The head of the investigation into the murder of Feilding dairy farmer Scott Guy says a roadside and "environs search" for the shotgun that killed him is under way.

Inspector Sue Schwalger this morning spoke to media outside the 31-year-old's house where he was gunned down before 7am last Thursday.

A team of search and rescue workers are searching the bush around the Oroua river.

Police earlier stopped motorists in the area in an attempt to track down potential witnesses to the homicide.

Ms Schwalger said about 80 motorists were stopped.

The five road blocks around Aorangi Rd - which started at 4.30am and finished at 8am - were kept secret from residents in order to identify regular road users in those hours on a Thursday.

After catching early-morning farm-workers leaving the area, the check-points were reduced to four.

Police filled out a questionnaire for each motorist, asking them things like: "Do you regularly use this route?", "Did you use this route last Thursday?" and "Are you aware of Scott's death?"

Drivers were then handed a leaflet with a photo of Mr Guy, the date of the murder and phone numbers for the investigation team.

Ms Schwalger said police were yet to find a motive for the killing.

There had been minimal response from members of the public despite a phone number set up for the homicide.

Mr Guy is to be farewelled at a service tomorrow at the St John Evangelist Anglican Church in Feilding, followed by a private burial.

The church will cater for the large numbers expected by broadcasting the service outside on a large-screen television.

Mr Guy left behind wife Kylee, who is pregnant with a second child due in September, and two-year-old son Hunter.

* Anyone with information on the homicide can phone the Palmerston North police on 0800 808 585 or the Crimestoppers number anonymously on 0800 555 111.