Indicators for sustainability are a hot and debated topic. Sustainable intensification of agriculture is also widely debated due to the divergent views on the future of agriculture and the wide variety of indicators used. Legumes are seen as a key option for sustainable intensification of smallholder farming systems in sub-Saharan Africa (SSA). We developed a framework for assessing the sustainability of contrasting farming systems to illustrate the complex balancing act involved, using a case study of the N2Africa project. N2Africa offers legume options to farmers in SSA (www.N2Africa.org). We worked at farm household level and used a hierarchical framework of principles and criteria to select the indicators for sustainability.
One of the main outcomes is a list of questions and hurdles we ran into when developing the framework. This can be used by others as guidance both when choosing indicators and to critically evaluate existing sustainability assessments. We illustrate that many of the decisions made in developing an indicator framework are subjective and that they include important but easily overlooked details. We conclude that, only by being explicit about the steps taken and the assumptions and decisions made, one can develop a sustainability framework that results in meaningful outcomes.