150,000 ways to hold on to the land

By SIMON COLLINS science reporter

Colin Hull has planted his farm with tyres in a desperate effort to prevent it from disappearing under advancing sand.

In 12 years, he has laid more than 150,000 tyres on tongues of sand which blow in "like a cancer" from exposed coastal clifftops on the Awhitu Peninsula, southwest of Auckland.

This year's bitter El Nino winds have expanded the sand area by half. Mr Hull, who is now past 60, says: "The problem is just getting beyond me."

The Waiuku farmer's nightmare is an example of this country's rapidly vanishing coastline. His land is being buried under sand.

Further inland, soil is washing away into the sea at 10 times the average world rate and global warming is raising sea levels, making the problem worse.

Most of the North Island coastline is classified as "erosional". And about 10 per cent of the country suffers from "severe to extreme" erosion, mostly in the mountains or in unstable hill country.

On the East Coast, serious slips have affected almost a quarter of the land cleared of forest for pasture. Carbon, which helps plants to grow, is disappearing from the soil in the market gardens of South Auckland and in croplands in the Waikato and Manawatu.

A Ministry for the Environment report warns that it takes up to four centuries for nature to build a centimetre of topsoil and up to 12,000 years to develop sufficient soil to form productive land.

Yet a single storm can wipe out soil at the rate of up to 100 tonnes per hectare.

The problem has serious implications for an economy that derives so much export income from the land.

David Craig of the Awhitu landcare group said other farmers further up the peninsula had lost around a quarter of their land, and many could be forced off in the next few years.

Mr Hull's nightmare began just after he turned 50. The day after he took his $20,000 redundancy cheque from the Glenbrook steel mill in 1991, the El Nino winds began. He estimates almost a quarter of his 225ha is now a desert.

His solution started in 1995. For a while, he took every tyre that South Pacific Tyres rejected - about 3000 a week, delivered on Thursday mornings.

Up on the steepest sandblows, his children worked in relays to roll tyres a short distance at a time. "If you let them roll too far towards you, they would get a speed up and break your knees," he said.

Auckland Regional Council land management officer Tony Thompson said Mr Hull would have been better off planting marram grass to stop the erosion.

He said 5 to 10 per cent of Mr Hull's farm should be retired from farming permanently, and another 10 per cent temporarily while the marram grass stabilised the land. But the rest of the land could still be saved.

"The sandblows are potentially productive," he said. "If Colin had put half the effort into putting marram grass in instead of tyres, he would have made more progress years ago."

A Herald series: Our eroding nation - a six-part investigation into the state of New Zealand's land - begins today.

Herald feature: Environment