A conceptual Decision Support System (DSS) for organic N management was developed based on information on residue quality N-mineralization relationships. The current paper aims at validating the DSS using data obtained in sub-Saharan Africa on biomass transfer systems with maize. The percentage fertilizer equivalency (% FE) values of the organic resources increased linearly with their N content above a minimum of 2.3% N. For resources with high polyphenol contents, the slope of the regression decreased and the critical N content increased to 2.8%. For manures, no clear relationship between their % FE and quality was observed. Medium quality materials are to be applied together with mineral N. Several cases are discussed in which added benefits as a result of positive interactions between medium quality organic resources and mineral N were generated. Finally, thought is given to the information needed to turn the DSS from a concept into a useful soil management tool.