Fertigation Equipment for Organic Farms

Fertigation — delivering liquid nutrients through your drip irrigation system — is one of the most powerful techniques available to an organic farmer. Instead of mixing jeevamrutha in a drum and walking row by row with a watering can, you add it once to a tank, open a valve, and the irrigation run distributes it uniformly across every root zone on your farm. This guide covers the equipment you need, how to size it, and how to schedule organic liquid inputs safely without clogging your drippers.

Why Fertigation Matters for Organic Farms

Liquid organic inputs like jeevamrutha, panchagavya, amrutpani, and liquid vermicompost work best when applied in small, frequent doses directly to the root zone. Flood or furrow application loses significant microbial content to soil surface evaporation and UV exposure before the liquid reaches the roots. Fertigation through drip eliminates this loss, reduces input volume needed by 20–30%, and lets you time applications precisely around crop growth stages.

The equipment investment is modest — typically ₹1,500–6,000 beyond a basic drip system — and pays back within one season through reduced input labour and improved nutrient uptake.

What Are the Two Main Fertigation Injection Methods?

Venturi Injector

A venturi injector uses differential pressure created by a constriction in the water flow to draw liquid from an open tank into the drip mainline. There are no moving parts and no electricity required — the water flow itself does the work.

How it works: the injector is installed in a bypass loop off the mainline. Water diverted through the narrowing venturi tube creates suction on the inlet pipe, which draws the fertilizer solution up from the tank at a ratio of roughly 1:10 to 1:20 (one part input to 10–20 parts water, depending on flow rate and pressure). You control concentration by adjusting the bypass valve.

Cost: ₹800–2,500 depending on pipe diameter (16mm for small farms, 25mm or 32mm for larger systems).

Suitable for: farms up to 2 acres, liquid inputs with no large particle solids — strained jeevamrutha and panchagavya filtered through muslin.

Important: always install a check valve on the suction line to prevent back-siphoning of liquid into your water source. This is non-negotiable for borewell water.

Bypass Fertilizer Tank (Pressure Tank)

A pressure tank — also called a header tank or bypass tank — is a sealed vessel, typically 100–200 litres, installed in a bypass loop parallel to the mainline. Water enters the tank, picks up dissolved nutrients, and exits into the irrigation flow. No external suction required; the system pressure drives the nutrient solution into the stream.

Cost: ₹2,500–6,000 for a food-grade polyethylene or stainless-steel tank with inlet and outlet valves.

Suitable for: farms where input concentration must remain consistent, or where the input is slightly thicker than a venturi can handle cleanly.

Limitation: once the tank runs out of nutrient solution, the concentration drops — you cannot refill mid-run without stopping irrigation.

How Do You Size the Fertigation Tank for Your Farm?

Tank size depends on your farm area, your drip system’s flow rate, and the dose of input per irrigation run.

Step 1 — Calculate your drip system flow rate. For a 1-acre vegetable farm with 2 LPH drippers at 30cm spacing, total flow is typically 800–1,200 litres per hour.

Step 2 — Decide input dose. Standard jeevamrutha dose is 200 litres per acre per application. Diluted to a final ratio of 1:10, you inject 20 litres of concentrated jeevamrutha into the mainline per acre per run.

Step 3 — Match tank to dose. For a 1-acre farm using a venturi at 1:10 dilution, a 25-litre suction tank holds one full-dose application. A 50-litre tank gives two passes without refilling. For a bypass pressure tank, a 100-litre vessel is the practical minimum — smaller tanks create uneven concentration distribution across the irrigation run.

Rule of thumb: never fill the tank more than 80% to allow headspace for pressure equalization in a bypass tank, and to prevent overflow in a venturi suction setup.

How Do You Strain Organic Inputs Before Injection?

This is the single most important step most farmers skip. Jeevamrutha, panchagavya, and liquid vermicompost all contain fine fibrous or particulate matter that will clog drippers within a few irrigation runs if injected unfiltered.

Straining method: pour your liquid input through a double layer of clean muslin — or a 200-mesh nylon strainer bag — into the fertigation tank. Do not squeeze the bag; let it drain freely to avoid pushing solids through. Return the residue to the field as a topical soil amendment.

After every fertigation run, flush the entire drip system with plain water for 15–20 minutes to clear residue from laterals and drippers.

What Is the Organic Fertigation Schedule for Vegetable Crops?

Growth Stage	Input	Frequency	Dose per Acre
Transplanting week	Jeevamrutha	Once	200 litres
Vegetative (weeks 2–5)	Jeevamrutha	Every 10 days	200 litres
Pre-flowering	Panchagavya	Once	30 litres (diluted 1:10)
Fruiting	Liquid vermicompost	Every 14 days	50 litres
Late season	Jeevamrutha	Once	200 litres

Never fertigate and apply foliar sprays on the same day. Give the root zone inputs 48 hours to be absorbed before any foliar application.

How Do You Maintain Fertigation Equipment?

Clean the venturi injector inlet strainer after every use — it takes two minutes and prevents 90% of clogging problems. For a bypass tank, drain and rinse with plain water after each use; organic residue left in a sealed tank turns anaerobic within 24 hours and can damage subsequent crops if injected.

Inspect all bypass valves and check valves at the start of each season. Replace rubber seals every two years — hardened seals cause pressure leaks that reduce injection efficiency without obvious visible signs.