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Phosphorus Deficiency in Onion: Symptoms, Causes & How to Fix It

A complete agronomist guide to identifying and correcting Phosphorus deficiency in Onion crops. Includes visual symptom guide, soil test interpretation, and fertilizer recommendations.

Why Onion Needs Phosphorus

Phosphorus is an essential nutrient for Onion growth and development. Phosphorus is essential for root development, energy transfer (ATP), and flowering.

In India, Phosphorus Deficiency is particularly common in Onion grown in Maharashtra, Karnataka, Gujarat due to specific soil conditions in these regions.

Visual Symptoms of Phosphorus Deficiency in Onion

🔍 What to look for in your Onion field:

⚠️purple or reddish discoloration of leaves
⚠️dark green foliage
⚠️delayed maturity
⚠️poor root development
📊 Did you know? Phosphorus is essential for root development, energy transfer (ATP), and flowering.

Soil Causes of Phosphorus Deficiency in Onion

Phosphorus Deficiency in Onion is commonly caused by: Cold soils, acidic soils, compacted soils

A soil test is the most reliable way to confirm Phosphorus deficiency. Use SoilPro's NPK Calculator to get fertilizer recommendations based on your soil test values.

How to Correct Phosphorus Deficiency in Onion

ProductApplication MethodDoseTiming
DAP 18-46-0 (50 kg/acre)Soil50 kg/acreVegetative stage
SSP 16% P (100 kg/acre)Soil100 kg/acreVegetative stage
TSP 46% P (25 kg/acre)Soil25 kg/acreVegetative stage
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Frequently Asked Questions

What are the symptoms of Phosphorus Deficiency in Onion?

purple or reddish discoloration of leaves, dark green foliage, delayed maturity, poor root development

How quickly can I fix Phosphorus Deficiency in Onion?

Foliar sprays show improvement in 7-10 days. Soil applications take 2-3 weeks. Severe deficiency may need 2-3 foliar sprays at weekly intervals.

Does Phosphorus Deficiency affect Onion yield?

Yes significantly. Phosphorus deficiency reduces Onion yield by 20-50% depending on severity. It also reduces fruit/grain quality.

Which soil test should I do for Onion?

Test for pH, EC, N, P, K, Zn, Fe, Mn, B, and organic carbon. SoilPro can interpret any soil test report and give crop-specific recommendations.

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