Advice on storing fertiliser safely

17 August 2020

Farm business Farm safety

NFU farm safety and transport adviser Tom Price provides a useful reminder on how to store fertiliser safely.

Ammonium nitrate (AN) fertiliser is an essential and valuable input into farming businesses. Under normal circumstances ammonium nitrate (AN) fertilisers are stable materials. However, under abnormal conditions AN fertiliser can produce hazards:

  • AN fertilisers are oxidising agents – this means that they can accelerate the combustion of other combustible materials even when no oxygen is present.
  • AN fertilisers can release toxic fumes when subject to thermal decomposition
  • Under extreme conditions AN fertilisers can explode

Safe Storage

Whenever possible fertiliser should be stored inside a secure building made from non-combustible materials. The building should be dry, well ventilated and with a floor free of sharp objects.

When storing fertiliser inside a building:

  • Stack to a maximum of 3 bags high. Interlock bags in a stack for stability
  • Keep each stack to a maximum of 300 tonnes. Have a 1 metre gap between stacks
  • Take extra care when dismantling a stack if a bag is damaged
  • Store well away from combustible materials such as hay, straw, fuel and oil
  • Keep well separated from other chemical substances such as urea, pesticides, corrosive liquids and lime
  • Keep stores clean, tidy and secure. Inspect regularly
  • Absolutely no naked fames and no smoking

If AN fertiliser needs to be stored outside:

  • Use a level, fenced and secure area to help stop unauthorised access
  • Stack off the ground on pallets
  • Fully sheet and check the stack regularly
  • Notify the HSE and the fire service

Dangerous substances

  • Your local HSE and local fire service must be notified if 25 tonnes or more of a dangerous substance are stored on a site. AN fertiliser with a nitrogen content of 28% and over is classed as a dangerous substance.
  • A copy of the notice that is required under the Dangerous Substances (Notification and Marking of Sites) Regulations 1990 (NAMOS) regulations is available from the HSE website here.
  • A list of HSE offices to send the notification form to is available here.
  • A list of fire service offices to send the form to is here.
  • All sites where dangerous substances are stored must be marked with the appropriate signage.
  • Guidance on the notification and marking of sites is available in HSE guide INDG 467 and in HSR 29.

150 tonnes or more of any fertiliser

If 150 tonnes or more of any type of fertiliser are stored on a site, the local fire service should be notified using the same Namos form as used to notify of the storage of 25 tonnes or more of a dangerous substance.

More information:

  • A HSE check list is available here to help you assess whether sufficient steps have been taken to ensure the safety and security of stored fertiliser.
  • More detailed guidance from the HSE is in the guide INDG230 available here.
  • Guidance from AIC on the essentials for the safe storage of solid and liquid fertilisers is available here.

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