In order to conserve soil fertility and to produce enough organic fertilizer and forage, farmers must manage efficiently the crop residues and animal waste produced on the farm. This article characterizes the local technical knowledge on organic fertilizer and the diversity of practices, and analyzes the efficiency of these practices. An agricultural survey was carried out in 2006 for villages in southern Mali. Farmers' local technical knowledge was characterized beforehand by an original method. Crop residues and animal waste management practices, as well as the production and use of organic fertilizer, were followed and measured. The efficiency of each practice was evaluated considering the output/input ratio for biomass, carbon and nitrogen. Farmers identified five types of organic fertilizers with different characteristics, uses, and types of risks. The use rate of crop residues and animal waste into organic fertilizer and the nitrogen and carbon efficiency were correlated with the development of diversified and innovative practices of crop residues and animal waste management. The nitrogen efficiency depended on the use rate of animal waste, but efficiencies remained low (<0.15 for C and <0.37 for N) and significant losses persisted.