Évaluation de la qualité de composts à base de biomasses feuillées de deux espèces agroforestières à Cassou, Centre-Ouest, Burkina Faso

Albizia lebbeck (L.) Benth. and Gliricidia sepium (Jacq.) Kunth ex Walp. are species of the leguminosae group which are promoted in agroforestry. This study aimed at assessing the quality of leafy biomass composts of these two species in order to use them as green manure. For this, composts based on leafy biomasses of Albizia lebbeck and Gliricidia sepium have been characterized. The phytotoxicity tests of the composts was carried out using a germination test of Zea mays (L) and Arachis hypogaea (L). The effect of composts on the growth of Adansonia digitata L. and Sclerocarya birrea (A.Rich.) Hochst. subsp. Also evaluated. Comparison of means tests and repeated measures ANOVA were used to compare types of composts. The results show that these composts were not toxic. The average carbon, nitrogen, pHe and C / N ratios of the composts of Albizia lebbeck and Gliricidia sepium were in accordance with international standards. The effect of Gliricidia sepium compost on the growth of Adansonia digitata and Sclerocarya birrea was better than that of Albizia lebbeck and cow dung (P <0.05). The compost from the leafy biomass of Gliricidia sepium is of very good quality while that of Albizia lebbeck is of fairly good quality. The biomasses of these two species therefore constitute good material for composting. These results can be used to improve crop production in agroforestry. Albizia lebbeck (L.) Benth. et Gliricidia sepium (Jacq.) Kunth ex Walp. sont des espèces de légumineuses promues dans l’agroforesterie. Cette étude visait à évaluer la qualité des composts de biomasses feuillées de ces deux espèces afin de les utiliser comme engrais verts. Pour cela des composts à base de biomasses feuillées de Albizia lebbeck, de Gliricidia sepium ont été caractérisés. La phyto-toxicité des composts a été évaluée à l’aide d’un test de germination de Zea mays (L) et Arachis hypogaea (L). L’effet des composts sur la croissance de Adansonia digitata L. et Sclerocarya birrea (A.Rich.) Hochst.subsp. a également été évalué. Des tests de comparaisons de moyennes et une ANOVA à mesures répétées ont permis de comparer les types de composts. Les résultats montrent que les composts évalués n’étaient pas toxiques. Les teneurs moyennes en carbone, en azote, les pHe et les rapports C/N des composts de Albizia lebbeck et de Gliricidia sepium étaient conformes aux normes internationales. L’effet du compost de biomasse de Gliricidia sepium sur la croissance de Adansonia digitata et de Sclerocarya birrea était mieux que celui de Albizia lebbeck et la bouse de vache (P< 0,05). Le compost de biomasses feuillées de Gliricidia sepium est de très bonne qualité tandis que celui de Albizia lebbeck est d’assez bonne qualité. Les biomasses de ces deux légumineuses constituent donc un bon matériel pour le compostage. Ces résultats peuvent servir à améliorer la production végétale en agroforesterie

Spatial Dynamics And Risks Analysis Of Lowlands Degradation Potential Around Of Nakanbé-Dem Sub-Watershed In Center-Nord Of Burkina Faso (West Africa): Through Multi-Date Study And Satellite Tele-Analysis

Watershed degradation is a key issue for environmental change in the Sahel region and causes an unprecedented threat to the lowlands watershed and the livelihood of local people. This study analyzes the spatial dynamics and degradation risks of Nakanbé-Dem sub-watershed lowlands’potential. The study combines lowlands plants species assessment and digital processing. Lowlands spatio-temporal dynamics were assayed from landsat images of 1986, 1996, 2006 and 2016. Vegetation data and soil physical and chemical parameters allowed to characterize lowlands degradation states. Lowlands degradation risk assessment is based on flora analysis and remote sensing indices (Normalized Difference Vegetation Index, Normalized Difference Water Index, slope values and water accumulation zones). Spatio-temporal dynamics analysis between 1986 and 2016 showed a continuous degradation of Nakanbé-Dem lowlands potential. The coverage of farming land increased from 31 to 51% compared to the total lowland potential of 43320 ha. The riparian formations have decreased by 4.11% in the same period. As concerns the lowland beds, their coverage rate has continuously decreased from 24% in 1986 to 7.79% in 2016. The coverage rate of water bodies has not kept a linear evolution. It went from 2.27 to 2.62%, a slight increase of 0.35%. Soil and flora samples were taken from the three lowland geomorphological subunits: glacis, hillside and the central zone. Soil analyze concerned the following parameters: useful watercontent, saturation rate, carbon, nitrogen, potassium and bulk density. Flora parameters analyzed are: woody cover, density of regeneration individuals, tree density, quadratic diameter, tree height, ligneous plants species richness, herbaceous species richness. These different measurements have been taken on the glacis, hillside and central zone. Flora and soils analysis showed difference in lowlands topographic structures. Unlike hillside and glacis, their central zone is less degraded. It is characterized by an average specific richness of woody plants about 3.43% against 3.13 % for hillsides and 2. 44 % for glacis. Tree average density (129.29 in/ha), the number of trees large diameter (118. 55 in/ha) and woody cover (61.79 %) are higher in the central zone than on the hillsides and glacis. From Pedological aspects, central zone is characterized by a concentration great of organic matter (1.49%) (great rate of carbon and nitrogen) against 0.89 for glacis and 0.90 for hillsides. The useful water content (19.75 %) and the saturation rate (64.85) in the central zone are great. These values are low on the glacis (9.36 and 63,77) and hillsides (12.17 and 59.66).In the current context of persistent climatic pressure, the conquering of new farms will accelerate the growth of cropped acreages and increase the degradation risk of lowlands’ potential. Lowlands’ dynamic apprehension can serve as a basis of development and endogenous programs implementation to restore sub-watershed lowland’ potential

Burkina Faso : à l’école du local

International audienc

Burkina Faso : à l’école du local

International audienc