The rapid expansion of cities in sub-Saharan Africa generates increasing volumes of diversified organic wastes that require management and a high population need for local and fresh vegetables. Linking the different sources of organic materials generated in these cities with the needs of local food producers for fertilizers prepared from recycled organic materials is challenging. This requires that producers obtain the results they expect from the organic materials they recycle. Thus, recycling these organic materials in their raw form or after composting presents an opportunity for periurban agriculture, although the great variability in the quantity and quality of these materials raises questions about the consistency between their agronomic value and their economic value. In two large cities of Cameroon (Yaoundé and Bafoussam), different types of organic materials were sampled: unprocessed livestock waste and composts from manure or municipal solid waste. From an agronomic perspective, we calculated the fertilization value based on the nutrient (nitrogen, phosphorus, and potassium) content of the organic materials. From an economic perspective, we calculated the value based on the nutrient content of the organic materials and their substitution unit prices and recorded the current market price. This is the first time that this combined approach has been used in sub-Saharan Africa. Our results showed considerable variability and discrepancy in both the agronomic and the economic values. The market prices overvalued the urban composts by a factor of 6, while chicken feces were undervalued by a factor of 3. The unprocessed organic materials were the most interesting from an economic and agronomic perspective. Our findings suggest that (i) the composting process needs to be improved and (ii) the humus potential should be calculated to better assess the amendment value of organic materials and as a basis for adjusting their market price.

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垃圾现金：喀麦隆用作肥料的城市有机材料的农业经济价值评估

撒哈拉以南非洲城市的快速扩张产生了越来越多的多样化有机废物，这些废物需要管理，并且对本地和新鲜蔬菜的人口需求很高。将这些城市产生的不同有机材料的来源与当地食品生产商对由回收的有机材料制成的肥料的需求联系起来是具有挑战性的。这就要求生产者从回收的有机材料中获得他们期望的结果。因此，将这些有机材料以其原始形式或堆肥后的回收利用为城郊农业提供了机会，尽管这些材料的数量和质量的巨大差异引发了人们对其农艺价值与经济价值之间一致性的质疑。在喀麦隆的两个大城市（雅温得和Bafoussam），对不同类型的有机材料进行了采样：未处理的牲畜废物以及粪便或城市固体废物产生的堆肥。从农艺角度出发，我们根据有机物质的营养素（氮，磷和钾）含量计算了施肥值。从经济角度出发，我们根据有机材料的营养成分及其替代物的单价计算其价值，并记录当前的市场价格。这是在撒哈拉以南非洲首次采用这种综合方法。我们的结果表明，农艺价值和经济价值存在很大的差异和差异。市场价格将城市堆肥高估了6倍，而鸡粪却低估了3倍。从经济和农学角度看，未加工的有机材料是最有趣的。我们的发现表明，（i）需要改进堆肥过程，（ii）应该计算腐殖质潜力，以更好地评估有机材料的修正价值，并以此作为调整其市场价格的基础。