Biofertilizer for Onion in India (2026): Seedling Dip, Dose per Acre and Cost for the Rabi Transplant

Short answer: for a rabi onion transplant, dip the seedling roots in Mycorrhiza VAM before planting, then give 1 litre of NPK Consortia per acre through drip or with the first irrigation. At Orgogrowth's current prices that is about ₹94 per acre for NPK Consortia (₹4,699 per 50 L drum, 1 L/acre), plus about ₹250 per acre for VAM powder (₹2,499 per 1 Kg pack at 100 g/acre) or ₹232–₹348 per acre for VAM Liquid (₹5,800 per 50 L drum at 2–3 L/acre). All prices include 5% GST and free delivery.

Onion has a thin, shallow root system with very few root hairs, so it struggles to reach phosphorus already locked in the soil. Mycorrhiza fungal threads do that reaching for it, and the best time to give it is at transplanting, not at bulb formation.

Why onion responds to mycorrhiza

Onion and other Allium crops are strongly mycorrhizal: their roots are unbranched and sparse, so they depend on fungal hyphae to explore soil. Mycorrhiza hyphae are roughly 2–5 micrometres across, against 10–15 micrometres for a root hair, and grow several centimetres beyond the root surface, into soil the onion root cannot reach by itself. This is why the benefit shows mainly as better phosphorus uptake and less transplant shock, rather than as a dramatic leaf-colour change. Colonisation takes 2–3 weeks, so applying late (at bulbing) is mostly wasted.

Rabi onion schedule (nursery to bulbing)

1. Nursery / seedlings (45–50 days old): Make a slurry of Mycorrhiza VAM Powder (6000 IP/gm) and dip the root bundles for 15–30 minutes before transplanting. Alternatively use Mycorrhiza VAM Liquid at 10 ml per litre of water for a 30-minute dip.
2. At transplanting or first irrigation: Apply NPK Consortia at 1 L per acre through drip or mixed with 100 kg of compost per acre. It carries Azotobacter chroococcum (nitrogen), Pseudomonas spp. (phosphate solubiliser) and Frateuria aurantia (potash mobiliser) at a minimum of 5×10⁸ cells/ml.
3. 25–30 days after transplanting: Repeat 1 L per acre of NPK Consortia with irrigation. Keep the chemical fertiliser dose reduced (the label basis is 25–30% less NPK) rather than cutting it to zero in the first season.
4. Do not apply fungicides in the same window: keep a 7–10 day gap between chemical fungicides (Carbendazim, Mancozeb) and mycorrhiza, and drench the nursery fungicide treatment before, not after, the VAM dip.

Cost per acre

With two 1 L/acre passes of NPK Consortia (₹188) and a VAM seedling dip using the powder (₹250), the biological input comes to roughly ₹438 per acre per season. Phosphate fertiliser (DAP/SSP) typically costs ₹4,000–₹6,000 per acre per season, and the VAM label basis is a 40–60% reduction in P-fertiliser need, so the arithmetic favours trying it on at least a few acres first. Orders of 2 drums get 5% off and 3+ drums get 10% off, mixed across any Orgogrowth 50 L drums.

Keep it honest: what to expect

Biofertilizers do not replace a soil test. If your soil is already high in available phosphorus, the visible gain from mycorrhiza will be smaller. Test one plot with the treatment and one without, mark both, and compare bulb size at harvest before scaling to the whole farm.

FAQ

What is the dose of biofertilizer for onion per acre?

NPK Consortia 1 L per acre (drip or with compost), Mycorrhiza VAM Powder 100 g per acre or VAM Liquid 2–3 L per acre, applied at transplanting.

How much does it cost per acre?

About ₹94 per acre for one pass of NPK Consortia, ₹250 per acre for VAM powder, ₹232–₹348 per acre for VAM Liquid (incl. 5% GST).

When should I apply mycorrhiza on onion?

At transplanting, as a seedling root dip or first irrigation. Colonisation needs 2–3 weeks.

Can I mix it with fungicide?

No. Keep a 7–10 day gap from chemical fungicides.

Is it certified?

Orgogrowth biofertilizers comply with FCO 1985 and are made in an ISO 9001:2015 certified unit in Mehsana, Gujarat.