Sulphur deficiency
A pale crop that yellows from the top down — the new leaves first — now one of the most widespread deficiencies in Indian oilseeds and pulses.
- Nutrient type
- Secondary
- Mobility in plant
- Immobile
- Symptoms start on
- New (upper) leaves
- Most at risk
- Oilseeds, pulses, light soils
Overview
Sulphur is a building block of protein and of the oils in oilseed crops, so a shortage hits mustard, groundnut, soybean and sunflower hardest — both in yield and in oil content. It has spread quietly across India as farmers switched from sulphur-carrying fertilisers (single super phosphate, ammonium sulphate) to high-analysis ones (DAP, urea) that carry none.
The symptom looks like nitrogen deficiency — a pale, yellow-green crop — with one crucial difference: sulphur is immobile in the plant, so the crop cannot move it from old leaves to new. The youngest, uppermost leaves therefore yellow first and stay palest, the reverse of nitrogen. Getting this direction right saves buying the wrong fertiliser.
How to spot it
- The youngest, top leaves turn pale green to yellow first and stay the palest — the whole plant can look light-green in a bad case.
- Unlike nitrogen, the older lower leaves stay greener than the new growth; the yellowing is uniform across the young leaf, not between the veins.
- Plants are stunted with thin stems; in mustard the leaves cup and flowering is delayed, and pods set poorly.
- In pulses, nodulation and the deep green of a healthy legume are both missing.
Why it happens
- A shift from sulphur-carrying fertilisers (SSP, ammonium sulphate) to high-analysis DAP and urea, which supply no sulphur.
- Light, sandy soils and soils low in organic matter hold little sulphate, and it leaches easily like nitrate.
- High-yield oilseed and pulse crops remove a lot of sulphur, so the soil runs down fast if none is replaced.
- Little or no FYM/compost, which is a traditional source of sulphur.
Confirm before you spend
- The single most useful check is direction: sulphur yellows the NEW top leaves, nitrogen yellows the OLD bottom ones. If the top of the plant is palest, it is sulphur.
- A soil test that includes available sulphur, and knowing your crop — an oilseed or pulse on a light soil with only DAP/urea applied is the classic setting for it.
How to correct it
- Apply gypsum (calcium sulphate) or bentonite-sulphur to the soil at sowing per the crop recommendation — oilseeds and pulses have a specific sulphur dose in their package of practices.
- Single super phosphate is an easy way to supply sulphur and phosphorus together; ammonium sulphate supplies sulphur with nitrogen.
- For a standing crop already yellowing, spray 0.5% elemental sulphur or a soluble sulphate; recovery is slower than for nitrogen because sulphur cannot be moved within the plant.
- On groundnut, gypsum applied at pegging also feeds the pods with calcium — a double benefit.
Prevent it coming back
- Include a sulphur source in the fertiliser plan for every oilseed and pulse crop — do not rely on DAP and urea alone.
- Add FYM or compost and return residues to rebuild the soil’s sulphur-holding organic matter.
- On light soils, apply sulphur close to the crop’s need rather than long in advance, since sulphate leaches.
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 is this different from nitrogen deficiency? Both make the crop yellow.
The direction is opposite. Sulphur is immobile, so it yellows the NEW, upper leaves first and they stay palest. Nitrogen is mobile, so it yellows the OLD, lower leaves first. Check the top of the plant — if that is the palest part, it is sulphur, not nitrogen.
Why has sulphur deficiency become so common?
Because fertiliser habits changed. Older fertilisers like single super phosphate and ammonium sulphate carried sulphur as a bonus. As farmers moved to DAP and urea — which have none — sulphur stopped being replaced, and oilseed and pulse crops mined the soil down. Adding gypsum or SSP fixes it.
Which crops suffer most?
Oilseeds — mustard, groundnut, soybean, sunflower — because sulphur builds the oil itself, so a shortage cuts both yield and oil percentage. Pulses are next, then onion and garlic, which need sulphur for their pungency. These are the crops to plan a sulphur dose for.
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.