Anya Kamenskaya, a spokeswoman for the group, said protesters didn't plan to re-occupy the Gill Tract and only wanted to be there a short time to harvest crops that they allege are being overgrown with weeds.
Kamenskaya said, "We're weeding the crops here as fast as we can because UC is not taking care of them and plants are choked with weeds."
Kamenskaya said about 75 activists entered the plot of land, which is located near the corner of Marin and San Pablo avenues, about 9:40 a.m. today and about 50 people remained there as of noon.
UC Berkeley spokesman Dan Mogulof said university police issued a warning to the activists this morning but they left early this afternoon "with no arrests, no confrontations and no damage to the research crops."
Occupy the Farm activists began an action at the plot of land on April 22, which is Earth Day, to protest development plans by UC Berkeley and the city of Albany.
The protesters alleged that UC planned to replace the current agricultural land with commercial, recreational and open space.
But university officials said the existing agricultural fields would continue to be used as an open-air laboratory by the students and faculty of the College of Natural Resources for agricultural research.
They said the parcel of land slated for development is to the south of the Gill Tract, at Monroe Street and San Pablo Avenue. That land hasn't been farmed since World War II, according to the university.
The protest ended on May 14 when UC police arrested nine protesters.
Kamenskaya said Occupy the Farm activists returned to the Gill Tract today because they were upset that UC and Albany officials were planning an invitation-only harvesting party at the site. The party was canceled on Thursday after protesters learned about it and it was publicized, she said.
"It was entirely secret because UC and the city of Albany didn't publicize it," Kamenskaya said.
Kamenskaya said Occupy the Farm activists will mobilize again on Monday night, when the Albany City Council will holed another public hearing on development plans for the area near the Gill Tract.
She said activists will hold a rally at 6 p.m. Monday and the council meeting is scheduled to begin at 7:30 p.m.