They know what their greenhouse gas emissions are, how much carbon the trees on their property are sequestering and have 30 years of soil test data to draw on.

Yet they will never dabble in the carbon market and none of what they've put in place has been driven by chasing ESG - environmental, social and governance - credentials.

It's all been about efficiency, productivity, profitability, long-term sustainability and enjoying the farming environment.

The couple both have degrees in agricultural science and make their farm management decisions based on data and proven best practice.

They run a self-replacing fine wool Merino flock and performance-recorded commercial Angus herd at Knewleave, near Geelong on the Bellarine Peninsula in Victoria.

Their 400 hectares of both owned and leased country is all improved perennial-based pasture such as phalaris, fescue and ryegrass which receives an average annual rainfall of 600mm.

They started taking soil samples the day they started farming and have done so for a third of the farm every year since.

Such an enormous bank of soil test data covering the entire property is likely one-of-a-kind in Australia but it's information the couple have been able to draw on to make management decisions that have allowed for a doubling of stocking rates over that period.

They also started a tree planting program three decades ago.

Initially, it was for biosecurity reasons with the boundaries planted to natives but then it continued as stock shelter, for biodiversity benefits, to reinstate riparian zones for erosion and water quality control and, finally, for harvesting timber as an additional income stream.

Around 10 per cent of Knewleave is now planted to trees, with recent species selected for their increased ability to sequester carbon.

Ms Conroy and Mr Nicholson have used the FullCAM model - a calculation tool for modelling Australia's greenhouse gas emissions from the land sector - to put a figure on how much carbon their trees are sequestering, which along with their other measurements gives a good indication of their property's carbon balance.

At most points of their journey they have been carbon neutral or positive but Ms Conroy says given globally accepted methane measurements are forever changing, it's hard to make that claim permanently.

She says carbon was always part of the discussion: "Thirty years ago when we started putting trees in, dad said the carbon sequestration benefits of this will one day have a monetary value.

"But it was probably around 12 years ago when Cam became involved in the federal government's Carbon Outreach program, and then especially when Meat & Livestock Australia announced [in 2017 it's goal to be carbon neutral by 2030], that we started to look at our numbers and our carbon intensity with the view to maintaining a carbon neutral status," she said.

"Our detailed farm records meant we could go back through our data and analyse our carbon position from 2006-07 onwards.

"Our soil testing initially was 10cm deep and was designed to give us a picture of things like acidity, phosphorous, sulphur, potassium - the parameters that affect productivity.

"We've now tested down to a metre to build a better carbon picture into our data bank."

Their soil carbon has lifted to just over 3 per cent over the decades they've been testing, providing an improved soil structure and water retention that has contributed to productivity.

"Of course, the thing about increasing productivity is that is can potentially result in more methane emissions," Mrs Conroy said.

"So our focus has been on being the most efficient for the amount of methane we emit."

Today, the operation has an emissions intensity well below industry benchmarks.

Earning ACCUs, or Australian Carbon Credit Units, hasn't crossed their minds because it involves implementing a new practice, whereas Knewleave is well established on the its own carbon neutrality path.

While there has been criticism of the ACCU program on the grounds it disadvantages the trailblazers in this space, Ms Conroy said: "We see no disadvantage. We've absolutely been advantaged by what we've done because we've been more productive and profitable as a result for all those years."

"The last thing I would do is commit to selling our carbon when it is likely to be so valuable within our business - we are considering using the federal government's Climate Active program to independently certify our carbon position.

"We are in the business of livestock. Carbon comes with you along the way. Carbon should be a key part of every productive farm.

"Carbon accounting will become mainstream for farmers. Start by getting together your baseline figures and understanding what your emissions are."