Biotechnologie, Agronomie, Société et Environnement (Jan 2014)
Diversité de la qualité des engrais organiques produits par les paysans d'Afrique de l'Ouest : quelles conséquences sur les recommandations de fumure ?
Abstract
Diversity in the quality of organic manure produced on farms in West Africa: what impact on recommendations for the use of manure?. The maintenance of humus balance in cultivated soils is a guarantee of the sustainability of production systems. In West Africa, the advice regarding application of organic manure to fields remains unique and independent of the quality of organic manures available on farms. Some studies show that West African farms produce a diversity of organic manure. Should the advice for organic manure application be reformulated to reflect this diversity of farm-produced organic manure? We propose to analyze the diversity of organic manure produced on certain farms and estimate the optimal amount of organic fertilizer that should be applied to the fields to ensure the renewal of organic matter. The analysis distinguishes a great heterogeneity of farm-produced organic manure. Farm-produced manure with a high amendment value provides a reference for the quality of the manure, but this is also the case for farm-produced manure with an average quality and for farm-produced composts with a high or average amendment value. Depending on the quality of the manure, with these types of organic fertilizer, it would be necessary to apply between 2.4 and 5.1 t·ha-1 per year on sandy soils and 2.1 to 4.4 t·ha-1 per year for clay. Depending on the quality of the compost, it would be necessary to apply between 4.1 and 5.4 t·ha-1 per year for sandy soils and between 3.5 and 4.6 t·ha-1 per year for clay. Taking into account the heterogeneity of the quality of farm-produced organic manure, we can adapt the current technical advice to ensure a renewal of soil organic matter. However, the quantities of organic manure needed are beyond the current capacity of farms. It would be necessary to increase the amount of organic manure produced on farms, to improve its quality and to integrate other modes of soil fertility management at farm level.
