The Effect of Dripper Discharge and Growth Medium on Wetting Distribution Patterns in Soilless Growth Media

Determining the wetting distribution pattern is essential for the proper design of drip irrigation systems. Identifying the pattern of wetting distribution enhances the efficiency of the irrigation system and water use. This study was conducted to determine the wetting distribution caused by a point source and compare it among different growth media as a factorial based on a completely randomized design with three replications. The first factor, the growth medium type, included 9 levels with a combination of zeolite, perlite and cocopeat; the second one consisted of the dripper discharge at three levels of 2, 3 and 4 liters per hour. The results showed that the effects of medium type and the interaction of the medium × dripper discharge on all measured quantities (volume of irrigation water, wetting diameter in 10 and 20 cm layers from the surface, maximum wetting area and wetting volume) were significant. The effect of the dripper discharge on all quantities except the maximum wetting area was significant too. The addition of 10% cocopeat to perlite had a positive effect on the wetting distribution pattern and increased the wetting volume by 79% at a discharge of 3 liters per hour; however, zeolite did not perform well, as compared to cocopeat, reducing the wetting volume by 30%. In general, the appropriate dripper discharge in all growth media was 3 liters per hour. The discharges of 2 and 3 liters per hour are suitable and cocopeat-perlite medium with a composition percentage of 20-80 led to forming a suitable wetting distribution pattern.