Evaluation of climate adaptation options for Sudano-Sahelian cropping systems

Abstract

In the Sudano-Sahelian region, smallholder agricultural production is dominated by rain-fed production of millet, sorghum and maize for food consumption and of cotton for the market. A major constraint for crop production is the amount of rainfall and its intra and inter-annual variability. We evaluated the effects of planting date on the yield of different varieties of four major crops (maize, millet, sorghum and cotton) over three contrasting growing seasons in 2009–2011 (with 842 mm, 1248 mm and 685 mm of rainfall respectively) with the aim of identifying climate adaptation options in the Sudano-Sahelian region. Three planting dates (early, medium, and late) and three varieties of long, medium, and short duration of each crop were compared. For fertilized cereal crops, maize out yielded millet and sorghum by respectively 57% and 45% across the three seasons. Analysis of 40 years of weather data indicates that this finding holds for the longer time periods than the length of this trial. Late planting resulted in significant yield decreases for maize, sorghum and cotton, but not for millet. However, a short duration variety of millet was better adapted for late planting. When the rainy season starts late, sorghum planting can be delayed from the beginning of June to early July without substantial reductions in grain yield. Cotton yield at early planting was 28% larger than yield at medium planting and late planting gave the lowest yield with all three varieties. For all four crops the largest stover yields were obtained with early planting and the longer planting was delayed, the less stover was produced. There was an interaction between planting date and variety for millet and sorghum, while for maize and cotton the best planting date was more affected by the weather conditions. The findings of this study can support simple adaptation decisions: priority should be given to planting cotton early; maize is the best option if fertilizer is available; planting of maize and sorghum can be delayed by up to a month without strong yield penalties; and millet should be planted last