These aspects must be taken into consideration for reasoning suitable technical recommendations for the farmer’s in this region.© 2016 International Formulae Group. All rights reserved.Keywords: MCA, legumes and cereals mixed cultivation systems, typology of cropping systems, socioeconomic logic, Burkina Fas

The influence of C3 and C4 vegetation on soil organic matter dynamics in contrasting semi-natural tropical ecosystems

Variations in the carbon isotopic composition of soil organic matter (SOM) in bulk and fractionated samples were used to assess the influence of C3 and C4 vegetation on SOM dynamics in semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. Differential patterns in SOM dynamics in C3/C4 mixed ecosystems occurred at various spatial scales. Relative changes in C / N ratios between two contrasting SOM fractions were used to evaluate potential site-scale differences in SOM dynamics between C3- and C4-dominated locations. These differences were strongly controlled by soil texture across the precipitation gradient, with a function driven by bulk δ13C and sand content explaining 0.63 of the observed variability. The variation of δ13C with soil depth indicated a greater accumulation of C3-derived carbon with increasing precipitation, with this trend also being strongly dependant on soil characteristics. The influence of vegetation thickening on SOM dynamics was also assessed in two adjacent, but structurally contrasting, transitional ecosystems occurring on comparable soils to minimise the confounding effects posed by climatic and edaphic factors. Radiocarbon analyses of sand-size aggregates yielded relatively short mean residence times (τ) even in deep soil layers, while the most stable SOM fraction associated with silt and clay exhibited shorter τ in the savanna woodland than in the neighbouring forest stand. These results, together with the vertical variation observed in δ13C values, strongly suggest that both ecosystems are undergoing a rapid transition towards denser closed canopy formations. However, vegetation thickening varied in intensity at each site and exerted contrasting effects on SOM dynamics. This study shows that the interdependence between biotic and abiotic factors ultimately determine whether SOM dynamics of C3- and C4-derived vegetation are at variance in ecosystems where both vegetation types coexist. The results highlight the far-reaching implications that vegetation thickening may have for the stability of deep SOM. Â © Author(s) 2015

Variability of effects of compost on nodulation, N acquisition and yield of cowpea in sub-Saharan areas of Burkina Faso

Legumes/cereals intercropping systems occupy the largest part of the surface area and are the primary food source of people in semiarid tropical regions. Because of drought and low soil fertility, the average grain yields rarely surpass 0.2 t ha-1 for the cowpea and 0.3 t ha-1 for the millet or sorghum. In the northern region of Burkina, farmers have developed the practice of sowing in bowls of about 15 cm depth and 20 cm diameter, referred to as zaï practice. The zaï bowls are made manually with a hoe. This long and tedious work aims to increase the storage of rainfall-water around the seedlings, and concentrate organic compost application. However, very little data is available on the effects of this organic amendment on the biological N2 fixation, N acquisition and grain yield of the legume. This study aimed at quantifying over three year cycles (2012-2014), the effects of an application of around 9 t ha-1 of compost (0.3 kg-1 zaï bowl) on nodules number per plant and grain yields of cowpea intercropped with sorghum in 12 farmers’ fields. The selected fields represented the various soil types found in this area, and the years of study presented contrasted rainfall patterns. The results showed that the compost application effect on the nodules number per plant varied from highly negative to highly positive depending on the field and the year. The impacts of compost application on the nutrients uptake and yield of the legume were generally positive but also very variable between situations. We will present our analysis of the causes of such variability of the compost effect and will draw the practical consequences for improving these cropping systems in a context of climate change

Adherence to HIV Antiretroviral Therapy Among Pregnant and Breastfeeding Women, Non-Pregnant Women, and Men in Burkina Faso: Nationwide Analysis 2019-2020.

Since the scale-up of antiretroviral therapy (ART) services in Burkina-Faso, achieving an AIDS-free generation depends on optimal ART adherence. However, no data exists on the population group differences on the level of ART adherence in Burkina-Faso. This study analyzes ART adherence among pregnant-and breastfeeding-women, non-pregnant women, and men in Burkina-Faso.info:eu-repo/semantics/publishe

Uptake of prevention of mother-to-child transmission cascade services in Burkina Faso between 2013 and 2020: are we on the right track?

The use of services to prevent mother-to-child transmission (PMTCT) of the human immunodeficiency virus (HIV) remains a serious challenge in sub-Saharan Africa. In the last decade, Burkina Faso has implemented numerous policies to increase the use of PMTCT services by pregnant women and their partners, as well as children. This study assesses trends in the uptake of PMTCT services in Burkina Faso from 2013 to 2020 in order to study the progress and gaps in achieving the national and international targets set for 2020.info:eu-repo/semantics/publishe

On the delineation of tropical vegetation types with an emphasis on forest/savanna transitions

Background: There is no generally agreed classification scheme for the many different vegetation formation types occurring in the tropics. This hinders cross-continental comparisons and causes confusion as words such as 'forest' and 'savanna' have different meanings to different people. Tropical vegetation formations are therefore usually imprecisely and/or ambiguously defined in modelling, remote sensing and ecological studies.Aims: To integrate observed variations in tropical vegetation structure and floristic composition into a single classification scheme.Methods: Using structural and floristic measurements made on three continents, discrete tropical vegetation groupings were defined on the basis of overstorey and understorey structure and species compositions by using clustering techniques.Results: Twelve structural groupings were identified based on height and canopy cover of the dominant upper stratum and the extent of lower-strata woody shrub cover and grass cover. Structural classifications did not, however, always agree with those based on floristic composition, especially for plots located in the forest-savanna transition zone. This duality is incorporated into a new tropical vegetation classification scheme.Conclusions: Both floristics and stand structure are important criteria for the meaningful delineation of tropical vegetation formations, especially in the forest/savanna transition zone. A new tropical vegetation classification scheme incorporating this information has been developed. © 2013 Copyright 2013 Botanical Society of Scotland and Taylor & Francis