Summary Developing and promoting farming systems that make use of conservation tillage practices (minimum tillage, zero tillage) in combination with the retention of crop residues is a strategy being pursued by many national and international research organisations. This report describes a targeted modelling study that was implemented to explore the extent to which partial retention of residues might provide a way forward. The results of the study will contribute to the debate on the potential and limitations of the conservation agriculture concept in semi-arid tropical environments, particularly in drier, lower productivity areas.