Philippa Stevenson: Good earth is rapidly being washed away

The rock and silt that crashed through Matata, the streams and rivers that turned brown carrying good earth out to sea should be a clarion call.

Our country's wealth comes from our top 15cm of soil and we are losing it in truckloads on good days let alone during torrential downpours.

Between 200 and 300 million tonnes of soil are lost to the oceans every year - 10 times faster than the rest of the world. The economic cost has been conservatively estimated at $127 million a year.

It takes up to 400 years for a single centimetre of topsoil to form and up to 12,000 years to develop sufficient soil to form productive land.

Erosion is much faster and although vegetation returns a few years after a site has been eroded, things are never the same.

Landcare Research scientist Graham Sparling - known as Mr Soil Quality - finds it depressing that in just 150 years of intensive agriculture we have done a good job of matching the problems being reaped from thousands of years of settlement in the Northern Hemisphere.

After last week's graphic example of soil tumbling out to sea, I went back to ask him whether we were doing enough to stem the flow.

"I would like to see much more of a national structure [overseeing soil protection]," he said. "Central government has stepped back. The Ministry for the Environment seems to have washed its hands of it."

Others in the soil business have a similar lament.

Ministry of Agriculture and Forestry director general Murray Sherwin says floods highlight the issue of land management in the same way as the Waiheke Island foot and mouth scare did disease threats. It reminds us how vulnerable we are as an agriculture-dependent nation.

It also throws the spotlight on how neglected a resource soil is.

Once we had bodies solely devoted to it - the DSIR Soil Bureau, the Ministry of Works Water and Soil Division.

In recent years, all four CRIs involved with soil research - Landcare, AgResearch, HortResearch, and Crop and Food - had major funding cuts.

But last year's Manawatu floods put soil erosion back on the Ministry for the Environment's agenda, says Sue Powell, general manager working with local government.

The ministry's Flood Risk Management Review is, in part, looking at the Government's role in flood management as well as examining available soil monitoring tools.

Regional councils take responsibility for soil health regionally and that's a reasonable approach, says Sparling. But few regional councils have active erosion controls in place, he says.

Some, but not all councils, belong to an informal regional council land monitoring group. Some councils also help landowners retire land by subsidising fencing and revegetation costs.

And that is where the major responsibility for conserving soils lies - with individual landowners.

Robyn Skelton, the regional co-ordinator for the Landcare Trust, an independent, Government-funded body that helps landowners with land management, said the flooding in her region has been a traumatic example in the push for environmental responsibility.

It's a bugbear for some landowners that they get little support for their efforts to do the right thing, she said. As well, some only see the negative aspects of their actions, say, the loss of the land they've fenced off.

The longer-term benefits are little understood.

With more research available to them they would see positive spin-offs like enhanced profits, Skelton said.

The four soil research CRIs have formed the Sustainable Land Use Research Initiative to improve knowledge of soil and land management.

It's designed to give landowners, central and local government easy access to scientists with a wide knowledge of soil and land management.

It's a welcome move toward retaining and fostering soil research. Let's hope it also helps retain and foster soils.