More than 90% of terrorist attacks in the UK have used home-made explosives, the majority of which have been fertiliser-based, police officers have said.
Counter-terror police are talking to farmers about the risk of leaving fertiliser insecure as counter-terrorism awareness week enters its fifth day.
Forces are also issuing guidance on storing firearms safely to prevent guns from being stolen by potential terrorists. Over the last five years, an average of 659 firearms, shotguns and certificated items were lost or stolen each year.
Earlier this week, a new Counter-terrorism and Security Bill, containing a range of draconian powers including new orders that can block suspected British fighters from returning to the UK, was introduced to Parliament.
And a report from the Intelligence and Security Committee (ISC) into the murder of soldier Lee Rigby sparked a row over the capabilities of the secret services after social networking site Facebook took the brunt of criticism for failing to flag a gruesome chat between one of his killers and an overseas extremist.
National policing lead for gangs and criminal use of firearms, Deputy Chief Constable Dave Thompson, said: " We want to stop terrorists getting access to tools that they can use against UK citizens.
"We need to make sure licensed gun-owners are securing their guns properly and remove guns from our streets and criminal networks so that terrorists cannot take advantage of them.
"These operations won't impact on conscientious and responsible firearms licence-holders but they will help to prevent weapons getting into the wrong hands.
"We are making sure that those who handle large quantities of fertilisers understand how they can help us to prevent a terrorist attack through simple security measures.
"Terrorists can use ordinary objects such as kitchen knives and other items as weapons so we need people to report any concerns they have about anyone who is showing signs of extremism.
"If you suspect it, report it. We can then intervene early and help. Your piece of information could hold the key."