Micronutrient Spray Calculator & Zinc, Iron, Boron Foliar Dose
Doses zinc
Mix a foliar micronutrient spray right — pick the nutrient and your spray volume for the amount to dissolve, the neutralising lime where needed, and the per-tank dose.
Enter your spray
Next: confirm the deficiency from the leaf symptoms first, spray in the cool early-morning or evening hours, and repeat after 10–15 days if symptoms persist.
0.5% = 5 g/L; add lime in equal measure with zinc/copper sulphate to prevent leaf scorch.
Micronutrient spray — key facts
- Zinc sulphate
- 0.5% (5 g/L) + lime
- Ferrous sulphate
- 0.5%
- Borax / boron
- 0.2%
- Copper sulphate
- 0.2% + lime
- Magnesium (Epsom)
- 1%
- 0.5%
- = 5 g per litre
- Spray when
- cool morning/evening
- Privacy
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Fix a deficiency fast, the right way
When leaves yellow or growth stalls from a micronutrient shortage — zinc, iron, boron, manganese — a foliar spray corrects it within days, because the nutrient enters the leaf directly and bypasses soil that locks it up (high pH locks zinc and iron especially). But the concentration matters: too weak and it fails, too strong (or unneutralised acidic salts) and it scorches the leaves.
This tool gives the exact nutrient to dissolve, the neutralising lime where needed (zinc and copper sulphate), the water and the per-tank amounts for your spray volume and concentration. Confirm the deficiency, spray in the cool of the day covering the foliage, and repeat at 10–15 day intervals while addressing the soil cause. Pair it with the Sulphur pH, Soil Texture and Spray & Tank Mix tools.
Right dose
Exact nutrient per litre — effective without scorching.
Add the lime
Auto lime for zinc/copper sulphate to prevent leaf burn.
Per-tank amounts
Know what to add to each knapsack or tank.
Fast correction
Foliar feeding bypasses soil lock-up to fix deficiency in days.
Frequently Asked Questions
How much zinc sulphate per litre of spray?+
A common foliar concentration is 0.5% — that is 5 g of zinc sulphate per litre of water (0.5 kg per 100 L), usually with about half as much lime to prevent leaf scorch. This tool gives the zinc sulphate, lime and water for your spray volume, plus the amount per tank.
What concentration should I use for each micronutrient?+
Typical foliar strengths: zinc sulphate 0.5%, ferrous (iron) sulphate 0.5%, manganese sulphate 0.5%, borax/boron 0.2%, copper sulphate 0.2%, magnesium sulphate (Epsom) 1%. The tool pre-fills each nutrient's usual concentration, which you can adjust to your local recommendation.
Why add lime with zinc or copper sulphate?+
Zinc and copper sulphate sprays are acidic and can scorch leaves; adding lime (about half the zinc sulphate weight, or an equal weight for copper as in Bordeaux mixture) neutralises them and makes the spray safe. The tool adds the right lime automatically for those nutrients.
When should I spray micronutrients?+
When deficiency symptoms appear or a soil/leaf test confirms a shortage, sprayed in the cool of morning or evening for good absorption and to avoid scorch. Foliar application corrects deficiencies fast — within days — because the nutrient enters the leaf directly, bypassing soil lock-up.
What does zinc deficiency look like?+
Zinc deficiency shows as interveinal yellowing of younger leaves and 'little leaf' (small, bunched leaves with short internodes) — common in rice, maize, citrus and many crops on high-pH or sandy soils. A 0.5% zinc sulphate + lime foliar spray corrects it quickly; the tool sizes it for your area.
How do I correct iron deficiency?+
Iron deficiency (chlorosis — yellowing of the youngest leaves with green veins) is common on alkaline soils. A 0.5% ferrous sulphate foliar spray (sometimes with a little citric acid to keep iron available) greens it up. Soil iron is often locked by high pH, so foliar feeding is the fast fix.
Can I mix several micronutrients together?+
Often yes, but check compatibility — some combinations precipitate or react. Many farmers use a ready multi-micronutrient foliar mix to avoid this. If mixing singly, dissolve each fully, add lime where needed, and do a small jar test first. This tool sizes one nutrient at a time.
How much spray volume do I need?+
Enough to wet the foliage — commonly 200–500 L/ha depending on crop size, less for young crops. Enter the total volume directly, or switch to 'by area' and give your spray volume per hectare and the area; the tool then sizes the nutrient and lime for the whole job.
Is foliar spray better than soil application?+
For micronutrients on problem soils, often yes — foliar feeding bypasses soil that locks up the nutrient (high pH locks zinc and iron), corrects deficiency within days, and uses far less material. Soil application suits larger or longer-term needs. Use foliar to fix a visible deficiency fast.
How often should I repeat the spray?+
Usually 2–3 sprays at 10–15 day intervals during active growth correct most deficiencies; severe cases may need more. Combine with addressing the soil cause (pH, organic matter) for a lasting fix. The tool sizes one spray; multiply for the number of rounds you plan.