Fertilizer Injector & Rate & Flow
Doses dosing pumps
Enter target concentration, stock concentration and system flow to get the injection ratio and injector flowfor fertigation — so the line hits your target nutrient strength.
Fertigation injector rate
Next: set your injector to 100 L/h (dilution ratio 1:100); verify with a catch-can test and an EC meter on the emitter line.
Assumes a proportional injector and well-mixed stock. Always check pump capacity and back-flow prevention before injecting nutrients into a pressurised line.
Injector rate — key facts
- Injection ratio
- target ÷ stock
- Injector flow
- system flow × ratio
- Units
- same scale for both conc.
- Stock
- must be far stronger than target
- Typical range
- ≈ 1:50 to 1:500
- Field check
- EC meter at the emitter
- Proportional vs pump
- set ratio vs set flow
- Privacy
- Runs in your browser; nothing uploaded
From a strong stock tank to the right feed at the emitter
Fertigation only works if the injector meters concentrated stock into the line at exactly the right rate. Set it too rich and you scorch roots, waste fertiliser and risk clogging; set it too lean and the crop is underfed however good the recipe. The setting comes from two simple relationships: the injection ratio is your target concentration divided by the stock strength, and the injector flow is the system flow multiplied by that ratio.
This tool gives the injection ratio, the injector flow, the system flow and the target concentration so you can dial in a dosing pump, choose a venturi, or set a proportional injector directly. Use it to keep the feed on target across changing irrigation rates. Pair it with the Fertigation Stock Tank, Fertigation and Acid Injection tools, and the Drip System Flow calculator, for a complete fertigation setup.
Hit target strength
Set the ratio so the emitter feed is right.
Size the injector
Get the stock flow your device must deliver.
Avoid scorch
Keep the line from running too rich.
Match any device
Ratio for proportional, flow for dosing pumps.
Frequently Asked Questions
What does a fertilizer injector do?+
A fertigation injector — a dosing pump, proportional injector or venturi — meters concentrated stock solution into the irrigation line so the water reaching the crop carries nutrients at a target concentration. Setting it correctly is what turns a strong stock tank into the precise dilute feed the crop actually receives.
How is the injection ratio calculated?+
Injection ratio = target concentration ÷ stock concentration. If you want 200 ppm at the emitter from a stock that is 20,000 ppm, the ratio is 200 ÷ 20,000 = 1:100 — one part stock to 100 parts irrigation water. The stock must be far more concentrated than the target so the ratio stays in the injector's working range.
How do I get the injector flow?+
Injector flow = system flow × injection ratio. With a system flow of 1,000 L/h and a 1:100 ratio, the injector must deliver 1,000 × (1/100) = 10 L/h of stock. The tool returns this directly so you can dial in a dosing pump or pick a venturi sized to that flow at your line pressure.
What units should the concentrations be in?+
Target and stock concentration just need to be in the same units — ppm, mg/L, g/L or percent — because the ratio is dimensionless. Mixing units (say target in ppm, stock in percent) without converting is the most common mistake; convert both to one scale first and the ratio comes out right.
Why must the stock be much stronger than the target?+
The injection ratio equals target ÷ stock, and injectors only operate over a limited ratio range (often around 1:50 to 1:500). If the stock is only a little stronger than the target, the ratio is too high for the injector to deliver, and the stock tank empties almost as fast as the irrigation runs. A concentrated stock keeps the ratio practical.
Does the injector type change the setting?+
The required ratio and injector flow are the same regardless of device, but how you set them differs: proportional (water-driven) injectors are set as a ratio directly; electric dosing pumps are set by flow rate; venturis are chosen by their suction flow at your line pressure and flow. Use the ratio for proportional units and the injector flow for pumps.
How do I check the injector is dosing correctly?+
Measure the actual concentration at an emitter with an EC meter or by timing how much stock is drawn down over a known irrigation volume, and compare to your target. EC is the quickest field check for total salts; verify against the calculated ratio and adjust the setting if the measured strength drifts.
Can I use it for acid and pH dosing too?+
The same ratio and flow maths apply to any stock injected proportionally, including acid for pH or chlorine for line cleaning. For acids, work to a target dose rather than a nutrient ppm and always add acid to water, never the reverse — see the dedicated acid injection tool for safe rates.
Are the figures exact?+
The ratio and injector flow are exact arithmetic from your inputs. Real delivery depends on the injector's accuracy, line pressure, stock solubility and temperature, so verify in the field and re-check periodically. Treat the result as the correct setpoint and fine-tune to the measured concentration at the emitter.