Chapter 18

Fertigation Systems for Vineyards

Venturi Fertigation Injectors

The venturi injectors create a pressure differential that forms a vacuum. As water flows through the tapered venturi orifice, a rapid change in velocity occurs. This velocity change creates a reduced pressure (vacuum), which draws the liquid to be injected into the irrigation system, eliminating the need for a separate chemical injection pump. The injection rate of a venturi device is determined by the size of the venturi and the pressure differential between the inlet and outlet ports. The larger the pressure drop, the higher the injection rate, up to some maximum drop.

Advantages/Disadvantages of Venturi Injectors

Venturi Injector Configurations

There are three configurations used with venturi-type suction devices.

In the first venturi configuration, the injector may be plumbed in parallel with a simple, manually operated valve on the mainline circuit as shown in Figure 18.3. A valve in the mainline is used to provide the pressure drop needed to operate the injector. Partially closing the valve creates a pressure drop across the injector. Using a bypass setup, the injector can be turned off with a valve when injection is not occurring.

Click on the following topics for more information on fertigation systems for vineyards.