Hertfordshire Police said two men were arrested on suspicion of public order offences during the demonstration at Rothamsted Research at Harpenden.
They were arrested under Section 14c of the Public Order Act, which stops people from holding "an assembly" on a prohibited area of land.
There's a heavy police presence at at Rothamsted Research in Harpenden after protestors planning action over a genetically modified wheat trial there were banned from going anywhere near the crop.St Albans council has secured extra police powers to stop them going on to the land.
The media have been given a guided tour of the land where genetically modified wheat trials are being carried out. A group called Take the Flour Back are due to protest over the open air trials of genetically modified wheat.
Rare coins including one with an image of Colonel Gaddafi have been stolen from a house in Harpenden in Hertfordshire.
It happened sometime between Saturday 11 February and the Saturday 18 February on Piggottshill Lane, where someone forced entry through the front door.
The gold coloured commemorative Gaddafi coin is in a small red coin box and has Arabic writing. The second coin is a silver football medal from 1970 with, ‘British University Soccer Federation Cup’ written on one side.
DC Andy Greenman, who is investigating the burglary, said: