Onion is a crop with significant nutritional requirements and can provide good returns to farmers when properly managed. To produce onions with good size, quality, and storage potential, farmers need to pay attention to soil preparation, quality seed, irrigation, weed management, pest and disease control, and proper fertilizer application.

For a farmer cultivating one acre of onions, fertilizers should not be applied simply by routine. Fertilizer requirements depend on soil condition, onion variety, irrigation system, and the desired production level.

STEP 1: TEST THE SOIL BEFORE PLANTING

Timing: Before preparing the field.

Before purchasing fertilizer, farmers are advised to conduct a soil test.

A soil test can help determine:

• Soil pH.
• Nitrogen (N) levels.
• Phosphorus (P).
• Potassium (K).
• Other nutrients, depending on the test.

Why is soil testing important?

Because fields are different. A field with sufficient Potassium will not require the same fertilizer program as a field with a Potassium deficiency.

Do not start applying large amounts of fertilizer without understanding the needs of your field.

STEP 2: LAND PREPARATION

Timing: Before planting or transplanting seedlings.

Manure or Compost

Apply well-decomposed manure or compost during land preparation.

It can help to:

• Increase organic matter in the soil.
• Improve soil structure.
• Create a favorable environment for root development.
• Improve the soil's ability to retain moisture.

Basal Fertilizer

Depending on soil-test results, a fertilizer containing Phosphorus (P) may be applied during land preparation or planting.

Fertilizers such as DAP or MAP may form part of the program where Phosphorus is required.

Important: Do not use DAP or MAP routinely without considering the actual needs of the soil.

STEP 3: PLANTING OR TRANSPLANTING SEEDLINGS

Timing: On the planting or transplanting day.

At this stage, the main objective is to ensure that the plants establish well and the roots have a favorable environment for growth.

Consider the following:

• Avoid severe transplanting shock.
• Ensure adequate soil moisture.
• Do not allow concentrated fertilizer to come into direct contact with young roots.
• Use appropriate plant spacing according to the onion variety and production system.

Important nutrients

• Phosphorus for root development.
• Nitrogen for early growth at an appropriate rate.
• Other nutrients according to soil requirements.

STEP 4: WEEK 1–2 — EARLY ESTABLISHMENT

During the first weeks, the plants begin developing their root systems and producing new leaves.

Fertilizers that may form part of the program include:

• NPK.
• CAN.
• Urea, where additional Nitrogen is required.

Objective

✓ Strengthen root development
✓ Support leaf growth
✓ Build healthy plants
✓ Prepare the crop for the next growth stages

Avoid excessive Nitrogen, because it can encourage excessive leaf growth without maintaining the nutrient balance needed for bulb development.

STEP 5: WEEK 3–5 — LEAF DEVELOPMENT

During this period, onions develop more leaves and build the foundation for bulb formation.

Focus on:

• Nitrogen at the required level.
• Phosphorus according to soil conditions.
• Potassium at an appropriate balance.
• Adequate irrigation.

Fertilizers that may be used include:

• NPK.
• CAN.
• Urea where additional Nitrogen is required.

For drip irrigation systems, some fertilizers suitable for fertigation may be applied through the irrigation system according to an appropriate program.

Do not apply large amounts of Urea or CAN without a proper plan.

STEP 6: WEEK 5–7 — BULB INITIATION

This is an important stage because the plant begins directing more of its growth toward bulb formation.

Nutritional focus

• Potassium (K).
• Phosphorus according to requirements.
• Nitrogen at an appropriate level.
• Micronutrients where required.

Objective

Support the development of strong and well-formed onion bulbs.

At this stage, farmers should be particularly careful about excessive Nitrogen application.

STEP 7: WEEK 7–10 — BULB DEVELOPMENT

During this period, the bulbs begin increasing in size.

Main focus

Potassium + balanced nutrition + proper irrigation

Potassium is an important part of an onion nutrition program during bulb development.

Consider the following:

✓ Maintain appropriate irrigation
✓ Provide adequate Potassium according to crop requirements
✓ Avoid excessive Nitrogen
✓ Monitor pests and diseases
✓ Control weeds on time

STEP 8: WEEK 10–12 AND BEYOND — BULB MATURITY

As the onions approach maturity, farmers should focus more on bulb quality and preparing the crop for harvesting.

Focus on:

• Balanced nutrition according to crop condition.
• Potassium where required.
• Reducing or stopping certain Nitrogen applications according to the crop stage and professional advice.
• Proper irrigation management as the crop approaches maturity.

Do not continue adding Nitrogen routinely when the crop is approaching harvest.

STEP 9: HARVESTING

Onions should be harvested when they reach the appropriate maturity stage.

Signs of maturity may include:

• Leaves beginning to fall over.
• The neck of the plant becoming softer.
• Bulbs reaching the expected size for the particular onion variety.

After harvesting, onions should be properly cured before storage.

Why is curing important?

Curing helps reduce excess moisture and prepares the onions for storage.

SIMPLE FERTILIZER SCHEDULE FOR ONE ACRE OF ONIONS

IMPORTANT FERTILIZERS IN ONION PRODUCTION

DAP/MAP

Provides Phosphorus along with other nutrients depending on the fertilizer formulation.

NPK

Provides Nitrogen, Phosphorus, and Potassium in the ratio contained in the particular formulation.

CAN

Provides Nitrogen together with Calcium and may be used as part of the crop nutrition program where required.

UREA

Contains approximately 46% Nitrogen. It is a concentrated Nitrogen fertilizer and should be used carefully according to crop requirements.

POTASSIUM FERTILIZERS

They are important components of onion nutrition, particularly during bulb development, depending on soil conditions.

MAGNESIUM AND MICRONUTRIENTS

Nutrients such as Magnesium, Sulfur, Boron, Zinc, and others may be required depending on soil conditions and crop needs.

FERTILIZER MISTAKES TO AVOID

❌ Applying fertilizer without testing the soil.
❌ Applying excessive Urea or CAN routinely.
❌ Placing fertilizer directly against young roots.
❌ Ignoring Potassium during bulb development.
❌ Applying too much fertilizer at one time.
❌ Neglecting proper irrigation.
❌ Waiting until the crop shows severe nutrient deficiency symptoms before taking action.

CHETU AGROSOLUTION — FERTILIZERS AND FARMING ADVICE

Are you growing one acre or more of onions and need the right fertilizers for each stage of crop development?

Visit CHETU AGROSOLUTION or contact us to get the fertilizers and agricultural inputs you need, together with professional advice on your crop nutrition program.

We can help farmers access:

✓ Basal and top-dressing fertilizers
✓ NPK
✓ DAP/MAP
✓ CAN
✓ Urea
✓ Potassium fertilizers
✓ Magnesium and micronutrients
✓ Other agricultural inputs
✓ Advice on proper fertilizer application
✓ Guidance on onion crop nutrition at different growth stages

Do not wait until your onions begin showing serious nutrient deficiency symptoms. Plan your crop nutrition early.

CHETU AGROSOLUTION

For fertilizers, agricultural inputs, and professional farming advice, visit CHETU AGROSOLUTION or contact us today.

Successful farming starts with quality seed, healthy soil, proper nutrition, good irrigation, and the right advice.