The 17 nutrients a crop needs, and why the one in shortest supply limits the harvest

Nitrogen is part of every protein and of chlorophyll. It determines how much leaf the crop grows and how green the leaves are. The leaves make the sugars that fill the grain.

When it is short

Older leaves turn pale yellow first, from the tip back, because the plant moves nitrogen out of old leaves into new ones. Plants stay small and thin. Grain has less protein.

Works with, and against

The plant needs sulfur to turn nitrogen into protein. A crop short of sulfur cannot use all the nitrogen it is given, and the nitrogen it does not use is lost from the field. A crop also needs potassium to make good use of nitrogen: nitrogen drives leaf growth, and potassium moves sugar out of the leaf. Nitrogen without enough potassium gives soft, tall growth that falls over.

In Pakistan’s soils

Pakistan applies more nitrogen than any other nutrient, and a larger share of the nitrogen is lost than of any other nutrient. Its nitrogen use efficiency was 29.1% in 2023 (FAOSTAT): about 71 of every 100 kg of nitrogen added to its cropland were not taken out in the harvested crop. Sulfur coated urea (SCU) releases its nitrogen gradually, over days rather than all at once, so more of it reaches the roots than from uncoated urea.

VAN products that contain it

Vital UreaSulfur coated urea. N 32% · S 13%Cala-Mag VN 10% · Ca 6% · Mg 4% · B 1%VL-NPKLiquid NPK 8:8:6 (% w/v, weight per volume). N 8 · P₂O₅ 8 · K₂O 6

Inside the plant, phosphorus is used to move energy, and the plant needs it to grow roots. It affects how fast a seedling puts down roots, how many tillers wheat makes, and how well the crop sets and fills its grain.

When it is short

Seedlings grow slowly and are dark green, sometimes with a purple tint on the older leaves and stems. The crop makes fewer tillers, flowers late and forms small heads. Most of the damage is done in the first weeks and cannot be undone later.

Works with, and against

Phosphorus and zinc work against each other: a heavy dose of phosphate on a soil already low in zinc makes the zinc shortage worse. Inside the plant, phosphorus needs calcium. In the soil, calcium binds phosphate into forms the root cannot take up. This binding is the central phosphorus problem in Pakistan’s soils.

In Pakistan’s soils

In the Punjab soil survey (770,160 samples, tested in about 2016 to 2018), the median available phosphorus (measured as elemental phosphorus) was in the Critical or Weak band of VAN’s 5-band soil-test scale in 35 of the 36 districts. In the same survey, 69.1% of samples were above pH 8, and calcareous soil above pH 8 binds applied phosphate before the root reaches it. The Soil Atlas shows each district.

VAN products that contain it

Green Phosphate6:32:0 · humic-coated acidic. The 6:32 grade of the VAN NP Range, which has 3 gradesV-Phosphate11:44:0 + FeFusion PhosphateTriple superphosphate (TSP). P₂O₅ 46%V-Germinator ProLiquid. P₂O₅ 27% · N 4.5% · K₂O 2%, with Mg, S and Fe

Potassium controls the movement of water and sugar in the plant. It opens and closes the pores in the leaf, moves sugar from the leaf to the grain, tuber or fruit, and thickens the cell wall. It affects crop quality, grain weight and tolerance of stress: heat, drought and disease all do more damage to a crop that is short of potassium.

When it is short

Older leaves scorch along the edge and the tip while the centre of the leaf stays green. Stems are weak and the crop falls over (lodges). Grain is light, and fruit is small and stores badly.

Works with, and against

Potassium works with nitrogen: nitrogen drives leaf growth, and potassium moves sugar from the leaf to fill the grain. Too much potassium reduces the plant’s uptake of magnesium and calcium. Potassium, magnesium and calcium should therefore be planned together, not each applied on its own.

In Pakistan’s soils

In 2024-25, potash was 1% of the fertiliser nutrients applied in Pakistan (NFDC). VAN prints this figure on its Crop Force bag. VAN’s wheat balance page shows how much potash a wheat crop of 60 maunds per acre removes from the field when the straw (bhoosa) is also taken away.

