Subsurface drip irrigation performance for young date palm irrigation
In oasis areas, surface water resources are becoming increasingly scarce. Groundwater resources are often overexploited, and are of poor quality for their high salinity degree. Water conservation and economy have therefore become imperative for better oases durability. If localized irrigation is currently recommended in Morocco for saving water, its use in the sub-desert areas does not keep water safe from high evaporation rates. An alternative to this system would be the use of subsurface drip irrigation. This technique is defined as an application of water under soil surface through drippers, which discharge water at generally similar rates as the surface drip irrigation. As subsurface drip irrigation is a newly introduced technique in Morocco, a better understanding in local conditions of the infiltration process around a buried source, and its impact on plant growth is necessarily required. This study aims to contribute to improving the efficiency of water use by testing the performance of subsurface drip irrigation system, especially in areas where water is a limited resource. The objectives of this research are performance evaluation in arid conditions of the subsurface drip irrigation system for young date palms compared to the surface drip, as well as determining the appropriate method of flow measurement for a buried dripper. In this context, an experimental plot was installed on a farm in the region of Erfoud (Errachidia Province, Southeast Morocco) to characterize the respective performances of surface and subsurface drip irrigation on young date palm. Flow measure-ment to calculate the uniformity of the application of water was done through two methods: a flow measurement of drippers above the surface and another one underground. The latter method has also helped us to estimate losses through evaporation for both irriga-tion techniques. In addition, in order to compare the effect of two irrigation modes, plants were identified at random for each type of irrigation to monitor certain agronomic parameters (cumulative numbers of palms and root development). Experimentation referred to a distribution uniformity of about 88 %; considered satisfactory for subsurface drip irrigation while it is around 80 % for the surface drip irrigation. The results also showed an increase in root development and in the number of leaves, as well as a substantial water savings due to lower evaporation losses compared to the classic drip irrigation. The results of this study showed that subsurface drip irrigation is an efficient technique, which allows sustainable irrigation in arid areas.
Keywords: Subsurface drip irrigation, water conservation, arid areas, young date palms.