Castor Fertilizer Calculator
Work out the exact urea, DAP and MOP for castor from the recommended 80:40:20 kg/ha N-P₂O₅-K₂O dose, adjusted to your soil test and field size.
Irrigated: 40 kg N + full P, K basal, then 20 kg N at primary-spike emergence and 20 kg at secondary spikes. Castor keeps throwing spike orders — late small N doses keep them filling.
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 Castor Fertilizer Calculator to convert the official castor 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 Castor Fertilizer Calculator
Castor yields in successive spike orders over many months, so irrigated crops get nitrogen as a basal plus two spike-timed boosters rather than one early slug. This calculator starts from the published recommendation of 80:40:20 kg/ha N-P₂O₅-K₂O (irrigated) or 40:20:0 kg/ha N-P₂O₅-K₂O (rainfed), 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 Castor Fertilizer Calculator
- 1Enter your field area and pick the unit (hectare, acre or bigha).
- 2Choose the growing condition (irrigated / rainfed) 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 Castor Fertilizer Calculator?
- ✓Official package-of-practices dose for castor — 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 castor?+
Irrigated: 80 kg N, 40 kg P₂O₅ and 20 kg K₂O per hectare; Rainfed: 40 kg N, 20 kg P₂O₅ and 0 kg K₂O per hectare. Irrigated: 40 kg N + full P, K basal, then 20 kg N at primary-spike emergence and 20 kg at secondary spikes.
Why split castor nitrogen by spike order?+
Each spike order is a fresh yield event. A 20 kg N booster as primary and secondary spikes emerge keeps later orders productive — one early dose runs out before they form.
What is the rainfed castor dose in Gujarat-style tracts?+
About 40:20:0 kg/ha at sowing. On those sandy alkaline soils potash response is rare, but soil-test before skipping K permanently.
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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