The quickest way to identify a nutrient deficiency is to look at where the symptoms appear first. Shortages of mobile nutrients, such as nitrogen, phosphorus, potassium and magnesium, show up on older, lower leaves, because the plant moves these nutrients to new growth. Shortages of immobile nutrients, such as sulphur, zinc, iron, boron and calcium, show up first on young leaves and growing points.
This field guide describes the main symptoms, the conditions that cause them and the fertilizers that correct them. Symptoms can look alike, so confirm with a soil test or leaf analysis before spending money.
Deficiency symptoms at a glance
| Nutrient | Where it shows first | Typical symptoms | Common causes | Usual correction |
|---|---|---|---|---|
| Nitrogen (N) | Older leaves | Whole leaf pale green to yellow; slow growth; in maize a yellow V from the tip | Low organic matter, leaching, waterlogging, too little fertilizer | Urea, ammonium sulphate, CAN |
| Phosphorus (P) | Older leaves | Dark green or purple tints; stunted plants; poor roots; late maturity | Acid or alkaline soils, cold wet soil, low soil P | DAP, MAP, TSP |
| Potassium (K) | Older leaves | Yellow then brown scorching along leaf edges; weak stems; small fruit | Sandy soils, heavy cropping, high calcium or magnesium | MOP, SOP |
| Magnesium (Mg) | Older leaves | Yellowing between veins while veins stay green; sometimes reddish tints | Acid sandy soils, heavy potash use | Kieserite, dolomitic lime, Mg-containing NPK |
| Sulphur (S) | Younger leaves | Whole young leaves pale yellow; resembles nitrogen deficiency but on new growth | Light soils, low organic matter, cleaner air | Ammonium sulphate, SOP, SSP |
| Zinc (Zn) | Younger leaves | Small leaves, short internodes, pale bands (maize) or bronzing (rice) | Alkaline, calcareous or flooded soils; high P | Zinc sulphate, zinc-enriched NPK |
| Iron (Fe) | Younger leaves | Yellowing between veins on new leaves, which can turn almost white | High pH and calcareous soils | Chelated iron, soil acidification |
| Boron (B) | Growing points | Dead growing tips, brittle leaves, poor flowering and seed set, hollow stems | Sandy soils, high pH, dry conditions | Borax, boric acid, soluble borates |
| Calcium (Ca) | Young tissue and fruit | Blossom end rot, tip burn, distorted new leaves | Irregular watering more often than low soil Ca | Calcium nitrate, gypsum, lime |
How to diagnose correctly
- Look at the pattern in the field. Deficiencies often follow soil types, old field boundaries, wet patches or sandy ridges. Pests and diseases tend to spread in other patterns.
- Check where on the plant symptoms start: old leaves, new leaves or growing points.
- Rule out look-alikes: drought, waterlogging, herbicide damage, root diseases, cold and too much fertilizer can all cause yellowing or scorch.
- Confirm with tests. A soil test shows what is available in the soil. Plant tissue or leaf analysis shows what the crop has actually taken up, and is the standard method in tree crops such as oil palm and citrus.
- Check soil pH. Many deficiencies are caused by pH, not by a lack of the nutrient in the soil.
Hidden hunger
A crop can lose yield to a nutrient shortage before any symptoms appear. This is called hidden hunger. By the time leaves change colour, some yield is usually already lost. Regular soil testing and, for high-value crops, leaf analysis catch shortages earlier than the eye can.
Correcting a deficiency
- Soil application builds up levels for the current and following crops.
- Foliar sprays correct micronutrient and some secondary nutrient shortages quickly during the season, though the effect is short-lived.
- Fertigation suits irrigated crops and allows small, frequent corrections.
- Fix the cause: lime acid soils, improve drainage, and add organic matter where it is low. Organic fertilizers such as manure pellets supply a broad range of nutrients.
For how each nutrient drives yield, see how fertilizer affects plant growth. For crop programmes, see our guides to cassava, tobacco and sugarcane.
Buying fertilizer in bulk
Agromer has traded agricultural commodities internationally since 1985 from Saint-Avertin, France. We supply urea, NPK, DAP, potash and organic fertilizers to importers, distributors and large growers. Send your product, quantity, packaging and destination and we confirm availability and terms.
Frequently asked questions
How do you identify a nutrient deficiency in plants?
Check whether symptoms start on old leaves (nitrogen, phosphorus, potassium, magnesium) or young leaves and growing points (sulphur, zinc, iron, boron, calcium), then confirm with a soil or leaf test.
What does nitrogen deficiency look like?
Pale green to yellow plants, with the oldest leaves yellowing first, and slow growth.
What is the difference between nitrogen and sulphur deficiency?
Both cause yellowing, but nitrogen deficiency starts on older leaves and sulphur deficiency starts on younger leaves.
Why are my plant leaves yellow between the veins?
On older leaves, usually magnesium deficiency. On young leaves, usually iron or manganese deficiency, often caused by high soil pH.
What is hidden hunger in crops?
A nutrient shortage that reduces yield before visible symptoms appear.
Can foliar fertilizer fix deficiencies?
Foliar sprays correct many micronutrient shortages quickly, but major nutrients like nitrogen, phosphorus and potassium are mainly supplied through the soil.