The Swede has denied accusations that he belongs to the militant Islamic group Hezbollah, citing an Israeli conspiracy and claiming that the fertiliser was planted.
"The accused hid bomb material which is illegal and which could constitute a security risk, but since he has cooperated with the authorities the punishment is reduced from four years to two years and eight months," the judge said according to Reuters.
"He will be held in prison for a year since he has already spent a year and eight months there," lawyer Witthaya Buranasil told news agency TT.
Buranasil said the ruling will be appealed.
The man previously worked as a hairdresser in Gothenburg. When he was arrested at the airport in Bangkok on January 12th, there were strong reactions from the US and Israel, two of the countries which have labeled Hezbollah a terrorist organisation. The European Union has since added the military wing of Hezbollah to its terror list.
The US and Israel claimed they had information that Hezbollah had plans to blow up a Jewish centre and tourist spots in Bangkok that are popular among Israelis and Americans.
At first, Thai authorities suggested that the Swede could be involved in the plot, but later said that if the fertiliser were to be used for malicious purposes then it would not be in Thailand as it was due to be exported.