Nitrogen deficiency is the most common nutrient problem in agriculture because nitrogen is the most mobile macronutrient in the soil — it leaches with heavy rain and is drawn out fastest by fast-growing crops. Unlike a pathogen, it is entirely reversible with the right fertilization, often within days of a foliar application.
Symptoms
- Uniform pale-green to yellow older leaves
- Stunted growth and thin stems
- Reduced tillering in cereals
Causes
- Leached soils after heavy rain or over-irrigation
- Low soil organic matter
- Cold soils that slow nitrogen mineralization
Treatment
- Side-dress with urea (46-0-0) or ammonium sulfate at label rate
- Foliar spray of 1–2% urea for a rapid response
- Incorporate composted manure
Prevention
- Test soil annually and follow an NPK plan
- Rotate with legumes to fix nitrogen
- Use cover crops to build organic matter
Which drug to use on Nitrogen Deficiency
Registered products, active ingredients, mixing rates, spray intervals and pre-harvest intervals for controlling nitrogen deficiency. Rotate between different FRAC/IRAC groups to avoid resistance.
Urea 46-0-0
Active ingredient: Urea nitrogen 46%
- Dose
- 100–150 kg/ha split, or 5 g per litre as a 2% foliar spray
- Interval
- Split into 2–3 side-dressings across the growth cycle
- Pre-harvest interval
- Not applicable
Incorporate into moist soil within a day — surface urea can lose 30% of its nitrogen to volatilisation.
NPK 15-15-15 compound
Active ingredient: Balanced N-P-K
- Dose
- 200–300 kg/ha at planting
- Interval
- Basal dose at planting or transplanting
- Pre-harvest interval
- Not applicable
The correct starting point when no soil test exists; follow up with nitrogen-only top-dressing.
Calcium ammonium nitrate (CAN 27%)
Active ingredient: Ammonium nitrate + calcium
- Dose
- 150–200 kg/ha top-dressed
- Interval
- At 3–4 weeks and again at 7–8 weeks after emergence
- Pre-harvest interval
- Not applicable
Preferred over urea on acidic soils because it supplies calcium and does not further acidify.
Well-rotted farmyard manure / compost
Active ingredient: Organic nitrogen
- Dose
- 10–20 t/ha incorporated before planting
- Interval
- Once per season
- Pre-harvest interval
- Not applicable
Slow-release nitrogen plus the organic matter that keeps mineral fertiliser working in the following seasons.
Doses shown are typical registered field rates. Always read the product label, confirm the product is registered for your crop and country, respect the pre-harvest interval (PHI), and wear the protective equipment the label specifies. PlantWatch AI provides agronomic guidance, not a legal spray recommendation.
Frequently asked questions
How fast does a plant recover from nitrogen deficiency?
A foliar urea spray can show visible greening within 3–5 days, while a soil side-dress typically takes 1–2 weeks to fully correct growth and color.
Why do older leaves yellow first with nitrogen deficiency?
Nitrogen is mobile within the plant, so it is pulled from older leaves and relocated to support new growth, causing the oldest leaves to yellow first.
NPK Fertilization Plan
Balanced macronutrient program based on soil test results.
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