Abstract
A laboratory and field study was conducted on subsurface drip irrigation systems. In the first laboratory study, eight subsurface drip irrigation lines, available locally, were selected and a number of experiments were made to evaluate lines' hydraulic characteristics to insure their suitability for drip irrigation design requirements with high uniformity and optimum performance, for the purpose to select the best for field experiments. The second study involved field trials on mature date palm trees to study the effect of a subsurface drip irrigation system on the yield and water consumption of date palms, and to compare that with the traditional surface drip irrigation system. Experiments were conducted in the Alwatania Agricultural Project on 50 mature palm trees (17 years old) of the 'Helwa' type with 10 meters spacing between rows and between trees. A high efficiency subsurface line (Tec line) was used based on the results of the first study. Irrigation scheduling was made through a soil moisture sensing device to ensure enough soil water level in the soil. The experimental layout was installed during the 2001 season and measurements continued till the end of the 2008 season.
Results have indicated that there is an increase in the yield and a considerable saving in water compared to the conventional drip irrigation method. In addition there was a high increase in water use efficiency using the subsurface system. The subsurface systems prove to be durable and highly efficient for irrigating date palm trees.