How to Apply Fertilizer to Onion for Optimal Yield in Nigeria. Onion farming is a profitable venture in Nigeria, but maximizing yield depends heavily on proper fertilizer application. As professional agricultural experts, we understand that getting the fertilizer type, timing, and method right is critical for producing market-quality onion bulbs. Below is a complete, data-backed guide on how to apply fertilizer to onions in Nigeria for the best results.

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Understanding Onion Nutrient Requirements

Onions are heavy feeders that require a steady supply of nutrients throughout their growth stages. The major nutrients include:

• Nitrogen (N): Promotes vegetative growth and bulb size
• Phosphorus (P): Encourages root development and early growth
• Potassium (K): Enhances bulb quality, size, and disease resistance
• Secondary Nutrients: Sulphur, magnesium, and calcium are essential for pungency and structure

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Soil Preparation and Baseline Fertilization

Before planting, perform a comprehensive soil test to determine nutrient status and pH level. Onions prefer slightly acidic to neutral soils with a pH of 6.0–7.0.

Step-by-Step Pre-Plant Fertilizer Application:

1. Plough and Harrow the Soil: Ensure a fine tilth for root penetration.
2. Incorporate Organic Matter: Mix in 4–6 tons/ha of well-rotted poultry manure or compost two weeks before transplanting.
3. Apply Basal NPK Fertilizer:
   • Recommended Rate: NPK 15-15-15 at 300–400kg/ha
   • Timing: Apply during final land preparation, mix into the soil to a depth of 10–15cm.

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Fertilizer Schedule for Onion Growth Stages

🌱 Stage 1: Transplant to Establishment (Week 1–3)

• Goal: Encourage root development and early leaf growth.
• Fertilizer:
  • Apply NPK 20-10-10 at 200kg/ha in split doses.
  • First dose: 10 days after transplanting (DAT)
  • Second dose: 20 DAT

🌿 Stage 2: Bulb Initiation (Week 4–6)

• Goal: Stimulate bulb formation and canopy development.
• Fertilizer:
  • Apply Urea (46% N) at 150kg/ha in split doses.
  • Combine with Sulphate of Potash (K₂SO₄) at 100kg/ha to boost potassium.
  • Apply via side dressing 10–15cm away from the base of the plant.

🧅 Stage 3: Bulb Enlargement (Week 7–10)

• Goal: Maximize bulb size and weight.
• Fertilizer:
  • Apply Calcium Ammonium Nitrate (CAN) at 150kg/ha
  • Include Magnesium Sulphate foliar spray every 10 days.

🛑 Stage 4: Maturity (Week 11–14)

• Goal: Halt vegetative growth and allow bulbs to mature.
• Fertilizer: Stop all nitrogen applications after 10 weeks to avoid soft bulbs and poor storage quality.

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Fertilizer Application Techniques

• Side Dressing: Place fertilizer in a furrow 5–10cm away from the plant base and cover with soil.
• Fertigation (if using drip irrigation): Dissolve soluble fertilizers and feed through irrigation lines every 7–10 days.
• Foliar Feeding: Apply micro-nutrients like boron, zinc, and magnesium using foliar sprays every 2–3 weeks.

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Sample Fertilizer Plan for 1 Hectare Onion Farm

Growth Stage	Fertilizer Type	Quantity (kg/ha)	Application Time
Pre-Planting	Poultry Manure	5000–6000	2 weeks before planting
Land Preparation	NPK 15-15-15	400	Final harrowing
2 Weeks After Transplant	NPK 20-10-10	100	Split dose
4 Weeks After Transplant	Urea + Potassium Sulphate	150 + 100	Side dressing
7 Weeks After Transplant	CAN + MgSO₄	150 + foliar	Bulb development

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Environmental and Agronomic Best Practices

• Irrigation Management: Onions require frequent, shallow irrigation, especially during fertilizer application to avoid salt accumulation.
• Weed Control: Fertilizer promotes weed growth; practice hand weeding or use selective herbicides.
• Pest Monitoring: Ensure onion thrips and downy mildew are controlled to avoid nutrient uptake disruption.

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Storage Quality and Nutrient Residue

Avoid late nitrogen application to prevent soft bulbs and reduce post-harvest losses. High potassium during bulb maturation enhances firmness and shelf-life.

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Common Mistakes Farmers Make

• Over-application of Nitrogen: Leads to thick necks and poor bulb storage.
• Ignoring Micronutrients: Results in stunted growth and low pungency.
• Late Fertilization: Reduces bulb quality and encourages disease.

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Onion Fertilizer Schedule Flowchart

graph TD
    A[Land Preparation] --> B[Basal Fertilizer (NPK 15-15-15)]
    B --> C[Transplanting]
    C --> D[Early Growth - NPK 20-10-10]
    D --> E[Bulb Initiation - Urea + K₂SO₄]
    E --> F[Bulb Enlargement - CAN + MgSO₄]
    F --> G[Cease Fertilization at Maturity]

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Conclusion

Proper fertilizer management is the backbone of successful onion farming in Nigeria. By tailoring nutrient application to each growth stage, using the right formulations, and applying them using the most effective techniques, farmers can dramatically boost yield, bulb quality, and profitability. Implementing this guide ensures your onions meet market standards and command premium prices.

For premium quality onion fertilizer kits tailored for Nigerian soils, visit Farmpays Onion Fertilizer Solutions.

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