Adaptive On-Farm Evaluation of Resource Conserving Rice Cultivation Practices in the Middle Senegal River Valley.

Sahelian rice production is often critiqued as sub-optimally yielding, resource and cost inefficient. Now practiced in six Sahelian countries, the System of Rice Intensification (SRI) has been proposed as an alternative to conventional techniques. Principles include single, young transplants, wide spacing, compost, mechanical weed control with a push weeder, and intermittent irrigation. We report on three seasons (2008 Dry and 2009 Dry and Wet Seasons) of on-farm experiments in three locations in the Senegal River Valley. In 2008, farmers’ (FP) and recommended management practices (RMP) were compared with a locally adapted version of SRI (ASRI), which substituted compost with mineral fertilizer. Across sites, we found significant yield increases for RMP (+20%) and ASRI (+31%) relative to FP. But while farmers appreciated these benefits, they also found ASRI labor demanding. Farmers subsequently designed and implemented a fourth system hybridizing RMP and ASRI (hereafter “Hybrid”), by maintaining intermittent irrigation, increasing crop density and following ASRI weeding with localized herbicide applications. RMP, ASRI and Hybrid yields were 25%, 25% and 19% more than FP in the second season. The Hybrid approach reduced labor requirements, giving the highest profits in 2 of 3 sites. In the final season, the Senegalese State halted herbicide subsidies. RMP, ASRI and Hybrid yields were 36%, 37% and 34% greater than FP. The Hybrid system reduced herbicide use by 38% and 75% compared to FP and RMP, and was the most profitable system across sites. Modeling the potential economic outcome of water savings reinforces these results, although scaling-up to the irrigation system level highlights constraints related to common-pool resource management and farmers’ level of social cohesion. We underscore that rather than rigidly comparing pre-defined cropping systems, greater emphasis should be placed on experimentally integrating farmers’ efforts to learn from and adapt farming practices to local socioeconomic and biophysical circumstances.