Abstract
In the Sudano-Sahelian zone of West Africa, agricultural productivity is strongly affected by climate variability and change. Agricultural production is dominated by rainfed cereal production such as maize, millet and sorghum for food consumption. Farmers have small and variable yields, leading to increasing uncertainty about their ability to produce more to feed a rapidly growing population. The aim of this thesis was to design more productive and stable cropping systems, adapted to climate change, by exploring the benefits of sorghum-cowpea intercropping, combined with contrasting choices of sorghum variety, mineral fertilisation and sowing date. The approach was based on a survey, field experimentation and simulation using a crop model, for a case study in central Mali in West Africa. The first step was to identify farmers' perceptions of climate change and the agricultural adaptation strategies they consider relevant to cope with climate variability and change. Secondly, the STICS crop model was calibrated on the basis of two years of experimentation (2017, 2018) of the sorghum-cowpea intercrop at the N'Tarla agronomic station. In this experimental set-up, two sorghum varieties (local and improved) with contrasting sensitivity to photoperiod were studied in sole crops and in intercropping with cowpea. Two sowing dates and two levels of mineral fertilisation were also studied. The relevance of the model to represent competition and complementarities between sorghum and cowpea fo water and nitrogen use was evaluated. Finally, the performance (average productivity and productivity stability of a range of technical options for integrated soil fertility management.