Fertilizer Injection Rate

\[Q_i=\frac{Q_wC_t}{C_s}\]

Variables

Qifertilizer injection rate (L/h)

Qwirrigation water flow rate (L/h)

Cttarget nutrient concentration in irrigation water (g/L)

Csstock solution concentration (g/L)

Description

What is this formula?

The Fertilizer Injection Rate equation calculates the flow rate at which a concentrated fertilizer solution must be injected into an irrigation system to achieve a desired nutrient concentration.

When to use it

Use this formula when designing or operating fertigation systems, injector pumps, venturi injectors, and greenhouse irrigation systems.

Example

An irrigation system delivers:

Qw = 5000 L/h

Desired nutrient concentration:

Ct = 0.8 g/L

Stock solution concentration:

Cs = 100 g/L

Formula:

Qi = (Qw × Ct) / Cs

Substitution:

Qi = (5000 × 0.8) / 100

Qi = 40 L/h

Result:

The injector must deliver 40 L/h of fertilizer solution.

Applications

- Fertigation system design

- Venturi injector sizing

- Injector pump calibration

- Greenhouse irrigation

- Precision agriculture

Note

This equation assumes complete and uniform mixing of the fertilizer solution within the irrigation water. Real systems may experience slight variations due to injector performance, mixing efficiency, and hydraulic conditions.