Evaluating Supplementary Irrigation Depths for the Improvement of Water Productivity and Rice Yield in Semi-arid Climate, Eastern Burkina Faso

In Burkina Faso, supplementary irrigation is promoted as a strategy to overcome the uncertainty of rain and increase sustainably rain-fed rice yield. However, in the actual water scarcity context and the decline of rain water, high productivity cannot be achieved regardless to water use efficiency. Therefore, an experiment was conducted to identify optimal supplemental water depth that increases both water productivity and water savings while minimizing yield losses. Four replications of a randomized block design were implemented and three supplemental water depths of D5cm, D7.5cm and D10cm were field-evaluated against farmer’s irrigation water depth (FIWD). In D5cm, D7.5cm and D10cm treatments, water was applied once a week in case of no rain. In FIWD treatment, irrigation was supplied daily excluding the day of rain. The results revealed that water stress duration and amplitude increased with the decrease of water depth. Severe, moderate and low water stress were recorder in D5cm, D7.5cm and D10cm respectively while no stress was registered in FIWD. The severe water stress induced by D5cm diminished plant height, and the number of tillers by 11% to 3% respectively; while slight (D10cm) and moderate (D7.5cm) stress did not affect the growth. Comparable yield was obtained in D7.5cm (3.130 tha-1) and FIWD (3.279 tha-1). The application of 7.5cm of water yielded the highest gain of water saving (438 m3kg-1). We argue that the weekly supply of 7.5cm water depth can be suggested as a sustainable practice in semi-arid regions.