It happened at Ashlan and McCall Avenues, east of Clovis, just before 5:30 am.
Officials say a tractor with a spray rig was eastbound on Ashlan near the shoulder of the road when the CHP officer hit it from behind.
The officer and his motorcycle ended up in the orchard on the north side of the road, the CHP said. He was taken to Community Regional Medical Center for surgery and is expected to survive.
Authorities say the officer was on duty and was responding to an area office at the time of the crash.
The tractor operator was not injured and is cooperating with the investigation.
Officers blocked off part of Ashlan Avenue between McCall and Del Rey for several hours for the investigation.