Trickle irrigation (Drip irrigation)
With trickle irrigation water is delivered to the plants, drop by drop, via a set of plastic lateral tubes laid on
the ground or buried at a depth of 15-30cm, which are supplied from a head unit through a field main pipeline.
The laterals are commonly 15-25mm in diameter, and are either provided with emitters designed to drip
water onto the soil. By drip irrigation daily to twiceweekly, soil water in the root zone is kept about field
capacity (soil moisture tension of 0.3 to 0.5bar). Under these conditions, the emitter rate approaches closely
the actual crop evapotranspiration (ETcrop). The rate of emitters is generally in the range of 1 to 10 liter/hour,
(industrial crop about 1 to 3, orchards 3 to 10) and it do not exceed the basic infiltration rate. The operation
pressure is usually in the of 1 to 3 atmospheres. Under trickle irrigation, the wetted portion of the soil
is reduced, i.e., the active rooting volume is usually confined to a fraction (often less than 50 percent)
of what would be the normal root zone of an uniformly wetted soil. Consequently the water need for irrigation
is reduced by 50 percent or more compared to the above described irrigation methods.
With trickle irrigation, it is possible to use salty water (concentration about 1,000mg/liter salt).
Under optimal management conditions, yield increases from 20 to 50% are realistic, as well as high product value of 40 per cent or more per unit volume of water.