The main part of the Onuku Maori Lands' Trust land is located on Rerewhakaaitu Rd and State Highway 38 and contains about 2364 hectares.
Mahuta said research conducted in 2011 estimated that around 80 per cent of whenua Maori was under-utilised or under-performing.
"Ongoing support programmes and pending legislative changes would assist with improving the situation for Maori. I'm keen to see us doing a lot better."
Agriculture Minister Damien O'Connor was also at the announcement.
"We are seeing great developments in all productive sectors and a trend for Maori to play an increasingly significant role in producing higher value food products. The rise and rise of Maori agribusiness is impressive, especially given its unstinting commitment to all aspects of sustainability, particularly the environment and people."
The winner of the Ahuwhenua Trophy will be announced at an awards dinner at the Wigram Airforce Museum in Christchurch on May 25.