🧪 Onion Nutrient Requirements
Onion (Allium cepa) is grown primarily in Maharashtra, Madhya Pradesh, Karnataka, Gujarat, Rajasthan. The crop requires a balanced supply of macro and micronutrients throughout its growth cycle. Key nutritional priorities include:
- Nitrogen (N): Essential for vegetative growth, leaf area development and protein synthesis
- Phosphorus (P): Critical for root development, energy transfer and flowering
- Potassium (K): Most important for fruit quality, sugar accumulation, disease resistance and water use efficiency
- Calcium (Ca): Cell wall integrity, prevents physiological disorders
- Magnesium (Mg): Chlorophyll component, enzyme activation
- Boron (B): Pollen viability, fruit set, calcium uptake
- Zinc (Zn): Enzyme function, auxin synthesis, growth regulation
- Iron (Fe): Chlorophyll synthesis, respiratory enzymes
📅 Stage-wise Spray Schedule
| Growth Stage | Recommended Product | Dose | Purpose |
|---|---|---|---|
| Pre-planting / Soil | Zinc Sulphate 33% + FYM | 25 kg/acre soil | Correct soil zinc deficiency |
| Seedling / Nursery | NPK 19:19:19 + TE | 2–3 g/L foliar | Balanced nutrition for establishment |
| Vegetative Growth | NPK 30:10:10 or 20:10:10 | 3–4 g/L or fertigation | Promote leaf area and canopy |
| Pre-flowering | NPK 12:61:00 (MAP) + Boron 10% | 3 g/L + 1 ml/L | Induce flowering, improve fruit set |
| Flowering | Calcium Nitrate + Boron 10% | 3 g/L + 0.5 ml/L | Pollen viability, fruit set |
| Fruit Development | NPK 13:00:45 or 0:0:50 SOP | 3–4 g/L foliar | Size, colour, sugar accumulation |
| Pre-harvest | Potassium Sulphate + Calcium | 4 g/L + 2 g/L | Firm fruit, extend shelf life |
| Post-harvest | Zinc EDTA + Iron EDTA combo | 1 ml/L each | Replenish reserves for next season |
🔬 Nutrient Deficiency Identification
The following deficiencies are most commonly observed in Onion crops in India:
- Sulphur deficiency (reduces pungency)
- Purple blotch
- Thrips
- Bulb splitting
- Storage rot
| Nutrient | Visual Symptom | Corrective Product | Method |
|---|---|---|---|
| Zinc | Interveinal chlorosis, small leaves, shortened internodes | Zinc EDTA 12% or Zinc Sulphate 33% | Foliar 0.5% or soil |
| Iron | Young leaf yellowing, veins stay green | Iron EDDHA 6% (soil) or Iron EDTA 12% (foliar) | Soil drench or foliar |
| Boron | Poor fruit set, distorted growing tips | Boron Ethanolamine 10% or Borax 11% | Foliar 0.1–0.3% |
| Calcium | Tip burn, fruit cracking, BER | Calcium Nitrate 4-0-0-26Ca | Foliar or fertigation |
| Magnesium | Interveinal chlorosis on older leaves | Magnesium Sulphate 9.9% Mg | Foliar 1–2% |
🛒 Recommended Products for Onion
These products from Green Vision Technical Services are specifically recommended for Onion nutrition:
Click any product to view specifications, dosage and download COA/MSDS/TDS.
⚖️ Annual Fertilizer Dosage for Onion
| Nutrient | Per Acre per Season | Application Method | Timing |
|---|---|---|---|
| Nitrogen (N) | 50–120 kg/acre | Fertigation / Soil | Split — vegetative to fruiting |
| Phosphorus (P₂O₅) | 25–60 kg/acre | Basal + fertigation | Planting + pre-flowering |
| Potassium (K₂O) | 60–150 kg/acre | Fertigation / Foliar | From fruit set to harvest |
| Calcium (Ca) | 15–30 kg/acre | Foliar + fertigation | Flowering + fruit development |
| Magnesium (Mg) | 8–15 kg/acre | Foliar | Vegetative to fruiting |
| Boron (B) | 0.5–1 kg/acre | Foliar | Pre-flowering + flowering |
| Zinc (Zn) | 2–5 kg/acre | Foliar or soil | Vegetative + fruiting |
Note: Doses vary based on soil test, crop variety and irrigation method. Always do soil testing before applying nutrients.
❓ Frequently Asked Questions — Onion Nutrition
What is the best NPK ratio for Onion? +
For Onion, the NPK ratio varies by growth stage. Use high-nitrogen grades (30:10:10 or 20:10:10) during vegetative growth, switch to high-phosphorus (12:61:00 or 13:40:13) at pre-flowering, and use high-potassium grades (13:00:45 or 00:00:50) from fruit set to harvest. Always adjust based on soil test results.
How to correct zinc deficiency in Onion? +
For immediate correction, spray Zinc EDTA 12% at 1–2 ml/L foliar. For soil application, apply Zinc Sulphate 33% at 10–25 kg/acre. Zinc EDTA is more effective at higher soil pH (above 7.0) as EDTA chelate remains stable. Repeat foliar spray every 15 days until symptoms disappear.
When should boron be applied for Onion? +
Boron is most critical at pre-flowering and early flowering stages. Apply Boron Ethanolamine 10% at 1–2 ml/L, 15 days before expected flowering and repeat at flower initiation. Boron improves pollen germination, pollen tube growth and fruit set. Avoid boron during hot afternoons to prevent phytotoxicity.
What is the best time to spray fertilizers on Onion? +
Spray early morning (6–9 AM) or late evening (5–7 PM) when temperature is below 32°C. Avoid spraying during hot afternoons, rainy conditions or immediately before irrigation. Ensure leaves are dry before applying systemic pesticides after foliar nutrition spray.
Can I mix NPK fertilizers with pesticides in tank? +
Most water-soluble NPK and EDTA chelated micronutrients are compatible with common pesticides. Always do a jar test before large-scale mixing. Avoid mixing alkaline pesticides (copper-based, lime sulphur) with acidic micronutrient solutions. Do not mix more than 3 products without testing compatibility.