Does supplemental irrigation enhance smallholder monsoon season rice yield? Evidence from Bangladesh

Irrigation is one pillar of the Green Revolution that drove dramatic agricultural productivity gains across Asia. In Bangladesh, irrigation uptake has been so significant that 97% of dry-season rice is now irrigated. While most Bangladesh monsoon rice is completely rainfed, supplementary irrigation is sometimes employed where late monsoon onset is potentially yield-limiting. Station-controlled experiments provide a narrative of positive yield benefits from supplementary irrigation. In contrast, statistical evaluations of actual farm experience mostly show no yield benefit and lower profitability for supplementary irrigation adopters. To add evidence on this controversial practice, we evaluated data from 2012 and 2015 Bangladesh farm household surveys with causality econometric approaches that control for differences between supplementary irrigation adopter and non-adopter groups. After controlling for self-selection and endogeneity, we found no statistically significant yield benefit for supplementary irrigation. Our results support scepticism about the profitability of supplementary irrigation. As such, we recommend careful consideration of the mixed evidence on effectiveness in future supplementary irrigation project benefit cost analyses. Further evidence over a longer time and accounting for a broader range of crops is also important moving forward.