Supplemental Irrigation (SI) is a key strategy, still underused, for unlocking rainfed yield potential and water productivity (Rockström et al., 2010. SI is the addition of limited amounts of water to essentially rainfed crops to improve and stabilize yields when rainfall fails to provide sufficient moisture for normal plant growth. SI can take place in areas with unreliable rainfall or with periods of extreme heat. The timing of SI is again irrigation scheme and weather dependant. Either before planting (or ‘onset rainfall’), allowing farmers to plant their crop early or optimally scheduling it during the critical stages of crop growth (flowering and grain filling). SI is an effective response to alleviating the adverse effects of soil moisture stress on the yield of rainfed crops during dry spells. This in particular during critical crop growth stages, can improve crop yield and water productivity.

Additional sources Rockström, J., Hatibu, N., Oweis, T., Wani, S., Barron, J., Bruggeman, A., Qiang, Z., Farahani, J., & Karlberg, L. (2010). Managing Water in Rainfed Agriculture —The need for a paradigm shift. Agricultural Water Management. Volume 97, Issue 4, Pages 543-550.