Calcium ammonium nitrate (CAN)

Calcium ammonium nitrate (CAN) is a straight nitrogenous fertiliser manufactured by incorporating calcium carbonate — finely ground limestone or dolomite — into an ammonium nitrate solution, followed by granulation or prilling of the blend. The nitrogen content typically ranges between 21% and 26%, half in ammoniacal form and half in nitric form^[1][2]. The presence of carbonate gives the product a non-acidifying effect on soil, unlike pure ammonium nitrate^[1][2]. The lower nitrogen concentration compared with prilled urea (46%) or concentrated ammonium nitrate (33.5%) represents a drawback for long-haul transport^[1][3].

Manufacture and process

CAN production forms part of nitrate manufacturing units, which generally process anywhere from a few hundred to 3,600 tonnes per day^[4]. The process involves neutralising nitric acid with ammonia to form ammonium nitrate, then mixing the resulting solution with calcium carbonate before converting it into solid form. European installations recorded in 2006 had capacities ranging from 75 kt/year to 1,150 kt/year^[4]. The table from that date notably lists the DSM plant at Geleen (Netherlands), with a capacity of 1,150 kt/year, as well as several two-line sites such as Yara's facility at Rostock (Germany), with two units of 633 kt/year each^[4]. The product complies with European Regulation 2003/2003/EC relating to fertilisers^[4]. Where the ammonium nitrate content exceeds certain regulatory thresholds, the product is classified as an oxidising substance under United Nations transport regulations^[4].

Agronomic uses

CAN application does not cause soil acidification, thanks to the buffering action of the calcium carbonate it contains^[1][2]. The nitrogen fraction, half ammoniacal and half nitric, provides immediate availability to the plant (nitric form) alongside more gradual release (ammoniacal form, following nitrification). This dual form makes it a versatile fertiliser, used as a basal or top dressing on numerous crops. Indian specifications set the minimum total ammoniacal and nitric nitrogen content at 25.0%, and the maximum moisture content at 1.0%^[2]. CAN must not be confused with calcium nitrate (Ca(NO₃)₂, 15.5% nitrogen), used mainly on cash crops for its soluble calcium supply^[3].

Market and trade

World nitrate (AN/CAN) production stood at 19.1 Mt of nitrogen in 2023, including 3.5 Mt for CAN and magnesium ammonium nitrate (MAN); these figures incorporate the nitric portion of urea-ammonium nitrate solutions (UAN) as well as industrial grades^[3]. Over the period 2013-2023, the trend growth of nitrate production was flat^[3]. Russia ranks as the world's leading producer, followed by the United States and China^[3]. Nitrate consumption remains firmly rooted in Europe, where CAN is the most widely applied fertiliser^[4][3]. The lower nitrogen concentration relative to urea constitutes a logistical handicap: the ratio of fertiliser mass transported per unit of nitrogen is less favourable, which penalises intercontinental flows^[3]. Commercial exchanges therefore concentrate on regional zones, with Europe remaining the principal consumption basin.

Regulation and safety

CAN benefits from a regulatory status distinct from that of pure ammonium nitrate, whose trade and agricultural use are banned in numerous countries owing to explosion risks^[5]. The addition of calcium carbonate reduces the ammonium nitrate fraction and thereby lowers the product's hazard level, whilst preserving its fertilising properties^[5]. Nevertheless, ammonium nitrate content thresholds remain monitored for transport classification purposes^[4]. In Europe, the Fertilising Products Regulation governs the specifications of fertilisers placed on the market, although the provisions relating to cadmium concern phosphate fertilisers more than nitrates.