Sensitivity of southern African maize yields to the 1 definition of sowing dekad in a changing climate

Most African countries struggle with food production and food security. 6 These issues are expected to be even more severe in the face of climate change. Our 7 study examines the likely impacts of climate change on agriculture with a view to 8 propose directions to adapt especially in regions where it might be crucial. 9 We use a crop model to evaluate the impact of various sowing decisions on the 10 water satisfaction index and thus the yield of maize crop. The crop model is run for 176 11 stations over southern Africa, subject to climate scenarios downscaled from 6 GCMs. 12 The sensitivity of these evaluations is analysed so as to distinguish the contributions 13 of sowing decisions to yield variation. 14 We present results of the water satisfaction index average change from a 20 year 15 control period before 2000 and a 20 year period surrounding 2050 over southern Africa. 16 These results highlight some areas that will likely be affected by climate change over the 17 study region. We then calculate the sowing decisions contributions to yield variation, 18 first for the control period, then for the future period. The sensitivities computed 19 allow us to distinguish efficient decision to be adapted and long term efficiency of 20 corresponding adaptation options. In most of the studied countries rainfall expected in 21 the sowing dekad is shown to contribute more significantly to the yield variation and 22 appears as a long term efficient decision to adapt. We eventually discuss these results 23 and an additional perspective in order to locally propose adaptation directions. 24