Thirty years of agronomy research for development in irrigated rice-based cropping systems in the West African Sahel: Achievements and perspectives

Rice (Oryza spp.) is an important food crop and plays an essential role in food security in the Sahel region in West Africa. The Africa Rice Center (AfricaRice) Regional Station for the Sahel was established in 1976 to respond to the demand for increased domestic production through research for development (R4D). This paper aims to review 30 years of rice agronomy R4D in this region and provide perspectives for future research. Rice is mainly grown by smallholders in irrigated systems in the Sahel, where productivity is higher than in other African regions. However, there is still a large gap between potential yield and actual yield obtained by farmers, due to various factors including sub-optimal crop management (e.g. nutrient, weed, water management) and abiotic stresses (e.g. extreme temperatures, salt-affected soils). AfricaRice has developed crop simulation models, integrated crop management practices, water-saving technologies, agronomic interventions alongside salt-tolerant varieties, and decision-support tools for field-specific nutrient management (e.g. “RiceAdvice”). While evaluation of agronomic options is well covered in the literature, there is limited information on scaling and impact in terms of improved smallholder livelihoods. While results from long-term soil fertility trials show that double-cropping rice with appropriate fertilizer application can be sustainable, models that integrate climate change indicate a huge risk of yield reduction due to heat stress, especially in the dry season, unless adaptations such as change in sowing date and varietal improvement are applied. There has been limited research on farming systems beyond plot-level agronomy, and less focus on environmental and social sustainability than economic sustainability (i.e. yield and profit). Further R4D efforts are needed to scale out and scale-up agronomic options for enhancing the productivity and sustainability of irrigated rice-based cropping systems in the Sahel in the context of increasing competition for water, land, and labor under increasingly extreme weather conditions. Digital approaches such as the decision support tool “RiceAdvice” could play an important role in out-scaling of productive, profitable, and sustainable agronomic option