Cash for trash: an agro-economic value assessment of urban organic materials used as fertilizers in Cameroon

Abstract

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.

Subproductos agrícolas (cáscara de yuca y arroz) para compost como alternativa de valoración económica

“…En adición, también se ha considerado que el precio de mercado de un material orgánico utilizado en la agricultura depende de su valor potencial de fertilización, es decir, su contenido de NPK. En este caso, podría calcularse el valor del compost en base al contenido de N, P 2 O 5 y K 2 O de los materiales orgánicos utilizados como materia prima para su elaboración (Thuriès et al, 2019).…”

Assessing the Value of Organic Fertilizers from the Perspective of EU Farmers

“…Meanwhile, studies on the economic evaluation of organic fertilizers are less common. Kall et al [21] and Thuriès et al [22] used a deterministic approach to capture the monetary value of organic fertilizers. However, notably, the actual economic value of an organic fertilizer corresponds to a farm-specific substitution value.…”