VAN products that contain it

Vital PotashN 11% · K₂O 44%, boron-coated in 2 formsFusion Potash2:0:50 + S 1.5% · B 1% · Mg 1%. Made in 2 forms: granules for broadcasting and soluble powder for fertigation.V-Potash Plus10:0:40 + Mg · B · chelated FeSOPSulfate of potash. K₂O 50% · S 17.5%VL-Potash LiquidK₂O 30%. For foliar spray or fertigation

Calcium holds the cell walls together and is needed at every growing point. Once calcium is placed in a tissue it does not move again, so the crop needs a steady supply while it grows, especially where fruit and tubers are forming.

When it is short

The youngest tissue fails first: new leaves have burnt tips, tomatoes get blossom end rot, apples get bitter pit and potatoes get hollow heart. Old leaves look normal.

Works with, and against

Calcium and boron work together to build the cell wall, and boron is needed for calcium to move to the growing point. Too much potassium or magnesium in the soil reduces the calcium the root takes up.

In Pakistan’s soils

Pakistan’s soils hold a great deal of calcium in the form of lime. A crop can still be short of calcium, because the calcium in lime is not in a form the root can take up, and because a heavy dose of potash blocks its uptake.

VAN products that contain it

Cala-Mag VN 10% · Ca 6% · Mg 4% · B 1%

Magnesium sits at the centre of every chlorophyll molecule, so without it the leaf cannot stay green or make sugar. It also helps the plant move phosphorus.

When it is short

Older leaves go yellow between the veins while the veins stay green, giving a striped or marbled look. The yellowing starts on the lower leaves and moves up the plant.

Works with, and against

Too much potassium or too much calcium reduces the magnesium a crop takes up. When a fertiliser programme raises the potash dose without adding magnesium, the crop often shows a magnesium shortage in the same season.

VAN products that contain it

V-Mag EssentialMg 8.5% · B 1% powderCala-Mag VN 10% · Ca 6% · Mg 4% · B 1%V-Potash Plus10:0:40 + Mg · B · chelated FeFusion Potash2:0:50 + S 1.5% · B 1% · Mg 1%. Made in 2 forms: granules for broadcasting and soluble powder for fertigation.

Sulfur is part of 3 of the amino acids from which the plant builds protein, and of the oils in canola, mustard and sesame. The plant needs it to turn applied nitrogen into grain protein.

When it is short

Young leaves go pale yellow all over. Nitrogen shortage shows the opposite pattern and starts on the old leaves. Plants are thin and grow slowly, and oilseeds give less oil.

Works with, and against

Sulfur and nitrogen work as a pair: without enough sulfur, extra nitrogen is wasted. Elemental sulfur also makes the soil around each sulfur granule more acidic, and this can release phosphate and zinc that the soil holds near the granule.

In Pakistan’s soils

The Punjab soil testing programme did not test for sulfur, so the Soil Atlas cannot show it. VAN’s soil report does not test for sulfur either. No national figure for soil sulfur has been published.

VAN products that contain it

Green SulfurSulfur 70%, water-dispersible granules (WDG)Vital UreaSulfur coated urea. N 32% · S 13%SOPSulfate of potash. K₂O 50% · S 17.5%Fusion Potash2:0:50 + S 1.5% · B 1% · Mg 1%. Made in 2 forms: granules for broadcasting and soluble powder for fertigation.

Zinc is needed to make the growth hormone that lengthens the stem and the enzymes that build protein. It affects plant height, leaf size and, in rice and wheat, grain set.

When it is short

Young leaves come out small, narrow and yellow between the veins. The stem sections between the leaves (internodes) stay short, so the plant looks bunched. In maize, a white band appears down the young leaf. In rice nurseries, brown spots appear on the older leaves.

Works with, and against

Zinc and phosphorus work against each other, so a heavy phosphate dose makes a zinc shortage worse on a soil already low in zinc. At high pH, the soil binds zinc in the same way as it binds phosphate.

In Pakistan’s soils

The Soil Atlas shows the survey’s median zinc reading for each district; in several districts the median was in the Critical band. A grower can check the district there before deciding on a zinc dose.

