Calcium Ammonium Nitrate (CAN)

Calcium ammonium nitrate is ammonium nitrate diluted with ground limestone or dolomite. The carbonate is worked into the melt until the nitrogen comes down to about 27%, which has three effects. It puts the product below 28% nitrogen from ammonium nitrate, the line at which an EU fertilizing product becomes an ammonium nitrate fertilizer of high nitrogen content and picks up detonation-resistance testing and the controls that go with it. It makes the fertilizer non-acidifying, because the carbonate neutralises what the ammonium half would otherwise acidify. And it adds calcium, which several crops want anyway. Agronomically it complements urea: half the nitrogen is nitrate and available the moment the granule dissolves, there is no urease step and so no ammonia volatilisation to manage, and it keeps working in cold soil where urea is slow. Ehlinar supplies CAN 27 and regional grades, including dolomitic grades carrying magnesium.

Appearance: White to light grey or pale beige granules, typically 2–4 mm, surface-treated with an anti-caking coating. Hygroscopic, and appreciably heavier in the bag than urea — bulk density usually falls around 0.95–1.05 t/m³ against roughly 0.75 for urea, which changes spreader settings and store capacity alike.

Applications

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Also known as

CAN · CAN 27 · KAN · Ammonium calcium nitrate · Nitric acid, ammonium calcium salt · Nitrochalk (historic trade name) · Nitro-limestone

Frequently asked questions

Is CAN the same thing as calcium nitrate?

No, and the two are confused constantly because both are sold as calcium-bearing nitrogen. Calcium ammonium nitrate is ammonium nitrate blended with ground limestone or dolomite, around 27% N, and the carbonate in it does not dissolve. Calcium nitrate is a different salt — around 15.5% N with roughly 19% calcium, fully water-soluble — and it is the one that goes into fertigation and hydroponics. To complicate it further, a hydrated double salt of calcium nitrate and ammonium nitrate is also called calcium ammonium nitrate and shares the same CAS number, and that material is soluble and behaves like calcium nitrate. If solubility matters to your application, say so in the enquiry rather than relying on the name.

Why is CAN made at 27% nitrogen and not higher?

Because 28% is a regulatory line, not a technical one. An EU fertilizing product with 28% or more nitrogen by mass coming from ammonium nitrate is classed as an ammonium nitrate fertilizer of high nitrogen content and has to demonstrate resistance to detonation, with the oil-retention test and the additional controls that accompany it. Sitting at 26–27% keeps a product clear of that regime while giving up very little agronomically, so that is where the industry standardised. The same dilution is what makes CAN easier to store and to ship than straight ammonium nitrate.

How does CAN compare with urea?

Per tonne of product urea carries far more nitrogen — 46% against 27% — so it is cheaper to ship, store and spread per unit of N, and under warm, moist, well-managed conditions the two perform about the same. CAN wins precisely where urea is weak: surface application with no incorporation and no rain to follow, cold soils early in the season, and high-pH or calcareous ground, all of which push urea's nitrogen into the air as ammonia. CAN also supplies calcium and does not acidify. In practice many programmes use both — urea for the bulk of the nitrogen, with a urease inhibitor where it is surface-applied, and CAN for top-dressing and for the fields where the loss risk is real.

Is CAN a dangerous good to transport?

Usually not, and that is by design. A grade holding no more than 80% ammonium nitrate mixed with limestone or dolomite, with no more than 0.2% combustible organic material, ships as a non-hazardous ammonium nitrate based fertilizer — which is where the standard 27% product sits. Raise the ammonium nitrate content, or let organic material in through packaging, pallets or contamination in a hold, and the classification changes, typically to UN 2067, Class 5.1. The composition on the certificate is what decides it, so confirm the classification for the specific grade and route before booking freight.

Can anyone buy calcium ammonium nitrate?

Not in the EU, and not in most jurisdictions that have followed it. Ammonium nitrate above 16% nitrogen in relation to the ammonium nitrate content is a restricted explosives precursor: it cannot be made available to members of the general public, while professional users — farmers and industrial buyers — may continue to purchase it. In practice that means an order needs company identification and a stated agricultural or industrial end use, and a supplier is expected to decline anything that does not supply them and to report suspicious approaches. Treat the paperwork as part of the transaction rather than an obstacle to it.

Why does CAN cake, and what can be done about it?

Ammonium nitrate is strongly hygroscopic and it also changes crystal form as it passes through about 32 °C, so a stack that warms in the day and cools at night is being worked mechanically from the inside. Moisture taken up in humid air then bridges the granules as it dries. The defences are all practical: an intact anti-caking coating, dry covered storage on a dry floor, stack heights within the supplier's recommendation, keeping the product out of day-night temperature swings, and moving stock rather than letting it sit through a season. Never store it next to urea — a dry mixture of the two takes up water at a humidity well below what either survives alone.