Zinc Sulphate & Correct the Hidden Hunger
Feeds rice
Enter your target zinc rate, area and product form to get the zinc sulphate needed— to correct zinc deficiency and khaira in rice.
Correct zinc deficiency
Next: apply 23.8 kg/ha of zinc sulphate (total 19.3 kg), broadcast and mixed into soil before sowing, or 0.5% foliar spray on standing crops showing interveinal chlorosis.
Zinc sulphate comes as heptahydrate (~21% Zn) or monohydrate (~33% Zn); soil Zn lasts 2–3 seasons, so you needn't reapply every crop.
Zinc sulphate — key facts
- Heptahydrate
- ≈ 21% zinc
- Monohydrate
- ≈ 33% zinc
- Product needed
- zinc ÷ Zn fraction
- Deficiency signs
- interveinal yellowing, khaira
- Worst on
- alkaline, calcareous soils
- Residual
- lasts 2–3 years
- Apply
- basal soil dose or foliar spray
- Privacy
- Runs in your browser; nothing uploaded
Fix the most common micronutrient deficiency
Zinc deficiency is the most widespread micronutrient problem in farming — interveinal yellowing, stunted rosetted plants and the khaira disorder in rice all point to it, and it quietly costs yield even when nitrogen, phosphorus and potassium are fine. The fix is zinc sulphate, but the two common grades carry different amounts of zinc: heptahydrate about 21% and monohydrate about 33%, so the product you weigh out depends on which one you buy.
This tool gives the product per hectare, total product, area and zinc rate from your target zinc rate and the form you choose. Use it to buy the right amount, avoid over-applying a residual nutrient, and plan a basal dose or corrective foliar spray. Pair it with the Micronutrient Spray, Boron Application and Fertilizer NPK calculators for a complete nutrition plan.
Match the grade
21% or 33% Zn changes the product needed.
Beat khaira
Correct rice zinc deficiency in time.
Buy the right amount
Total zinc sulphate before market.
Avoid over-applying
Zinc is residual — dose right, not high.
Frequently Asked Questions
Why is zinc important for crops?+
Zinc is an essential micronutrient that crops need in small amounts for enzyme activity, growth-hormone production and grain formation. Zinc deficiency is one of the most widespread micronutrient problems worldwide, especially in rice, wheat and maize on alkaline, calcareous or intensively cropped soils, and it can cut yields sharply even when major nutrients are adequate.
What does zinc deficiency look like?+
Typical signs are interveinal yellowing of younger leaves, stunted plants with shortened internodes (a rosette look), and in rice the well-known khaira disorder — bronze or brown spots on leaves that appear a few weeks after transplanting. Catching these symptoms early and applying zinc sulphate corrects the deficiency before yield is lost.
Which zinc sulphate should I use?+
Two forms are common. Zinc sulphate heptahydrate contains about 21% zinc; zinc sulphate monohydrate contains about 33% zinc. Monohydrate is more concentrated, so you need less product for the same zinc rate. The calculator lets you choose the form so the product quantity matches the grade you actually buy.
How is the product quantity calculated?+
Zinc needed = target zinc rate × area. Product needed = zinc needed ÷ the zinc concentration of the form (about 0.21 for heptahydrate, 0.33 for monohydrate). So a target zinc rate over your field is converted into kilograms of the actual zinc sulphate product you will spread or spray.
How much zinc do crops usually need?+
Soil application rates are often in the range of a few to around 25 kg of zinc sulphate heptahydrate per hectare depending on the crop, soil test and severity of deficiency, applied once every two to three years as it has residual value. Foliar sprays use much lower concentrations. Always follow your soil test and local recommendation; enter that rate here.
Soil application or foliar spray?+
Soil application before or at sowing/transplanting builds soil zinc and has lasting residual benefit, ideal where deficiency is established. Foliar sprays of a dilute zinc sulphate solution give a fast correction when symptoms appear mid-season. Many farmers combine both — a basal soil dose plus a corrective spray if symptoms show.
Does this work for any area unit?+
Yes — enter the target zinc rate and the area in acres, hectares, bigha, guntha or m², pick the product form, and the tool returns the product per hectare, the total product, the area and the zinc rate. The chemistry is the same across crops; only the rate changes with crop and soil.
Can I apply too much zinc?+
Yes — zinc can become toxic at very high rates and can also induce other micronutrient imbalances, so more is not better. Stick to the soil-test recommendation and the residual nature of zinc: a correct dose lasts two to three years. Use this tool to apply the right amount rather than over-applying every season.
Are the figures precise?+
They are solid planning figures based on the form's zinc content and your target rate. Real needs depend on soil pH, organic matter, the crop and the actual grade purity of the product. Base the rate on a soil test where possible and adjust to local recommendations and your field's history.