We waited and, in one sense, wasted decades, scientifically establishing carbon emissions, and their effects. Now its about sequestration, on and in the ground: a different issue, yet the same

Science told us the risks of climate change. We needed it, to explain how nature works, in a way that no one can observe.

Now, it joins the race for good solutions. Where the science is disputed, as it is on soil carbon, is there time left to explain everything, paper by paper, and peer-review? And yet, there’s no time, either, to waste on crackpot theories.

On soil carbon, there seems a gulf, between what science can validate at this point, and observations on the ground, dismissed as ‘anecdotal’, but racing to establish themselves in terms that are scientifically, agriculturally, economically credible.

I don’t know who or what to believe. The anecdotes are compelling; I'm not equipped to dispute the science. And — since this seems a fractious, rumbly area — I will say from the outset that what follows is over-simplified, but I hope, without being simplistic.

It contrasts Dr Christine Jones’ findings with those of our own Jacqueline Rowarth, professor and Massey director of agriculture. It 'contrasts' them, although both Jones and Rowarth are doing the science of pastoral agriculture: this is not a simple dichotomy between one woman who showed us some nice paintings and goes out to dig in the paddock, and another with some scary graph-and-flowchart thingies. And yes, one is Kiwi, one Australian — countries with such different soil circumstances, they might inhabit different planets, making contrasts or comparisons spurious.

Jones says the Kyoto Protocol, which New Zealand hasn’t signed for soil carbon, measures the wrong thing. It applies to the top 30 cm. The most significant carbon changes, she says, happen at depth, from 40-100 cm.

Whether or not for the right reasons, then, New Zealand officials’ instinct and advice not to buy into it, on the basis that we don’t know enough about how this all works, may have been the right one. And their judgement is backed by Rowarth, too. Scientific unanimity on this, then, phew.

Jones paints a verbal picture, and shows her audience actual painted pictures, of what Australian pasture used to look like, two centuries ago when the settlers arrived: deep top soil and lush native grasses mid-summer, truly, the lucky gorgeous country. It eroded, she says, through land mismanagement, to the dust bowl we know today. Downstream, it kills rivers, from silt washing into them, and people too, perhaps: depleted Aussie soil grows depleted food.

If Australia has a lesson for New Zealand, she says, it would be: don’t copy us.

She shows us a former family farm, now split into four, among four brothers: a natural case study. One of the brothers manages his soil biologically. He re-sowed native perennial pasture grasses, and keeps the soil always covered, by ‘pasture cropping’; when he sows winter cover crops, for example, they’re drilled straight into the grass. He manages overgrazing, yet his land now supports double the number of stock of his brother’s, on the neighbouring property.

And the two places look quite different, visually, and on the hard data. Spadefuls, side by side, show different soil structures, with more topsoil on the biologically-managed property. And different soil carbon levels: up to three times more in the top layers, to 30 cm, and a PhD (“I can’t release the data, unfortunately”) in the pipeline that will show big positive changes, at 40-100 cm depth.

These are farmers managing without conventional fertiliser, using only natural applications: vermiliquid, and compost tea. Building carbon, Jones says, builds nitrogen and potassium, without external inputs.

Most importantly, though, it’s the grasses doing the work. She shows us a Western Australian desert, in five-month 40-degree summer drought. A pitiful little cover crop of grasses seems to condition the soil: it’s visible in the soil itself, and the performance of intersown crops, that perform best right on top of the stunted grass rows.

She thinks it is their roots, doing deep carbon storage. Photos of the roots of the perennial grasses, compared to annual and urea-fertilised grasses, show healthy-enough looking tops, of comparable size, but hardly any roots at all on the fertilised sample, and fewer roots on the annuals, compared to the great bearded perennial structures.

CSIRO, Australia’s national science agency, calls this all ‘anecdotal’. But it will, she says, be published and peer reviewed in short order: it will be real science, in other words.

Since Jones works on highly depleted Aussie soils, unlike New Zealand soils, it’s perhaps worth noting that another New Zealand speaker, Plant and Food Research’s Markus Duerer, presents on the results of a comparative Kiwi study — literally, on a couple of kiwifruit orchards — with similar conclusions, about carbon storage at depth, and deep root growth as the most promising method of soil carbon sequestration.

Massey’s Jacqueline Rowarth, on the other hand, tells at length how she, and her students and colleagues, have struggled to validate this science. It’s such an uncertain science, she concludes, that it isn’t feasible to count on soil-stored carbon as a feature of an emissions trading scheme, or for international carbon accounting, at this stage. It would be a risk for farmers; it could result in them being penalised.

Hers was a story about dead plants, and wildly variable results, out in the field.

She hasn’t abandoned the cause though: on the contrary, she wants to see more research, and better-funded research. Impecuniosity, and the inadequacy of Agresearch’s present funding grant, was a refrain of her talk.

Rowarth is a scientist with enormous stock in the farming community, as someone who understands farmers’ issues and champions their cause. She has said publicly that agriculture needs excellent science; they are a natural partnership.

Her views count. Dubbed the “inspirational” Jacqueline Rowarth by Federated Farmers, she was their ‘agricultural personality of the year’ in 2009. She told Rebecca McFie recently that farmers should be paid, to introduce good, environmentally-friendly technologies — subsidised, in other words, as they are in Europe. She challenges organics’ productivity, and says intensification is our opportunity, given the world’s scarce arable land.

She and Christine Jones are doing their science in quite different circumstances. But a question in my mind, as I listened to them both, was whether there’s a different mindset at work here too: a factor that surely even a scientist must take into account, in assessing the validity of the results, and finding out what works.

I wanted to know what, in practice, Rowarth isn’t doing that Jones is, and vice versa.

If something is observed in the field, and a scientist can’t validate it, or can’t validate it quickly enough, does it mean it isn’t true? I try things in my garden, and keep doing what my eyes tell me is working, and will give me a firmer foothold on this planet; I don’t always need to know why or how.

But that’s not how the international Kyoto accounting system works, of course, or science, or the many vested, and cynical, interests. And that makes me fear for us all, knowing how long it took, to establish climate change, and that we don’t have the same time left to find and implement its solutions.