It was about what this potentially might mean in terms of investment strategy going forward, he said.
''That led to being shoulder-tapped to being a part of the initial group and it's progressed from there, really.''
DLAG had now been running for about three years, and had started through sending dairy farmers to the Dairy Environmental Leaders Forum about five years ago.
Each year two different people travel to the forum, and bring a range of new ideas back to the Southland DLAG group.
Last month, Mr Mathieson took on the chairman role, replacing Raewyn van Gool, who was the group's chairwoman since it began.
''I can see real value in the group,'' he said.
Originally the Mathieson farm, near Colac Bay in Western Southland, was sheep and beef.
There were three reasons behind converting to dairy - the capital values, the opportunity to expand and also succession.
''Change gave us the opportunity to buy the neighbour's property and give our children the opportunity to be a part of the business.''
This transpired to his work with DLAG and wanting to get other people involved.
One of the main priorities for DLAG was getting the wider community engaged in what they were doing.
''It's about bringing people on board with the changes and getting them to understand it's not all just about compliance.''
Lowering environmental impact through methods such as nutrient levels and greenhouse gases had other spin-off benefits in terms of marketing, Mr Mathieson said.
It was about getting people to understand the bigger picture and how it could all work, and relating it back to the consumer, he said.
''All we're doing is endeavouring to [get] them engaged in what's happening. They will implement what they need to in their business.''
Mr Mathieson works at liaising with DairyNZ, and had also met with Minister of Agriculture Damien O'Connor, as well as local government members.
His biggest focus was on investment strategies and getting people to realise they could not invest in the same way anymore with the changes happening in the primary sectors, he said.
Not all farms could be converted going forward, and other implications would soon be in place, and farmers needed to be informed in order to make wiser decisions, Mr Mathieson said.
Southern Rural Life