Fertigation Injection & How Long to Inject
Doses drip
Work out the stock-solution volume from the fertiliser need and stock concentration, then divide by the injector flow to get how long to inject — in minutes and hours. Dose the whole field evenly.
Plan your injection run
Next: mix 50 L of stock and run the injector at 50 L/h for 60 min; keep injecting only while irrigation water is flowing.
Inject into the middle of the irrigation set, then flush the lines with clear water before shutting down to avoid salt build-up at emitters.
Fertigation injection — key facts
- Stock volume
- fertiliser ÷ stock concentration
- Injection time
- stock volume ÷ injector flow
- Output
- minutes and hours
- Inject within
- the irrigation set, then flush
- Injector types
- Venturi, dosing pump, proportional
- Limit
- fertiliser solubility in stock
- Units
- keep mass and volume consistent
- Privacy
- Runs in your browser; nothing uploaded
Set the timer right and the field gets an even dose
Fertigation only works if the dose goes in at the right pace. Start from the fertiliser the crop needs and the strength of the stock you mixed: that fixes how many litres of stock carry the dose. Divide that volume by the rate your injector meters at, and you have the run time. Inject steadily over part of the irrigation set, then flush with clean water, and every emitter delivers a similar concentration instead of a slug up front and clear water after.
This tool gives the stock-solution volume and the injection time in minutes and hours from the fertiliser required, the stock concentration and the injector flow. Use it to set a controller, size the stock tank and make sure injection finishes with time to flush. Pair it with the Fertigation EC to PPM, Spreader Uniformity and Sulphur Nutrient tools for a complete fertigation plan.
Set the run time
Know exactly how long the injector should run.
Dose evenly
Inject steadily so every emitter gets the same strength.
Leave time to flush
Finish injection before the irrigation set ends.
Size the tank
See the stock volume the dose actually needs.
Frequently Asked Questions
How is the injection time calculated?+
In two steps. First the stock-solution volume = fertiliser required ÷ stock concentration, which is how much of your made-up stock contains the dose. Then injection time = stock volume ÷ injector flow rate. The tool reports the stock volume and the run time in both minutes and hours so you can set a timer or controller.
What is the stock solution?+
It is the concentrated fertiliser solution you mix in a tank and meter into the irrigation line. Its concentration — say grams of fertiliser per litre — sets how much solution carries the dose: a stronger stock means less volume to inject. Knowing the concentration is what lets the tool turn a fertiliser quantity into a volume and then a time.
What is the injector flow rate?+
It is how fast the injector or dosing pump pulls stock into the irrigation water, in litres per hour or per minute. A Venturi, a positive-displacement dosing pump or a proportional injector all have a flow you can set or measure. Dividing the stock volume by this flow gives the run time needed to inject the whole dose.
Why dose over a set time instead of all at once?+
Injecting steadily over part of the irrigation set spreads the nutrient evenly through the water and across the field, and lets you bracket it with clean water to flush the lines. A measured injection time is what keeps every emitter delivering a similar concentration rather than a slug at the start.
How do I pick the stock concentration?+
Mix to a concentration the fertiliser can fully dissolve at your water temperature and that your injector can handle without clogging — manufacturers quote solubility limits. A higher concentration shortens the injection time but risks precipitation; a lower one is safer but needs a bigger tank and longer run. Enter whatever you actually mixed.
Should injection finish before the irrigation does?+
Yes — inject within the irrigation set and leave time to flush, so clean water clears fertiliser from the pipes and emitters before shut-off. If the calculated injection time is longer than your irrigation run, either raise the injector flow, raise the stock concentration, or split the dose across more sets.
Does this work for any injector type?+
Yes. Venturi injectors, dosing pumps and proportional injectors all reduce to a flow rate, so as long as you enter the flow the stock is metered at, the time calculation holds. Proportional injectors meter as a ratio of water flow, so confirm the resulting stock flow at your irrigation rate before entering it.
What units should I enter?+
Keep them consistent: fertiliser required and stock concentration in the same mass basis (e.g. grams and grams per litre) so the stock volume comes out in litres, and the injector flow in litres per hour or minute. The tool then reports the stock volume in litres and the injection time in minutes and hours.
Are the figures precise?+
They are exact for the inputs, but real injection depends on a steady flow, a fully dissolved stock and no clogging. Calibrate the injector by timing a known volume, watch for precipitation in the tank, and check the line concentration on a long run. Use the result to set the timer, then verify on the ground.