He thought it would be easy. He ordered 25,000 eucalypts to plant this winter and paid a deposit. He sprayed off gorse and put in vehicle tracks.
To be part of the ETS the land has to be "new" forest - not forested in 1990. A Ministry for Primary Industries (MPI) staff member has inspected his 25ha, but can't officially say it's eligible for carbon credits until it is planted.
Mr Walker isn't satisfied. There's a process through the Environmental Protection Authority (EPA) that he can use to force an early decision - but it's expensive and lengthy and he doesn't want to do it.
"It's a big exercise to crack a nut."
He's hired a mapping expert, who has photographic evidence the land was cleared before 1990, and has been reverting and had gorse cleared since.
Mr Walker's Nukuhau forest has earned him more than $30,000 in carbon credits last year. He believes it could eventually earn more than his 250-cow dairy farm at Manutahi.
He wants eroding Taranaki hill country planted for carbon storage, and he'd like Forestry Minister Shane Jones to achieve the aim of planting a billion trees in the next 10 years.
But under the Climate Change Response Act MPI cannot assess a forest for registration in the ETS until it is planted, a spokesperson said.
"As such, Mr Walker cannot get an assessment of the land without planting it."
This is nonsense, he said, because nothing about the land's 1990 status is going to change between now and when it's planted.
New Zealand needs to store carbon to meet its obligations, and he said everything was against it.
"It's a bit like they've forgotten why they are doing these things and only want to interpret the rules. Are the rules right and realistic for today?"