Landcare Australia turns 30 this year, but one of its original members fears its impact will wane as volunteers retire or cut back their involvement.

The national Landcare movement began in 1989, when the Hawke government committed $320 million to encourage productive and sustainable land management.

Since then, local communities have set up more than 5,400 Landcare and Coastcare groups across the country.

Among the original volunteers is 73-year-old Tasmanian land carer Graeme Stevenson, a Landcare living legend and finalist for the prestigious national Landcare prize, the Bob Hawke award.

Mr Stevenson is an expert in earthworms and dung beetles. ( Supplied: Graeme Stevenson )

"The big challenge Landcare has on its hands is to get more young people involved," he said.

"We have tried at primary age and they are rapt, but we need to get them at high school age and that's the catch, and I'm not too sure how we go about it."

Landcare Tasmania's CEO Rod Knight said Mr Stevenson's passion for land management was infectious.

"People like Graeme have an impact far bigger than one person normally should," he said.

"He infects other people with enthusiasm to take on better land management and he gives them knowledge and confidence to carry it out."

Mr Stevenson said his spirits were lifted when he saw young people march for climate change earlier this year.

"Oh yes, that's showing us oldies how to go about it," he said.

Teaching kids the art of 'poo-ology'

An agronomist and soil classifier, Mr Stevenson has been a member of four Landcare groups, Coastcare and Waterwatch in north-west Tasmania, where he has planted trees, pulled weeds, and helped fence off creeks and penguin colonies.

His 30 years of labour are evident throughout the farming landscape, but his special skill is filling out grant application forms.

"All the study I have done just gave me a hand with words, and I was able to help farmers who felt put off by forms," he said.

Mr Stevenson as his eccentric alter-ego Dr Spluttergrunt teaches a class of primary school children. ( ABC: Pip Courtney )

It's estimated his fluency in bureaucracy has brought more than 1 million in grants to the region.

A recent cancer diagnosis has forced Mr Stevenson to scale back his volunteer work, but it hasn't stopped his alter-ego, soil expert Dr Spluttergrunt, visiting Tasmanian primary schools.

He tells students he's a qualified "poo-ologist" and encourages them to laugh, learn and say the word 'poo' a lot.

"The kids seem to suck it all up, they're not yet at that stage where they pretend they're adults and ignore good advice," he said.

"The kiddies just take it in like a big sponge."

A dung beetle expert, Mr Stevenson also educates about the environments most suited to the soil-regenerating insects.

Soil health, dung beetles and grant applications are all part of Mr Stevenson's repertoire. ( Supplied: Graeme Stevenson )

"They like fresh horse poo, the fresher the better," he said.

"They like cow poo that's two to three days old and they'll eat dog poo and cat poo, but sheep poo is too hard."

Primary school teacher Sherrie Jaffray said Mr Stevenson's enthusiasm and knowledge was highly valued.

"His wealth of knowledge is amazing and he can communicate that knowledge to children at this level, to all levels of people," she said.

"He is very unique. We are very fortunate and blessed to have him in our region."

Mr Stevenson is known as an eccentric and often excitedly flings his arms about when describing his favourite things, people and soils as "gorgeous" or "yummy".

He's serious, however, when it comes to soil preservation.

"It's our grandchildren's inheritance, so don't abuse it," he said.

Mr Stevenson washes dung beetles with his granddaughter. ( Supplied: Graham Stevenson )

Watch this story on ABC TV's Landline this Sunday at 12:30pm or on iview.