Published 29 April 2026

Ammonium Nitrate Fertilizer: IMSBC Code Schedule and Carriage

Contents

Ammonium nitrate fertilizer is a major dry bulk cargo with global seaborne trade of approximately 15 to 20 million tonnes per year. It is shipped principally as straight ammonium nitrate or as ammonium nitrate-based blended fertilizers from major producing regions including Russia, Egypt, Trinidad and Tobago, the United States, China, and Eastern Europe to agricultural markets worldwide. The cargo is regulated under the International Maritime Solid Bulk Cargoes Code (IMSBC) as a Group B chemical hazard and is one of the most strictly handled fertilizer cargoes due to its oxidising properties and well-known catastrophic decomposition risk under fire and contamination conditions.

Schedule structure

The IMSBC Code includes several distinct schedule entries reflecting the different commercial grades of ammonium nitrate fertilizer:

Ammonium nitrate (UN 1942): high-purity ammonium nitrate (above 80 per cent NH4NO3 by mass). Strong oxidiser and Group B chemical hazard. Subject to strict carriage requirements.
Ammonium nitrate based fertilizer (UN 2067): blended fertilizers containing ammonium nitrate plus other components, typically 70 to 80 per cent ammonium nitrate. Group B with handling requirements similar to UN 1942.
Ammonium nitrate based fertilizer (Type C, IMSBC schedule): lower-purity blends with reduced oxidising properties. Group C in some classifications.

Most marine shipments are UN 1942 or UN 2067 grades. The cargo is also subject to the IMDG Code where carried in packaged form rather than in bulk.

Hazard properties

Ammonium nitrate is a strong oxidiser, releasing oxygen on decomposition that supports combustion of organic and other reducing materials. The compound is generally stable at ambient temperatures but undergoes increasingly rapid decomposition above 170 degrees Celsius:

170 to 200 degrees Celsius: slow decomposition with release of nitrogen monoxide and water vapour.
200 to 250 degrees Celsius: accelerated decomposition with release of nitrous oxide.
Above 250 to 300 degrees Celsius: thermal runaway and potential detonation, particularly under confinement or in the presence of contaminants such as oils, organic dust, sulphur, chlorides, copper, or other metals.

Ammonium nitrate has been involved in multiple catastrophic explosions, including the 1947 Texas City disaster (581 deaths), the 2001 AZF Toulouse plant explosion (31 deaths), and the 2020 Beirut port explosion (218 deaths). Marine carriage incidents have been less frequent but include the 1947 SS Grandcamp loss at Texas City and several smaller fires. Strict IMSBC handling discipline and pre-loading inspection are designed to prevent these incidents.

Handling and carriage requirements

The IMSBC schedule for ammonium nitrate fertilizer prescribes:

Hold cleanliness: holds must be thoroughly cleaned of oils, organic dust, and other contaminants. Previous cargo of coal, sulphur, or other reducing materials requires comprehensive cleaning before ammonium nitrate can be loaded. Class society and shipper cargo surveyors typically inspect and certify hold cleanliness.
Steel surface protection: cargo holds should have intact paint coatings to prevent direct contact between ammonium nitrate and bare steel. Some grades of ammonium nitrate can corrode bare steel and form copper-ammonium-nitrate compounds with copper alloys, both of which are dangerous.
Temperature monitoring: cargo temperature should be monitored throughout the voyage. Significant temperature rises (above approximately 50 degrees Celsius) warrant emergency response.
No smoking and no hot work: smoking, welding, cutting, and other ignition sources are strictly prohibited in or near cargo holds during loading, voyage, and discharge.
Segregation: ammonium nitrate must be segregated from incompatible cargoes including organics, sulphur, chlorides, copper, lead, and other hazardous materials. Adjacent holds should not contain incompatible cargoes.

Fire response

Conventional fire-fighting on ammonium nitrate cargo fires is highly hazardous. The cargo’s own oxidiser content sustains combustion even in the absence of atmospheric oxygen, and inert gas fire suppression (CO2, N2) is largely ineffective. The recommended response under the IMSBC Code and cargo industry guidance is:

Apply large quantities of water to cool the cargo and prevent thermal runaway.
Ventilate to release nitrogen oxide decomposition products and prevent confinement.
Evacuate non-essential personnel from the cargo area.
If thermal runaway cannot be controlled, abandon ship and allow the cargo to vent or detonate at distance from human populations.

The Beirut 2020 explosion illustrated the catastrophic consequences of incorrect fire response: a fire in adjacent stored fireworks heated approximately 2,750 tonnes of confiscated ammonium nitrate stored without proper segregation, leading to detonation of an estimated 600 to 1,000 tonnes equivalent. Marine carriage discipline and port handling discipline have been substantially tightened in response.

Major routes

Ammonium nitrate fertilizer seaborne trade flows include:

Russia (Murmansk, Saint Petersburg, Novorossiysk export terminals) to Brazil, the EU, and global agricultural markets.
Egypt (Alexandria, Damietta) to Africa and Asia.
Trinidad and Tobago (large URC and YARA production) to North America and Latin America.
United States (export from Gulf and East Coast plants) to Latin America.

Russia is the largest single exporter of ammonium nitrate fertilizers, accounting for approximately 30 to 40 per cent of global seaborne trade depending on year and sanctions context.