Dubbed the southern hemisphere's largest pony club event, the Springston Trophy brings together clubs from around the South Island.
Forty teams and 210 riders will contest the 2018 event, hosted by the North Otago Pony Club at the Oamaru Racecourse.
The 24-year-old Ms Allison, who will ride for the Dunedin Branch Pony Club's white team this year on Mustang Shelby, competed in her first Springston Trophy in 2003 as a 9-year-old.
She has missed only one event since then, in 2010, when she underwent back surgery 10 days before the competition.
After two top-10 finishes in 2011 and 2013, and a horse mastership title with her team in 2012, Ms Allison was hoping for another solid finish this year.
"We are aiming definitely for a top-10 finish, but it's more about having fun. You want to see all of the riders out there having fun and enjoying it.
"I love seeing young riders and also young horses figuring out what they can do and how they can excel. It always pays off a lot more when you can train the young horses and they just click.''
Ms Allison, the club's event secretary and cross-country course designer, is not competing for the final time by choice, but because of the age restriction placed on competitors.
However, she planned to remain involved with the sport in a different capacity
"After this year I am too old. It's a bit sad, but from now I'll be carrying on into more of a coaching role. I'll still be there supporting everyone else.''
Club president Leah Wilson said it was believed Ms Allison's 15 Springston Trophy appearances were a record and to recognise her achievement, she will be presented with a special award at the conclusion of the event.
The event begins at 9am tomorrow with the dressage.
