Getting down and dirty: soil carbon and the future of farming

Whatever the truth about the soil carbon debate, we have every reason to attend to the health of our rural sector. [6 September 2011 | Peter Boyer]

Avoiding synthetic fertilisers and focusing on soil’s natural structures and water-carbon flows are the essential ingredients of long-term farm productivity, says Dr Christine Jones. PHOTO ABE COLLINS

Avoiding synthetic fertilisers and focusing on soil’s natural structures and water-carbon flows are the essential ingredients of long-term farm productivity, says Dr Christine Jones. PHOTO ABE COLLINS

I had a transformative experience last week from some unexpected sources. Farmers and soil scientists aren’t the first people most of us would look to for insights into our future, but perhaps they should be. After all, the subject of their labours is what keeps us alive.

We’d all starve if the world relied on people like me for food. Luckily others have the knack. Despite our old and relatively infertile soils, our farmers have found ways of getting enough out of the land to make this country a major global food exporter.

Dr Christine Jones is an Armidale (NSW) soil scientist who has built a career on studying soil’s natural capacity to regenerate itself by means of functioning communities of plants, root fungus and microbes.

Jones has campaigned long and hard for greater awareness about the need to regenerate our topsoil and our capacity to grow mineral-rich plants by attending to water and energy flows and greater rates of carbon sequestration in the soil.

For decades, farmers have been told that Australian soils need extra nitrogen and phosphorous to improve fertility. According to Jones, “nothing could be further from the truth”. As she sees it, synthetic fertilisers slowly degrade the soil by destroying root fungi essential to plant growth.

“Adding synthetic nitrogen inhibits the microbial associations that would otherwise enable plants to access some of the 78,000 tonnes of nitrogen that sit above every hectare of land, available free of charge, and adding phosphorous is even worse”.

With soil carbon storage looming as a major issue in the debate over how we might contain our carbon emissions, Jones sees actions to improve our soil management as a double bonus. A fully-functioning natural soil grows more and better food, but like a functioning natural forest it also is the best bet for maximising carbon storage.

In a 2008 paper on soil carbon, she claimed that “a soil carbon improvement of only 0.5 per cent in the top 30 cm of 2 per cent of Australia’s estimated 445 million hectares of agricultural land would safely and permanently sequester the entire nation’s annual emissions of carbon dioxide”.

This is a big call. Early this year Greg Hunt, Liberal climate spokesperson, cited Jones as an authority for his party’s policy to use soil carbon sequestration as the principal means of cutting carbon emissions by the targeted 5 per cent by 2020.

CSIRO scientists have weighed in to the debate, asserting in a 2009 research paper that to sequester the targeted amount of carbon dioxide would require at least 75 million hectares — more than eight times Jones’s estimate — and possibly as much as 500 million hectares.

They have also questioned Jones’s claim that synthetic fertilisers inhibit carbon sequestration in the soil. Increasing plants’ growth rate, they say, adds to the take-up of atmospheric carbon.

In response, Jones says that CSIRO soil science is coloured by its long association with commercial manufacturers of synthetic fertilisers, causing it to support their widespread use and to reject any claim that they damage our topsoils. It seems this debate has a way to go yet.

The Gillard government’s recently-legislated “Carbon Farming Initiative” is also putting great store in improving farming practices, though it doesn’t rely on soil sequestration in its 2020 target.

Under the government’s proposed carbon pricing scheme, to be debated by parliament in its next session, farming interests would be exempt from a carbon price on their fuel use, and would benefit from over $1.7 billion of carbon revenues to be invested in rural land management.

Whatever science might determine about soil carbon, both sides of politics are absolutely right to think they should support food producers, their communities and the land they care for. All are suffering from global economic shifts that are heedless of such things.

Last week, Christine Jones referred me to a telephone conference led by a Tamworth farmer named Garry McDouall, on the theme of how farmers can manage an escalating pace of change.

I half-expected a homily on why this practice is better than that. Instead I got a rousing discussion of the big global issues, the difficulties farmers face because of changing physical and economic parameters, and why they should feel confident they can meet and overcome these challenges.

Farmers should tackle the future with a positive mindset, says McDouall. They should set their sights above merely marking time — “regeneration should be the theme, not sustainability” — ensuring that the land’s natural processes work to maximum effectiveness. But outside recognition and support was also needed.

McDouall pointed to Murrumbidgee farmers who left their oranges on the trees because they were offered $150 a tonne — less than the cost of production — for fruit that retailed at $4000 a tonne; and to country post offices in failing rural high streets handling tonnes of parcels a day for local internet shoppers.

The problems of farmers and rural communities belong to everyone. This is a debate we all need to be part of.

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