Sir Rob Fenwick: Grounds for environmental concerns

New Zealand soil is mostly the fragile product of giant forests destroyed a century or so ago takes about three centuriesto regenerate about 10mm. Photo / PeopleImages.com

Opinion

COMMENT:

While the entrails of the Government's well-being framework remain a mystery to most, the idea of measuring and protecting our environmental assets, as we do our economic assets, makes sense.

This is especially so in New Zealand where the economy is almost totally reliant on healthy, productive biological systems, driving 80 per cent of our earnings and supporting thousands of jobs and families.

This is what Treasury boffins mean when they talk about the "pillar of natural capital". We better get used to the language because the incorporation of natural capital in their budgets will get increasingly coherent for future governments.

Let's not forget Sir Bill English and his Treasury officials were grappling with this concept before the last election.

There are five basic components of natural capital: Our soils and the numerous things that grow in them; our freshwater; our unique biodiversity; our marine environment and our climate.

They're all inter-linked and, according to Ministry for the Environment's recent Environment Aotearoa Report, all five domains are declining - in some cases, steeply.

Freshwater is the issue New Zealanders worry most about according to opinion polls.

Climate change, now tagged an emergency, has become a chilling reality with more extreme weather and the challenge of achieving the global temperature target of +1.5C is looking very difficult.

Our coastal marine environment suffocates under a blanket of sediment resulting from poor land use decisions and the country battles invasive predators in the war to save our biodiversity.

So what about the state of our soils? The fragile crust is often less than a metre thick, playing host to an extraordinarily complex ecosystem of tiny plants, animals and microbes, and supports not only everything we eat but also the forests and grasslands that make New Zealand's landscapes so marvelled at by millions of tourists.

We need this rich organic matter to somehow get back onto the soils of commercial growers and farmers as nature intended. Some of us do this by composting our vege gardens but is this possible on a large municipal scale?

Sir Rob Fenwick

Well, our soils aren't doing very well at all, due mainly to erosion worsened by climate change induced weather events and compaction by intensive agriculture and horticulture.

Scientists reckon we lose about 300 million tonnes of soil every year into the ocean. That's an area the size of Waiheke Island a metre deep washing into the sea, lost forever.

As well as the obvious observation that productive soil is vital for the livelihoods of farmers and growers, this massive loss of topsoil is chronically serious for other reasons.

New Zealand soil is mostly the fragile product of giant forests destroyed a century or so ago. It's highly organic and it takes nature about three centuries to rebuild 10mm.

Can we accelerate the re-introduction of organic matter into soil to keep it healthy? It all sounds like a rural problem that townies can't do much about. Wrong.

Urbanites can make a big difference to improving soils both by what we eat and by what we do with our waste.

Overstocking of cows on some farmland is not good for soils. Soil compaction or pugging during winter by heavy animals can damage soil structure and lead to erosion on steep land, hence the pressure to make better land use decisions to farm the right animals on the right land. It's another good reason to cut back to steak once a week. It's also why we must frantically plant new permanent forests.

But there's a bigger story about how cities can and should play their part to restore the land that feeds them.

Sir Rob Fenwick. Photo / Supplied

About a quarter of the waste Aucklanders create is food waste from homes, supermarkets and restaurants that is currently thrown into landfills. This is the stuff by the way that produces methane in landfills, so if they're not well engineered, it increases our carbon emissions.

More importantly, we need this rich organic matter to somehow get back onto the soils of commercial growers and farmers as nature intended. Some of us do this by composting our vege gardens but most don't and so is this possible on a large municipal scale?

In Christchurch, every home has a large green bin for food and garden waste which is collected with recyclables and general waste bins. The organic waste is taken to an industrial scale composting plant capable of converting 80,000 tonnes of waste a year into high quality compost.

All over Canterbury farmers and growers are buying the city's compost to add back organic matter to soil making them less reliant on chemical fertilisers.

What an asset this would be for Auckland. As we grapple with the complexities of protecting declining natural capital, a facility that enables all city folk to participate by diverting food waste from landfills into compost and enhancing production of their food couldn't make more sense.

A regional composting plant has been in Auckland Council's annual plan for as long as I can remember but, for incomprehensible reasons, has been delayed year after year. Surely its time has come?

• Sir Rob Fenwick co-founded Living Earth, NZ's municipal composting business and is co-founder of Aotearoa Circle, a group of senior public and private sector heads committed to reversing the decline of the country's natural capital