Combining user involvement with innovative design to develop a radical new method for managing N fertilization

In France, a single science-based model has dominated winter wheat N fertilizer management for 40 years. Despite scientific progress, it remains challenging to minimize N losses whilst maximizing grain yield and achieving satisfactory grain protein content. A mismatch between the science-based method and its implementation has been demonstrated. We thought that involving users early in the design process would lead to explore more relevant methods regarding the diversity of N issues and implementation conditions. We used a three-step design process: (1) a diagnosis of the uses of existing methods and tools, (2) a design process combining participatory workshops, generation of new knowledge and model-based prototyping, and (3) a test of the prototype in the users' conditions. We identified the fixing of a target yield a priori as one of the major problems with the current N fertilization method. We thus established an exploratory conceptual axis: a fertilization method without target yield. Design workshops led to a new method based on (1) the regular monitoring of crop N nutrition, (2) the acceptance of periods of crop N deficiency, and (3) the simulation of short-term soil N availability with a crop model. New knowledge was generated, and the Azodyn model was used to build decision rules for N applications, based on viability theory. The prototype was tested by two groups of farmers. We show that, by combining the three steps used here, it was possible to develop an innovative fertilizer method radically different from the dominant paradigm, and positively received by users.