the technology utilizes 2 times less irrigation water than drip irrigation,
while raising yields 3 to 5 times more; and ensuring water is not lost through evaporation.
Developed by Chahbani Technologies of Tunisia, the buried diffuser technology comes in three forms for use in irrigating trees, vegetables, and container plants. In Tunisia, Algeria, Morocco, Qatar, United Arab Emirates, Greece, California, and France, it’s being used to irrigate trees like olive, date palm, fig citrus, pistachio, almond, peach, and grape, plus vegetables, according to the buried diffuser innovator, and founder of Chahbani Technologies, Dr Bellachheb Chahbani.
The buried diffuser typically consists of a 6 millimeter diameter flexible tube connected to a 16 to 20 millimeter diameter polyethylene high-density (PEHD) pipe, connected to the diffusing material, at the bottom. The whole buried diffuser set up is then buried in holes below the topographic soil surface, next to the roots of trees and plants, needing irrigation. Only the distribution water pipe that connects to the main reservoir and the flexible tube is visible on the ground.
For trees when buried, its positioned 50 to 70 centimeters from the tree axis, while for shrubs, and medicinal or ornamental herbs its installed 20 centimeters away from the plant axis. Size dictates the purpose of each buried diffuser, those for irrigating trees, herbs, and plants have different sizes. For herbs, and medicinal and ornamental shrubs, diffusers are placed in holes 20 to 40 centimeters deep, while for trees they are typically placed 50 to 60 centimeters into the soil.
According to Dr Chahbani buried diffusers can be added to growing trees and plants or those freshly planted. Where they are added to already growing trees, they are placed on holes on the edge of the canopy of the tree or shrub, where roots spread out. A hole for a shrub or tree can be circular or squared but with a depth of 60 centimeters. The diameter of a circular hole ranges from 35 to 40 centimeters, while the dimensions of the square hole, are 40 by 50 centimeters.
The buried diffuser is placed between trees spaced 3 meters apart, but if the space exceeds 4 meters, two diffusers are required, and also if the canopy diameter is less than 2 meters. If the tree canopy diameter is between 2 to 4 meters, 3 diffusers are required.
To irrigate, water comes from the reservoir through a 16 to 20 millimeter distribution pipe into the flexible tube with a regulator on it. The regulator allows water to flow at rates 2, 4, and 8 liters per hour. Through the PEHD pipe, the regulated water is moved to the diffusing material, made of very porous plastic net, with 5 millimeter siliceous granulate. The water gets into these granulates and circulates through the macro pores, and infiltrates into the roots in soil below and along, the diffuser surface.
By using the buried diffuser technology, farmers can reduce their on farm production costs by up to 30 percent. Unlike most irrigation methods where energy is needed to pump water, this technology utilizes gravity and conventional water pressure to irrigate plants and trees.
As a result farmers save costs on energy for irrigating their trees, shrubs, herbs, and vegetables. After being installed, one buried diffuser can last for over 30 years without requiring maintenance.
Irrigation is the largest water consumer in Tunisia, using 80 percent of the country’s water resources according to the agriculture ministry. This amount of water helps produce 30 to 40 percent of the country’s overall agricultural production though the country is water scarce.
“As a researcher I have to find solutions to water scarcity, drought and adaptation to climate change,” said Dr Chahbani
who first researched on the buried diffuser in 1990, until it became available for use in 2014.