The trust announced last night it would grant $7 million to the Dunedin City Council should the stadium proceed, not the $10 million requested.
Chairman Bill Thomson said the trust was unable to approve the full amount requested because the downturn in global financial markets had significantly depleted the trust's reserves this financial year.
"The trust was mindful of the downturn, alongside its ongoing donation programme for a wide range of organisations."
The Dunedin City Council will make a final decision on the project on Monday, and the Otago Regional Council will decide on Wednesday.
The $10 million trust grant was part of the regional council's conditions in approving its $37.5 million contribution to the project.
ORC chairman Stephen Cairns said the $3 million gap would have to be "picked up somewhere, somehow, potentially".
Dunedin Mayor Peter Chin echoed Mr Cairns' comments and said the $3 million shortfall would be another factor councillors would have to take into consideration on Monday.
Both men said that given the trust's other responsibilities and the present economic climate, the decision was understandable.
Carisbrook Stadium Trust (CST) head Malcolm Farry said CST had faced many challenges in getting this far, and finding another $3 million was "just another one".
The donation from the trust was very generous and CST, "as the whole community should be", was extremely grateful.
"By my reckoning, this is $5 million more than any other grant they've given, so that gives a strong indication of how they see the project."
The trust warned it would have to cut back its grants in November, after global economic turmoil saw its capital reserves drop dramatically during 2008.
Mr Thomson said the application met the trust's established criteria for community project investment.
"We believe the stadium will become a major asset for the city and the region offering significant long-term opportunities. The potential benefits for the University [of Otago], given its proximity to the stadium, will be valuable to both the university and the stadium itself."
The trust might have to scale back grants for larger capital projects over the next few years, but small- and medium-sized grants would be not be affected either by the reserves depletion or the stadium grant, he said.
Stop the Stadium president Bev Butler said she was disappointed the trust intended to grant money to the project at all and hoped the regional council would stick to its conditions.
