Nitrogen deficiency
A uniformly pale, slow-growing crop that yellows from the oldest leaves up — the single most yield-limiting deficiency in Indian farming.
- Nutrient type
- Primary (macro)
- Mobility in plant
- Mobile
- Symptoms start on
- Old (lower) leaves
- Most at risk
- Sandy, low-organic soils
Overview
Nitrogen is the nutrient a crop needs in the largest amount and the one most often short. It builds chlorophyll and protein, so a shortage shows first as loss of green colour and then as visibly slower growth and thin, spindly tillers or branches.
The tell-tale is where the yellowing starts. Nitrogen is mobile inside the plant — when supply runs low the crop pulls it out of its old leaves to feed the new growth, so the bottom, oldest leaves pale and yellow first while the top stays greener. A deficiency caught at an early vegetative stage can still be fully corrected; caught at flowering, some yield is already lost.
How to spot it
- Whole plant is pale green to yellow, and the colour is even across the leaf — not a pattern between the veins.
- Yellowing begins on the oldest, lowest leaves and moves up the plant as it worsens; the newest leaves stay greenest.
- Growth is stunted and spindly — fewer tillers in cereals, fewer branches in cotton or pulses, small leaves.
- In severe cases the oldest leaves dry from the tip and fall early; the whole field looks thin and yellow-green from a distance.
Why it happens
- Sandy and light soils and soils low in organic matter simply hold little nitrogen.
- Heavy rain or over-irrigation leaches nitrate below the root zone, and waterlogging drives gaseous loss (denitrification).
- Top dressing applied late, or broadcast on a dry field and never watered in, so the crop never reaches it at the stage it needed it.
- A heavy cereal residue (paddy straw) ploughed in just before sowing ties up soil nitrogen as it rots.
Confirm before you spend
- A pale, even yellowing from the bottom up is close to diagnostic — but sulphur deficiency looks similar, except it starts on the new leaves, not the old ones.
- A soil test under the Soil Health Card scheme gives your field’s nitrogen status; a leaf-colour chart (LCC) is a cheap in-field way to time top dressing in rice and wheat.
How to correct it
- For a standing crop already showing symptoms, top dress urea (46% N) and irrigate immediately so it reaches the roots — never leave it on a dry surface.
- For a fast knock-down of visible yellowing, spray 2% urea (2 kg urea in 100 litres of water per acre); repeat after 10–15 days if needed. Foliar feeding is a rescue, not a substitute for soil nitrogen.
- Split the total nitrogen dose — part at sowing, the rest as one or two top dressings at the crop’s peak-demand stages (tillering and jointing in wheat, tillering and panicle in rice) rather than all at once.
- The exact dose depends on the crop and soil test; follow the crop’s package of practices for the per-hectare figure rather than a blanket rate.
Prevent it coming back
- Build soil organic matter with FYM or compost and grow a legume or green-manure crop (dhaincha, sunhemp) in rotation — it fixes nitrogen for the next crop.
- Time and split nitrogen to the crop’s demand curve, and use a leaf-colour chart or the "green-seeker" approach to apply only what the crop is actually short of.
- Avoid over-irrigation and improve drainage on heavy soils to cut leaching and denitrification losses.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
How do I tell nitrogen deficiency from sulphur deficiency? They both yellow the crop.
By which leaves go first. Nitrogen is mobile, so it yellows the OLD, lower leaves first. Sulphur is immobile, so it yellows the NEW, upper leaves first. If the top of the plant is the palest, suspect sulphur, not nitrogen — common in mustard, groundnut and pulses.
Can I just spray urea to fix it?
A 2% urea spray gives a quick green-up and is a good rescue for a visibly hungry crop, but foliar feeding only supplies a small fraction of the crop’s total need. Use it to buy time, then correct the underlying shortage with soil top dressing and irrigation.
Why did my crop go yellow right after heavy rain?
Heavy rain leaches nitrate nitrogen below the root zone, and waterlogging drives gaseous loss. Both strip available nitrogen fast. A top dressing after the field drains, watered in, usually recovers it — and splitting nitrogen into more doses reduces the loss next time.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.