Water uptake by date palm on Haplic Luvisols in the Djibouti coastal plain

International audienceDate palm tree (Phoenix dactylifera L.) has been cultivated since Anquity under arid and semi-arid climates. This symbolic oasis plant is an important resource for valuing water resources in harsh environments. The Djibouti Republic sustains the expansion of date palm cultivation as a way to settle nomad populations and fight hunger but lacks local references on date palm tree water requirements. This paper establishes the first set of reference data on date palm tree water uptake under the pedoclimatic conditions of Djibouti using an original setup. Date palm tree water uptake was estimated by modelling a succession of 3 infiltration-redistribution experiments, first in the presence of the palm tree, then under bare soil condition, and finally with a no-flow condition at the soil surface. The no surface flow (internal drainage) experiment allowed estimating soil hydraulic parameters, which were then used to simulate the other two experiments including soil evaporation or palm tree evapotranspiration, respectively. Actual evapotranspiration was estimated to 5.6 mm/d between February and April that is during the mild season in Djibouti (25–28 °C). The corresponding daily water uptake was 60 L/d/tree. Daily irrigation need was calculated as 125 L/d/tree assuming a leaching fraction of 40%, which is 4 times smaller than current recommendations. However, calculated daily irrigation need reached nearly 300 L/d/tree in the hot season. Additional studies are needed to confirm this estimation. Reducing the irrigation doses currently in use could lead to precious water savings, given the high pressure put on water resources in the Djibouti district