Fertigation Calculator & Feed Through the Drip
Doses fertilizer for drip
Spoon-feed your crop through the drip — split a fertilizer dose across fertigation events and get the amount per event, the safe in-line concentration (g/L), and the stock-tank strength for your injector.
Splits = number of fertigation events over the crop (e.g. weekly through the season). More frequent, smaller doses suit drip.
Split 40 kg of fertilizer into 6 fertigations of about 6.74 kg each (6.74 kg/acre per event).
Next: dissolve fully and inject in the middle of the irrigation, then flush the lines with clean water at the end to prevent clogging and salt build-up. Keep the line concentration in a safe band to avoid root scorch.
A planning aid — follow product solubility limits and your agronomist's nutrient schedule. Don't mix incompatible fertilizers in one tank.
Fertigation — key facts
- Per event
- total dose ÷ splits
- In-line concentration
- kg per event × 1000 ÷ water (L)
- Safe in-line strength
- < 2 g/L (under 3 g/L)
- Stock tank
- line g/L × injector ratio
- Splits (drip)
- often 8–20 per season
- Inject
- in the middle of the run
- Then
- flush lines with clean water
- Privacy
- Runs in your browser; nothing uploaded
Spoon-feed the crop, safely
Fertigation turns a season's fertilizer into many small, precise doses delivered with the irrigation water — which matches how a crop actually takes up nutrients and cuts the leaching that wastes broadcast fertilizer. The arithmetic is simple but easy to get wrong: take the dose, multiply by area for the total, divide by the number of splits for the per-event amount, then check the concentration it makes in the irrigation water so you don't burn roots with a too-salty solution.
This tool does all of that and adds the bit most calculators skip — the stock-tank strength. Because injectors add stock at a fixed ratio (say 1:100), the tank must be that many times stronger than the final in-line concentration. Get it right and every emitter delivers the same correct dose; get it wrong and you either starve the crop or clog the drippers. Inject in the middle of the run and flush with clean water afterwards, and keep incompatible fertilizers in separate tanks.
Dose every event
Split the season's fertilizer into equal, precise per-fertigation amounts.
Keep it safe
See the in-line g/L with a safe / watch / too-strong flag to protect roots.
Mix the stock tank
Get the exact stock-tank concentration for your injector ratio.
Plan the schedule
Visualise the split schedule across the season and budget the total fertilizer.
Frequently Asked Questions
How do I calculate fertigation dose per event?+
Multiply the fertilizer dose (kg/ha) by your area to get the total, then divide by the number of fertigation events (splits). For example 100 kg/ha over 1 ha in 5 splits is 20 kg per fertigation. This tool also gives the amount per acre per event.
What is fertigation?+
Fertigation is applying water-soluble fertilizer through the irrigation system — usually drip — so nutrients reach the root zone with the water. It improves nutrient-use efficiency, lets you spoon-feed the crop in small frequent doses, and saves labour over broadcasting.
What concentration of fertilizer is safe in the line?+
Keep the dilute, in-line concentration low — generally below about 2 g/L for routine fertigation, and under 3 g/L to avoid high salinity (EC) that can scorch roots. This tool flags the g/L and warns when it's getting too strong; if so, split into more events or use more water.
How do I make the stock solution?+
Dissolve the per-event fertilizer in a stock tank, then inject it into the irrigation at your injector's ratio (e.g. 1:100). The stock-tank concentration must be the line concentration multiplied by the ratio — so a 0.4 g/L line strength at 1:100 needs a 40 g/L stock. The tool computes this for you.
What is an injector ratio?+
Dosing pumps and venturi injectors add a fixed proportion of stock solution to the irrigation water — 1:100 means one litre of stock per 100 litres of water. A higher ratio means a more concentrated stock tank for the same final strength.
How many splits should I use?+
Drip crops are usually fertigated little and often — weekly or even every irrigation — so a season might have 8–20 splits. More frequent, smaller doses match nutrient uptake and reduce leaching; match the split count to your crop's nutrient schedule.
Can I mix different fertilizers in one tank?+
Only compatible ones — for example, calcium fertilizers must not be mixed with phosphates or sulphates in the same stock tank, or they precipitate and clog drippers. Use separate tanks for incompatible products and check solubility limits.
Should I flush the lines after fertigating?+
Yes — inject fertilizer in the middle third of the irrigation, then run clean water for the last 15–30 minutes to flush nutrients out of the laterals. This prevents salt build-up and algal/clogging problems at the emitters.
Does this replace a nutrient schedule?+
No — it handles the dosing arithmetic (per event, concentration, stock tank) once you know the dose and split count. The crop's nutrient requirement and timing should come from a soil test and an agronomist's fertigation schedule.
How is this different from the NPK calculator?+
The Fertilizer (NPK) Calculator converts a recommended dose into bags of urea/DAP/MOP for broadcasting. This fertigation tool takes a dose and tells you how to split and dissolve a water-soluble fertilizer for drip application. Use them together.