Philippa Stevenson: Land bleeding soil at shocking rate

COMMENT


Travelling 1500km of roads in the lower North Island after the region's worst storm in 40 years is a sobering experience.

A southern sojourn last week from the relatively mild Waikato winter through the stunning, snow-capped central plateau and the repeatedly storm-ravaged Manawatu, Rangitikei and Wairarapa provided an object lesson in how not to treat the land beneath our feet.

Lashing rain and gales again ripped open land still unhealed from the February storms.

Like blood and gore from a flesh wound, soil and vegetation spilled from cliffs and steep hillsides into deep ravines whose normally mild-mannered streams were angry, clay yellow torrents.

I know from experience that from the air the dirty stain of silt-laden water at the river mouths would have spread for kilometres out to sea. This time I had only to gaze along the coast at Foxton Beach to find evidence of our land's destruction: broken trees and timber strew the sand as far as the eye can see. Worse, it's a regular occurrence, say locals who keep their home fires burning with devastation's bounty.

Driving along the just reopened State Highway 4 between Wanganui and Raetihi brought the saddest moments. Wherever you venture into rugged country you witness the erosion scars - the result of hillsides turned over to short grass palatable to sheep and cattle but patently not up to the job of holding the soil in place.

Yet, high on many steep slopes were those telltale white dots - sheep - grazing in places where you and I might contemplate wearing crampons. In too many places, also, were cattle whose heavy weight on small hooves break up the earth, making it ripe for sluicing out to sea with the next rain.

The most heartening sights (besides the hardworking road repair crews who keep the road open against tremendous odds) were the hills that bore newly planted pine trees like 5 o'clock stubble on a craggy jaw.

But where farmers have not turned to forestry or sold to forestry companies, the legacy of around 20 years of subsidies designed to boost farm production, export income and all our prosperity, is still evident in the barren hills.

Twenty years after the dismantling of the subsidies that encouraged even the most unsuitable parcels of land to be cleared for livestock, the important question is why such land is still speckled with those little white dots. What price a bit of protein when our land haemorrhages soil at alarming rates?

On a national scale, we do not need such fragile land for sheep. Not when their numbers have more than halved from their peak of 70 million 22 years ago, but the meat yield from the remaining 39 million is greater than when there were 22 sheep for every one of us.

Individual farmers, of course, need their farms to make a living but now, with the emphasis switched from short-term survival to long-term sustainability, how long - and how good - a living can be made in such an environment is an issue that needs to be addressed.

We are losing our soil at the shocking pace of an estimated 200 million to 300 million tonnes each year - an erosion rate 10 times the world average because New Zealand is relatively mountainous.

We also have a large proportion of the country - about 50 per cent - in pastoral use. A tenth of our total land is classed as severely eroded, 26 per cent is at risk from soil slippage and 39 per cent is affected by water and wind erosion.

In the most slip-prone areas, erosion has increased 10-fold since human beings took up residence. We've done a lot of damage in a very short time.

Good farming practices in the right place do little harm. In most cases soils under long-term pasture have at least as good organic matter as those under native vegetation, are much less acidic than in indigenous forest and considerably more fertile than all types of forest.

But the problem of erosion worsened by poor farming practice has been recognised since the 1930s and research shows that grazing steep and fragile land costs farmers dearly.

The gains from their flatter pastures can be easily lost on their steep country.

Hillsides that are scarred by slips are visibly shocking but even more worrying is the unseen loss as the remaining soil is slowly stripped of its fertility. That reduction in fertility can occur in just two to three generations - the time it takes for grandparents to pass the farm to the grandchildren. It's a poor legacy.

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