Calcium Nitrate (15.5-0-0 + Ca)
Quick nitrate nitrogen plus the calcium that stops blossom-end rot — a fertigation and foliar favourite on fruit and vegetables.
- Composition
- 15.5% N (nitrate), 19% Ca
- Form
- Water-soluble granules
- Price
- Premium (non-subsidised)
- Best for
- Calcium disorders; fruiting stage
Overview
Calcium nitrate carries 15.5% nitrogen, almost all as fast-acting nitrate, along with 19% calcium — and it is fully water-soluble. Its value is the calcium: many fruit and vegetable disorders (blossom-end rot in tomato and capsicum, tip-burn in cabbage and lettuce, bitter pit in apple, cracking) are calcium-deficiency problems, and calcium nitrate is the standard soluble source to prevent them.
It is a fertigation and foliar product, not a bulk field fertiliser. Because it reacts with phosphate and sulphate fertilisers to form insoluble solids, it must be kept in its own stock tank and never mixed directly with them.
What it is and when to reach for it
- A soluble nitrate-nitrogen fertiliser whose real job is supplying calcium — reach for it on fruit and vegetables prone to blossom-end rot, tip-burn or cracking.
- Its nitrate nitrogen is taken up fast and does not acidify the soil the way urea and ammonium do.
- It is a fertigation/foliar product for high-value crops, not a cheap field nitrogen source.
How to use it well
- Fertigation: apply through the drip from early fruiting, when calcium demand and blossom-end rot risk peak.
- Foliar: a dilute spray (around 0.5–1%) at fruit set supplements calcium where root uptake is limited by dry or erratic watering.
- Keep watering steady — calcium moves with water, so uneven irrigation causes deficiency even when soil calcium is adequate.
Common mistakes
- Tank-mixing it with phosphate (MAP/DAP) or sulphate fertilisers — they react and form an insoluble sludge; use separate stock tanks.
- Relying on a foliar spray to fix a disorder caused by erratic irrigation rather than fixing the watering.
- Using it as a general field nitrogen source, where cheaper urea does the nitrogen job.
Organic alternative
Gypsum + steady irrigation
In organic systems, gypsum supplies calcium and even, unbroken watering is the real fix for blossom-end rot and tip-burn.
Crops it is used on
Open a crop for its full nutrient schedule.
Common questions
Does calcium nitrate stop blossom-end rot?
It helps, but the root cause is usually irregular watering that stops calcium reaching the fruit, not just low soil calcium. Steady irrigation plus calcium nitrate through the drip or as a foliar spray at fruit set is the reliable combination for tomato, capsicum and similar crops.
Can I mix calcium nitrate with other fertilisers?
Not with phosphate or sulphate fertilisers — they react with the calcium and form an insoluble sludge that blocks drippers. Keep calcium nitrate in its own stock tank. It can be alternated with other solubles, just not combined directly with those two groups.
Is calcium nitrate a good nitrogen fertiliser?
Its nitrogen is fast-acting nitrate and does not acidify the soil, which is useful, but at 15.5% N and a premium price it is not an economical field nitrogen source. Buy it for the calcium and the fertigation convenience, not to replace urea.
Composition and doses follow ICAR / Soil Health Card guidance; prices are the notified subsidised rates for the season shown and are guidance, not a quote. A soil test for your field always beats a general rate. See our editorial policy.