Biofertilizer Dose Calculator & Rhizobium, Azotobacter & PSB
Doses Rhizobium
Dose your biofertilizer right — pick the culture and your area for the soil and seed-treatment dose, the FYM carrier, and the nitrogen it can save.
Enter your crop
Next: fixes n for pulses/legumes — apply it to moist soil near the root zone, or coat the seed and sow in the shade within a few hours.
Biofertilizers supplement, not fully replace, fertilizer; use before expiry.
Biofertilizer — key facts
- Soil dose
- ≈ 2 kg/acre (5 kg/ha)
- Seed treatment
- ≈ 20 g/kg seed
- FYM carrier
- ≈ 25–50 kg/acre
- Rhizobium
- for legumes (N fix)
- Azotobacter
- for cereals/veg (N fix)
- PSB / KMB
- free soil P / K
- Keep
- cool, shaded, before expiry
- Privacy
- Runs in your browser; nothing uploaded
Put soil microbes to work — for less fertiliser
Biofertilizers are living cultures of helpful microbes that fix nitrogen from the air or unlock phosphorus and potassium already in the soil — cutting your fertiliser bill and building soil health. But they're cheap inputs that are easy to misuse: the right culture for the crop, the right dose, mixed with FYM and applied to moist soil, makes all the difference between a real benefit and a wasted packet.
This tool gives the soil-application and seed-treatment dose, the FYM carrier, and the nitrogen saved for Rhizobium, Azotobacter, Azospirillum, PSB, KMB or Acetobacter on your area. Keep the culture cool and out of the sun, use it before expiry, don't mix it directly with chemical fertiliser or fungicide, and remember it supplements rather than replaces fertiliser. Pair it with the Fertilizer (NPK), Compost & Manure and Seed Treatment tools.
Dose it right
Soil and seed-treatment amounts for your crop and area.
Cut the urea
See the nitrogen an N-fixer can save you in fertiliser.
Apply correctly
FYM carrier and moist-soil application for live microbes.
Pick the culture
Match Rhizobium, Azotobacter, PSB or KMB to your need.
Frequently Asked Questions
How much biofertilizer per acre?+
Typically about 2 kg per acre (≈5 kg/ha) for soil application of most carrier-based biofertilizers, mixed with 25–50 kg of well-rotted FYM or compost and applied to moist soil. Seed treatment uses roughly 20 g per kg of seed. This tool gives both doses for your chosen biofertilizer and area.
What is a biofertilizer?+
A biofertilizer is a living culture of beneficial microbes — nitrogen-fixers like Rhizobium, Azotobacter and Azospirillum, or nutrient-mobilisers like PSB (phosphorus) and KMB (potassium) — that improve nutrient availability to crops. They supplement chemical fertiliser, cut input cost and improve soil health, but don't fully replace fertiliser.
Which biofertilizer should I use?+
Match it to the crop and need: Rhizobium for legumes/pulses (it fixes N in root nodules), Azotobacter or Azospirillum for cereals, millets and vegetables (free-living N fixers), PSB to unlock soil phosphorus, KMB for potassium, and Acetobacter for sugarcane. Many farmers combine an N-fixer with PSB.
Soil application or seed treatment?+
Both work; seed treatment (coating seed with the culture) is economical and targets the root zone, ideal for seed-sown crops; soil application (mixing the culture with FYM and broadcasting) suits transplanted crops, orchards and where seed treatment isn't practical. The tool gives the dose for each method.
How much nitrogen can a biofertilizer save?+
N-fixing biofertilizers can save roughly 25–30 kg N/ha for free-living fixers (Azotobacter/Azospirillum) and 50+ kg N/ha for Rhizobium on legumes — a meaningful cut in urea. PSB and KMB don't fix N but improve P and K availability. The tool estimates the N saved for your area.
How do I apply biofertilizer with FYM?+
Mix the recommended culture thoroughly into 25–50 kg of moist, well-rotted FYM or compost per acre, keep it in the shade for a few hours, then broadcast and incorporate into moist soil — ideally in the evening. The FYM acts as a carrier that protects and spreads the microbes.
Can I mix biofertilizer with chemical fertiliser or pesticide?+
Not at the same time — direct contact with concentrated chemical fertiliser, fungicides or strong agrochemicals can kill the microbes. Apply biofertilizer separately (a gap of a few days from chemical fungicide seed treatment), and never mix the culture into a fertiliser/pesticide tank.
Do biofertilizers replace fertiliser?+
No — they supplement it. They typically cut fertiliser needs by 15–25% and improve soil biology and long-term fertility, but crops still need a base of nutrients, especially at high yields. Use biofertilizers alongside soil-test-based fertiliser, FYM and good agronomy for the best result.
How should I store biofertilizer?+
Keep it cool and out of direct sunlight and heat (which kill the microbes), and use it before the expiry date — these are living products with a limited shelf life. Buy from a reliable source, check the manufacture/expiry date, and don't stockpile beyond one season.
Is biofertilizer worth it?+
Usually yes — it's low-cost, cuts fertiliser bills (especially nitrogen on legumes), and builds soil health over time. The savings in urea alone often exceed the biofertilizer's cost in the first season. Use the tool's N-saved and cost figures to weigh it for your crop and area.