Onion Fertilizer Calculator
Work out the exact urea, DAP and MOP for onion from the recommended 110:40:60 kg/ha N-P₂O₅-K₂O dose, adjusted to your soil test and field size.
Half N + full P, K + sulphur as basal; remaining N in two splits at 30 and 45 days after transplanting. Stop N by bulb initiation — late N produces thick necks that store badly.
Indicative planning figures based on published research averages. Local soil tests, varieties and weather change actual requirements — confirm with your agronomist or extension officer.
Farmers and agronomists use the free Onion Fertilizer Calculator to convert the official onion recommendation into exact urea, DAP and MOP quantities for their own field in seconds — no agronomy tables, no spreadsheet, and it works offline in the field.
About Onion Fertilizer Calculator
Onion is a sulphur-loving crop: 30–45 kg S/ha sharpens pungency and improves storage, so the calculator carries a separate sulphur line in the plan. This calculator starts from the published recommendation of 110:40:60 kg/ha N-P₂O₅-K₂O (rabi (main)) or 100:50:50 kg/ha N-P₂O₅-K₂O (kharif), adjusts it ±25% for your soil-test N, P and K ratings, scales it to your field area in hectares, acres or bigha, and converts the nutrients into real products — urea (46% N), DAP (18-46-0) and MOP (0-0-60) — including the number of bags to buy.
How to use Onion Fertilizer Calculator
- 1Enter your field area and pick the unit (hectare, acre or bigha).
- 2Choose the growing condition (rabi (main) / kharif) and your soil-test ratings for N, P and K — leave Medium if you have no recent soil test.
- 3Read off the urea, DAP and MOP quantities and bag counts, then follow the split-application note for timing.
Why use Onion Fertilizer Calculator?
- ✓Official package-of-practices dose for onion — not a generic NPK guess
- ✓Soil-test Low/Medium/High ratings adjust the dose ±25% automatically
- ✓Converts nutrients to urea, DAP and MOP bags, with the DAP nitrogen credit handled correctly
- ✓Works in hectares, acres and bigha — and runs fully in your browser, even offline in the field
Frequently asked questions
What is the recommended fertilizer dose for onion?+
Rabi (main): 110 kg N, 40 kg P₂O₅ and 60 kg K₂O per hectare; Kharif: 100 kg N, 50 kg P₂O₅ and 50 kg K₂O per hectare. Half N + full P, K + sulphur as basal; remaining N in two splits at 30 and 45 days after transplanting.
Why does onion need sulphur fertilizer?+
Sulphur builds the flavour compounds (allyl sulphides) that give onion pungency and also improves bulb firmness and shelf life. Packages recommend 30–45 kg S/ha, commonly given as ~200 kg gypsum.
What happens if I give onion too much nitrogen late?+
Late nitrogen keeps the tops growing, producing thick-necked bulbs that cure poorly and rot in storage. Finish all N by 45 days after transplanting, before bulbing starts.
How does the calculator convert NPK into urea, DAP and MOP?+
DAP (46% P₂O₅) is sized to cover the phosphorus need; the nitrogen it also carries (18% N) is credited against the N requirement, and urea (46% N) supplies the balance. MOP (60% K₂O) covers potassium. Bag counts use 45 kg urea and 50 kg DAP/MOP bags.
Is this tool free, and does my data leave the device?+
It is completely free with no sign-up, and all calculation happens in your browser — nothing you enter is uploaded, so it also works offline in the field.
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