VAN products that contain it

V-TransformZinc 21% granularV-Zinc 10%Zinc 10% w/v (weight per volume), as zinc sulfateVL-MicromixZn 5 · Fe 2 · Mn 2 · Cu 1 (% w/v, weight per volume)

Boron builds the cell wall together with calcium and carries sugar to the flower. It affects pollination, seed set and fruit set. When a cotton boll, a sunflower head or a rice panicle sets badly, boron shortage is often the cause.

When it is short

Growing points die, stems go hollow or cracked, flowers drop without setting, and fruit is misshapen. Cauliflower gets a hollow brown stem, and sugar beet gets a rotten heart.

Works with, and against

Boron and calcium work together at the growing point. The difference between enough boron and too much boron is small, which is why VAN coats boron onto its potash granules rather than relying only on a separate loose dose.

In Pakistan’s soils

In the Punjab soil survey (tested in about 2016 to 2018), 51.7% of samples were below Punjab’s working threshold for boron of 0.5 ppm (parts per million). The Soil Atlas shows each district’s median and its band.

VAN products that contain it

VL-BoronBoron 5% w/v (weight per volume), liquidVital PotashN 11% · K₂O 44%, boron-coated in 2 formsFusion Potash2:0:50 + S 1.5% · B 1% · Mg 1%. Made in 2 forms: granules for broadcasting and soluble powder for fertigation.V-Mag EssentialMg 8.5% · B 1% powderCala-Mag VN 10% · Ca 6% · Mg 4% · B 1%

Iron is needed to make chlorophyll and for the enzymes that carry electrons in the leaf. A leaf without iron cannot turn light into sugar.

When it is short

The youngest leaves go yellow between the veins while the veins stay sharply green, and then whole leaves turn white. Old leaves stay green, which distinguishes iron shortage from magnesium shortage.

Works with, and against

Iron and manganese compete for uptake, and at high pH the soil binds both. In Pakistan, iron shortage is usually caused by bicarbonate in irrigation water and lime in the soil, so a soil can hold plenty of iron that the root cannot take up.

In Pakistan’s soils

Iron is tested on VAN’s soil report and shown on the Soil Atlas. In 4 districts, the survey’s iron figures cannot be compared with those of the other 32 districts; the Soil Atlas notes that they suggest a different laboratory method.

VAN products that contain it

VL-MicromixZn 5 · Fe 2 · Mn 2 · Cu 1 (% w/v, weight per volume)V-Potash Plus10:0:40 + Mg · B · chelated FeV-Phosphate11:44:0 + FeV-Germinator ProLiquid. P₂O₅ 27% · N 4.5% · K₂O 2%, with Mg, S and Fe

Manganese splits water inside the leaf so that photosynthesis can run, and it helps the plant use nitrogen. It also strengthens the plant’s resistance to fungal disease.

When it is short

Young and middle leaves go yellow between the veins and show grey or brown speckles. In oats and wheat the condition is called grey speck.

Works with, and against

High pH and dry, well-aerated soil both make manganese less available. Too much iron or a heavy dose of lime makes the shortage worse.

In Pakistan’s soils

Manganese is tested on VAN’s soil report and shown on the Soil Atlas.

VAN products that contain it

VL-MicromixZn 5 · Fe 2 · Mn 2 · Cu 1 (% w/v, weight per volume)

Copper is needed by the enzymes that build lignin, the woody part of the stem, and for pollen to form. Cereals short of copper produce empty heads.

When it is short

Young leaves twist and wilt at the tip, heads emerge empty or half filled, and stems are weak. Copper shortage is rare in Pakistan.

Works with, and against

Organic matter holds copper tightly, so peaty and heavily manured soils can be short of copper while mineral soils are not.

In Pakistan’s soils

The median copper reading was in the Healthy band in all 32 Punjab districts where the survey figure is comparable. The Soil Atlas marks the other 4 districts as not comparable.

VAN products that contain it

VL-MicromixZn 5 · Fe 2 · Mn 2 · Cu 1 (% w/v, weight per volume)