Michael Bruentrup, and Andreas Buerkert
Nutrient Cycling in Agroecosystems


Low concentrations of phosphorus (P) also limit crop production on the acid, sandy soils in Sudano-Sahelian West Africa (SSWA). An increased P-use is thus a key leverage for enhancing food security and alleviating poverty. Therefore, P-imports into the predominating agro-pastoral farming systems are indispensable, but most smallholders are cash-poor and risk averse, face labor-constraints, and P-fertiliser responses are site-specific. Key to the adoption of any new technology is a high financial performance with low risk levels of failure, low demands of labor and cash, and adaptation to the prevailing farming systems. Financial performances were assessed from nine, annually applied fertilising practices during 4 years in five SSWA zones. Information about the farming systems, labor demands, and input–out-putprices stem from secondary sources. The profitability largely depended on rainfall and location-specific soil conditions, but those of annually repeated mineral and organic P-strategies increased over time. Several P-fertilisations were profitable on a per land unit basis, but could not compete with farmers’ practices on a per labor unit basis. Mulching with and without P(13 kg P ha-1) were not financially superior, but the broadcast application of 13 kg P ha-1 became profitable over time. Hill-placed P (4 kg P ha-1), also known as micro-dosing, was a profitable alternative to farmers’ practices particularly in the intermediate rainfall zone. The results showed the importance of recommendations following rainfall zones, which are of interest across a spectrum of users including policy makers, land use practitioners, private firms, NGOs and research for development implementers