Increase in rice productivity in the Senegal River valley due to improved collective management of irrigation schemes

Village irrigation schemes cover about 25% of the irrigated area on the two banks of the Senegal River. We analyzed irrigation scheme and rice crop management practices during the 1998 wet season in this type of irrigation scheme in Mauritania. Average yield was 4.8 t ha–1; problems with irrigation rules resulted in great variability of irrigation frequency between fields, and sub-optimal timing of nitrogen fertilizer application resulted in yield losses. Based on this diagnosis, we suggested to farmers new irrigation rules and cropping calendars planned on the scale of the irrigation scheme. Planned cropping calendars were built using CalCul, a software that we designed on the basis of the irrigated rice development model RIDEV. These suggestions of improved collective management were implemented in the 1999 and 2000 wet seasons. Average yield reached 7.2 t ha–1 in 1999 and 8.2 t ha–1 in 2000, without any significant increase in production costs. This great increase in rice productivity was mainly due to better collective management obtained through planning cropping calendars. This result showed that technical innovation is not the only way to improve productivity