Choosing the Right Zinc Grade by Crop: Basal against Foliar Application
Published on: 2026-08-18 | Author: Neeraj Kedia, Managing Director | Read time: 6 min read
Applying zinc to a crop is not only about how much you use, but also about how and when you apply it. The two main routes are a basal soil dose worked in before sowing, and a foliar spray on the standing crop. Each suits a different grade of zinc sulphate and a different situation. This guide helps Indian growers choose the right zinc grade by crop, and decide between basal and foliar application.
Basal and Foliar: Two Ways to Apply Zinc
A basal application means mixing zinc sulphate into the soil before or at sowing, so the crop has zinc available from the start of the season. A foliar application means spraying a dilute zinc sulphate solution onto the leaves of a growing crop, which corrects a visible deficiency quickly. Basal application builds soil zinc and carries over across seasons, while foliar spray is a fast rescue when symptoms appear.
Monohydrate for Basal Soil Application
For a basal dose, Zinc Sulphate Monohydrate is preferred because its 33% or 35.5% zinc content delivers more zinc per kilogram, so you apply less material for the same result. A typical soil application is around 20 to 25 kg of monohydrate per hectare, mixed into the soil before sowing. The granular form spreads evenly and blends well with other basal fertilisers. Because soil applied zinc carries over, a basal programme reduces how often you need to reapply.
Heptahydrate for Foliar Spray
For a foliar spray on a standing crop, Zinc Sulphate Heptahydrate at 21% or 22% zinc dissolves quickly and sprays easily, which makes it well suited to a 0.5% foliar solution. Foliar application corrects a visible deficiency within about 7 to 10 days, so it is the right tool when a crop already shows symptoms such as pale striping between the veins or the brown spotting known as khaira in rice.
Zinc Grade by Crop
The table below is a general guide. Always confirm the exact rate against your soil test result and local agronomy advice before large scale application.
| Crop | Preferred method | Suggested grade |
|---|---|---|
| Rice (paddy) | Basal soil dose, with foliar rescue if khaira appears | Monohydrate 33% for soil, heptahydrate 21% for spray |
| Wheat | Basal soil application before sowing | Monohydrate 33% or 35.5% |
| Maize | Basal at sowing, foliar at early growth if needed | Monohydrate for soil, heptahydrate for foliar |
| Cotton and sugarcane | Basal soil dose | Monohydrate 33% or 35.5% |
| Fruits and vegetables | Foliar spray during active growth | Heptahydrate 21% or 22% |
| Pulses | Basal soil dose | Monohydrate 33% |
How to Decide Between Basal and Foliar
- Planning ahead before sowing: use a basal soil dose of monohydrate to build zinc for the whole season.
- A crop already showing deficiency: use a foliar spray of heptahydrate for a fast correction.
- High pH, sandy or calcareous soils where zinc locks up: rely on a basal dose and monitor with soil tests.
- Short duration or high value crops: a foliar spray can top up zinc at the critical growth stage.
A Combined Programme Often Works Best
In practice, many growers apply monohydrate as a basal dose worked into the soil before sowing, then keep heptahydrate ready for a foliar spray if the crop shows deficiency later. This combination builds soil zinc for the long term and gives a quick correction when it is needed. If you are unsure which grade and method suit your crop, our sales team can recommend the right zinc sulphate for your field.
Frequently Asked Questions
Should I apply zinc to the soil or spray it on leaves? Both work. A basal soil dose of monohydrate builds zinc for the whole season and carries over, while a foliar spray of heptahydrate corrects a visible deficiency quickly. Many growers use both.
Which zinc sulphate grade is best for foliar spray? Zinc Sulphate Heptahydrate at 21% or 22% zinc dissolves quickly and sprays easily, which makes it the preferred grade for a 0.5% foliar solution.
How much zinc sulphate does soil application need? A common basal rate is about 20 to 25 kg of Zinc Sulphate Monohydrate per hectare, but the exact rate depends on your soil test and local agronomy guidance, so confirm before large scale use.