Abstract:
Management practices that simultaneously enhance rice yield, water productivity, labor productivity, and grain
quality are needed for improving crop production and mitigating the negative impact of water scarcity on food
security. The objectives of this on-farm study were to evaluate the effects of water management practices
including the safe alternate wetting and drying (AWD) method of irrigation on rice yield, water productivity,
weed biomass, and grain quality, and identify the factors associated with their variabilities in the fields with
AWD. On-farm trials were conducted over two years in 30 fields within two irrigation schemes in the region of
Bouake, central Cote ˆ d’Ivoire. Before rice cultivation, in each field, three plots consisting of water management
practices were established: continuous flooding (CF), safe AWD, and farmers’ practice (FP). Lowland weeds were
dominant in rice fields in this study area. Large variations in weed biomass, rice yield, and water productivity
were found across fields for each water management practice. Weed biomass and irrigation water input were
lower under safe AWD than CF due to higher soil drying while there was no significant difference in rice yield
between safe AWD and CF. Water productivity was higher under safe AWD than CF and FP. Rice milling recovery, head yield, and chalkiness were not significantly different among water management practices. Higher
rice yield and water productivity in the safe AWD fields were associated with higher soil pH and nitrogen (N)
fertilizer rate and better congruence between nitrogen fertilizer application and crop N demand. Milling recovery, head yield, and chalkiness in the safe AWD fields were strongly affected by the choice of rice variety.
Combination of safe AWD with varieties having good grain quality characteristics and improved nutrient
management practices could be recommended to the smallholder rice farmers to improve rice yield, water
productivity, and grain quality and reduce labour requirement for irrigation and weeding particularly in schemes
where lowland weeds are dominant.
