Sub-soil irrigation involves watering in the root zone up to about 22.5 cm below the ground.
It results in huge savings on water, fertilizers and pesticides, and improvement in growth and yield has been clearly evident.
The instrument used for the purposes is known as a subsoil injector. It is an enlarged version of a medical syringe, operated by foot. It is fed from a 20-litre cane carried either on the operator’s back or on a vehicle. It is easy to use.
The needle is placed near the plant or seedling at an angle of about 45° and pushed into the ground in one movement. The pedal is then pressed with the foot. This operates a piston that forces out up to a litre of water at a depth of 22.5 cms, the ideal depth for optimum utilization.
In this system, evaporation losses are completely checked. It encourages deep roots, which act as a safeguard against subsequent droughts. This can also be used for injecting pesticides, fungicides and fertilizers. Besides, weeds are reduced as the surface is not wetted. This system is becoming increasingly popular for fruits and forestry plantation.