Irrigation solutions
Fertigation in Kenya
Fertigation is feeding the crop through the water line — water-soluble fertiliser delivered with the drip irrigation to the root zone. It's the standard method for greenhouse production and a serious efficiency upgrade in the field. Here's how it works, what it needs, and the rules that keep it safe.
What fertigation is
Fertigation combines fertiliser application with irrigation: a measured amount of water-soluble fertiliser is injected into the irrigation supply after filtration, and the crop receives water and nutrients together, at the root zone. Because fertiliser goes exactly where the water goes, use efficiency improves compared with broadcasting or side-dressing — the plant takes it up with its next water uptake, and there's less left in the field for rain or runoff to carry away.
In Kenya, fertigation is the default for greenhouse production (the media in bags and raised beds holds limited nutrients, so the crop is fed through the line over a long cycle) and an increasingly common upgrade for field vegetables, avocado, citrus and other orchard crops.
The equipment
| Component | Role | Notes |
|---|---|---|
| Fertigation tank(s) | Hold the mixed fertiliser solution | Typically 1–3 tanks (e.g. NPK + micro/magnesium + acid); sized to the crop's per-cycle volume |
| Injection point | Where the solution enters the irrigation line | Always after the filter, before the field; with a valve so it can be isolated |
| Injection method | Delivers the solution at the right rate | Pressure-driven venturi, injection pump (diaphragm) or dosing unit — matched to flow and budget |
| Tank mixing | Keeps the solution uniform | Many fertilisers settle; mechanical or air mixing where the tank isn't used up in one go |
| Flush line | Clears the injection line after feeding | Prevents precipitate building up in the fertigation plumbing |
The drip system itself does the distribution; fertigation is the head-assembly addition. See irrigation products for the components, and our design service specs the whole head — filter, injection, tanks, valves — as one unit.
Which fertilisers can you fertigate
Only water-soluble fertilisers. In practice: NPK water-soluble grades (e.g. 15-15-15, 20-20-20, 13-0-45), monoammonium phosphate, potassium nitrate, calcium nitrate, magnesium sulphate, and soluble micro mixes. They are mixed according to the crop's stage — a young tomato and a fruiting tomato need different ratios — and the tank schedule follows the agronomy plan, not the fertiliser bag.
What you can't do: use granular or slow-release products (they don't dissolve, they block the line), and you must respect chemical compatibility. Some fertiliser pairs precipitate when they meet in solution or in the pipe (the classic case is calcium products with sulphates or phosphates). The rules: keep incompatible products in separate tanks or separate application times, acidify only where the program calls for it, and never store a mixed tank for longer than the program assumes. The fertigation guide has the compatibility detail.
Safety and handling
- Handle chemicals as chemicals. Gloves and eye protection when mixing; store away from the crop storage area; label every tank with contents and date.
- Never inject a solution you can't flush. The injection line gets flushed with clean water after each feeding — a short run that clears the plumbing.
- Water quality still matters. Fertigation doesn't replace filtration — it adds a reason to keep the filter clean, because a blocked system mid-feeding is a fertiliser bill on the floor.
- Keep records. What went in, when, at what rate. The next grower (or you, three months later) will be grateful, and it's the only way to know if the program is working.
Where fertigation fits
- Greenhouses — essential; the crop is fed through the line for the whole cycle.
- Intensive field vegetables — tomatoes, capsicum, cucumber are the classic cases: long cycles, high fertiliser input, per-plant feeding makes sense.
- Orchards — avocado, citrus, mango: match feeding to the growth cycle (flush, flowering, fruit fill) and apply at the root zone where the roots actually are.
- Seedling production — light, frequent feeds; the most unforgiving place to get concentrations wrong.
Getting fertigation designed in
Fertigation is a head-assembly decision — it's cheapest and cleanest when it's in the original design, because the injection point, tank placement, flushing and pipe routing all depend on it. Adding it later is possible (we do retrofits), but it's always more work than designing it in. Mention fertigation in the quote request and the design will account for it.
FAQ
Fertigation questions
What is the simplest way to start fertigating?
One tank, one injection point after the filter, and a basic pressure-driven injector on a drip system that already has a valve you can isolate the fertigation line through. Feed a single NPK solution at the crop's stage-appropriate rate, flush the line after feeding, and keep records. Add tanks and a dosing pump when the crop program needs more than one product stream — see the fertigation guide.
Can I use any fertiliser for fertigation?
No — only water-soluble fertilisers, and with attention to compatibility between products (some pairs precipitate and will clog the system). Granular, urea and most slow-release products are out. The fertigation guide lists what works and the compatibility rules.
Do I need fertigation for field vegetables?
It's optional in the field and worthwhile on long-cycle, high-input crops — tomatoes, capsicum, cucumber — where the fertiliser bill is significant and per-plant feeding saves labour and improves use. For short-cycle leafy crops on well-managed soil, broadcasting or side-dressing can still be the right answer. The crop pages say what each crop typically needs.
What size fertigation tank do I need?
The tank should hold the fertiliser volume for at least one irrigation cycle (ideally a few cycles). That comes from the crop's fertiliser rate, the system's water volume per cycle, and the injection ratio — all of which are in the design. As a rough feel: small systems might use 20–50L tanks; commercial blocks 200L+. Send your system size and crop for a specific answer via the quote form.
Does fertigation clog drip lines faster?
Done properly, no — fertigated systems are typically well filtered precisely because the stakes are higher. The clog risks come from incompatible chemicals mixing, under-dissolved product, or a dirty injection line that never gets flushed. Follow the compatibility rules and the flush routine and the risk is low: see filtration and the line cleaning guide.
Design fertigation into your system
Tell us your crop and current setup — we'll spec the tanks, injection and valves to match.