Chapter 18

Fertigation Systems for Vineyards

Pressure Differential Tank Fertigation Injection

A pressure differential tank system operates on the principle that a pressure differential is created by a partially closed valve placed on the pipeline between the tank inlet and outlet (Figure 18.2). The pressure difference forces the water into a bypass pipe, where it enters a pressure tank containing the fertilizer. The irrigation water mixes with the fertilizer solution, and the dilution passes out of the tank into the downstream irrigation system. A metering device often controls the flow back into the main line. Care must be taken to ensure sufficient time is allowed for the fertilizer to dissolve and gradually move into the supply line. Most systems require about 40 to 90 minutes of injection time to adequately dissolve and flush out the lines. Fertigation delivery times can be checked using dye. When using fertilizers such as potassium nitrate or ammonium nitrate, nitrate test strips can be used to detect movement in the irrigation line.

Batch versus Differential Pressure Tanks

In fertigation, a batch tank (dilute tank control) and a differential pressure tank refer to two distinct methods of mixing and injecting fertilizers, primarily differing in their operational principles and the consistency of the fertilizer concentration.

Advantages/Disadvantages of Pressure Differential Tanks

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