A 56-year-old man suffocated Tuesday morning after his arm got caught in a machine at the plant nursery where he worked.

Manuel Moreno, of Valley Center, was found by a co-worker trapped in the conveyor belt of a machine that sorts soil at Evergreen Nursery, 3231 Oceanside Blvd. Moreno is believed to have died sometime between 8:15 a.m. and 8:58 a.m., Oceanside police officer Ernie Thibodeaux said. Police responded to the scene at 9:01 a.m., he said.

An early investigation suggests Moreno slipped while attempting to jump from the machine to the seat of a front-end loader he had been driving, Thibodeaux said. When he fell, his arm got caught in the conveyor belt and wrapped around the wheel on which the belt turned, he said.

The belt pulled Moreno's body forward, forcing his head against another part of the machine and pinning his face into his shoulder so that he could not breathe, Thibodeaux said.

Moreno had been working at the nursery for more than 20 years, and using the machine was his main job, Thibodeaux said. He said employees reported hearing him turn on the machine at 8:15 a.m.

Krisann Chasarik, a spokeswoman for the California Division of the Occupational Safety and Health Administration, said there have been no safety violations reported at the business in the past seven years. She said inspectors visited the wholesale nursery's San Diego location in August 2008, and did not find any violations.

Evergreen Nursery has locations in Carmel Valley, Rancho Bernardo and Oceanside, according to the business' website.

Call staff writer Morgan Cook at 760-739-6675.