Balchin has won junior titles in the past but this was the big one and his first provincial senior men's title.
Balchin (20), the youngest runner in the field, won the race to the tape in a time of 8min 25.26sec.
Callan Moody (Ariki) was second in 8min 26.26sec and Dougal Thorburn (Ariki) third in 8min 38.97sec.
The first two runners ran personal-best times - Balchin by 13sec and Moody by 6sec.
It was the day that Balchin came of age as a middle-distance runner.
He did everything to perfection and timed his moves like clockwork.
The first two laps were pedestrian but Thorburn then gingered up the pace by running 65sec for the third lap and followed it up with a smart 64sec.
There were only three runners left at the front after this.
"The race needed pace after the slow start and I did not want to let them get away," Balchin said.
"I had to stay with the pace."
Balchin and Moody were content to let Thorburn keep the lead and the pace slowed to 67sec and 69sec over the next two laps.
Balchin waited for his chance.
"I had to save a bit for the last lap," he said.
"I knew that Callan had a good kick finish."
The Caversham runner was ready to react when Moody made his move just before the bell and tore down the back straight.
Thorburn was dropped and it was an all-in battle between Moody and Balchin.
No quarter was given and Moody held his edge around the final bend.
But Balchin was on his heels and pounced in the front straight.
"I made sure that I stepped into my after-burner with 100 to go," Balchin said.
He caught Moody 60m out and edged in front with 40m left.
"Callan didn't speed up when I went past," Balchin said.
"I realised then that the race was mine."
Rebekah Greene (Hill City) finished fifth in the race in 9min 35.28sec and won the women's title.
Dalise Sanderson (Ariki) finished third in the masters women's event and broke her own Otago aged 55 to 59 record by 18sec in 12min 06.12sec.
The other feature event on the programme was the men's 400m won by Andrew Moore (Hill City) in 47.36sec from club-mate Daniel O'Shea in 48.42sec and Andrew Whyte (South Otago) in 49.61sec.
It was Moore's first 400m race since racing in Europe in the winter of 2009.
He won the New Zealand senior men's title earlier that year and wants it back at the championships at Dunedin next month.
His time lifted him to second spot on this season's national ranking behind Alex Taylor (Tasman) who has run 47sec flat.
Moore's best time is 46.95sec.
The other feature event was the women's triple jump won by Greer Alsop with a Southland girls aged 16 record of 11.93m.
It was a personal best by 24cm.
Fellow Southland jumper Charlotte Muschamp was runner-up with 11.81m.
It was the highest standard of triple jumping seen at the Caledonian Ground for more than a decade.
This was understandable because Alsop won the Oceania junior title at Cairns last October and Muschamp was third.
Alsop (16) and Muschamp (18) head the national ranking list in women's aged 16 and women's aged 19 grades.
Roseanne Robinson (Hill City) won the women's 3000m walk in 14min 49.36sec and her club-mate and defending New Zealand champion Anna Smythe won the women's 100m in 11.92sec.
In the throwing events, Hamish Finnie (Hill City) won the men's 19 shot put with a personal-best 14.83m and Jesse Porter (Hill City) improved by 2.57m when he won the men's 16 javelin with 49.95m.
Club-mate Bryn Jones improved by 2.99m in finishing second with 48.98m.
