Ferguson ended with 5-68, making a big impact with both legal and illegal deliveries to increase Auckland's grip on the title.
Canterbury blew a golden opportunity to keep in touch, failing to chase down 184 against Wellington at Hagley Oval.
In a chaotic encounter, a catastrophic collapse saw Wellington fall from 73-0 to 136 all out, leaving Canterbury a session to chase down 184.
The target looked in sight at 51-1 after 13 overs, but a rash of wickets started a slump which they couldn't recover from, eventually bowled out for 129.
The win saw Wellington leapfrog Canterbury on the ladder, with the two sides joining Auckland as the only teams with a mathematical chance at the title.
Elsewhere, a career-best unbeaten 166 from Tom Bruce wasn't enough for Central Districts to chase down a record 498 against Northern Districts at Seddon Park.
Resuming the day at 64-3, Central looked dead and buried at 176-6, requiring another 322 runs for victory.
However, Bruce found a partner in Bevan Small, with the seamer flying past his previous top score of 29 in a resolute 76.
The pair added 177 for the seventh wicket, but just as a remarkable record loomed, the ND spin duo of Joe Walker and Anton Devcich struck, giving the hosts their second victory of the campaign.
The penultimate round begins next Wednesday, with Wellington hosting Auckland in a game which could decide the title.
