Clive Blazey (CB) interviews organic leader Tim Marshall (TM)

CB: As a leader in the organic movement, where does climate change fit, in your hierarchy of priorities?
TM: When it comes to choosing the food I buy, organic is actually my fourth choice. I would choose local and seasonal products, particularly from farmer's markets, ahead of organically certified products, particularly if those products have travelled long distances. I feel that our diet needs a diversity of foods, all of which I would consider ahead of organically grown food.

Climate change is the issue and organics is part of the solution. Organics is an integral part of the solution to climate change, but it is a means to an end, not the end itself.

CB: What is your solution to the issue of climate change?
TM: Most of the responses to climate change being considered will not stop the global mean temperature rising to critical levels. If we stopped emitting greenhouse gases today, there is already enough CO² in the atmosphere to cause climate chaos. It is the 'legacy load' of 200 years of industrial emissions.
The Prime Minister's favoured options of 'clean coal' and nuclear power cannot capture existing CO² in the atmosphere, they can only prevent future emissions.
Forests can absorb legacy load CO², but there is not enough space on Earth to plant enough trees to absorb the world's emissions. We would need seven planets.

Soil is the largest carbon sink over which we have control. It holds twice as much carbon as the atmosphere, and twice as much as all the vegetation on Earth, including forests (see diagram). Sixty percent of the Earth's surface is used for agriculture. This soil can remove more CO² from the atmosphere faster and more economically than trees or any other method.

Simple changes in land management can immediately start the process of CO² removal. These changes can be made immediately if farmers are paid carbon credits ($25 per tonne of carbon emission on European Climate Exchange). A 1% increase of soil carbon, in 10% of Australia's agricultural soils, would remove 10 year's worth of legacy load from the nation's emissions.

CB: Why hasn't the organic movement got government support like the tree plantation industry?
TM: The organics movement lacks a figurehead, and unity within the alternative approaches to organics. Without a concentrated focus there are no funds. The non-renewable energy lobby of coal, fertilisers, farm chemicals and genetically modified seeds has the ear of government. Organics is a system that has to fight defined products that are vastly more powerful.

CB: Can you explain why soils are a better carbon sink than trees?
TM: Soil carbon is more stable. Trees can be burnt and trees drop leaves so they shed carbon during Winter or droughts. There is more carbon below ground than above it, particularly in the roots of trees.
The most efficient method of accumulating carbon in soils must be by direct decomposition of plant material. Soil carbon is created by bugs and microbes living and dying as a consequence of the vigorous root action in the soil. The rotting remnants of organic matter feed the microbes that produce soil carbon.
Plantations, particularly monocultures that replace natural forest, destroy diversity. Yet the forest lobby has influence and tax deductibility, not offered to organic growers.

CB: What organic soil carbon levels should we be striving for?
TM: Soil carbon levels are highest where optimum growing conditions exist. Except in the tropics, where biomass is concentrated in the vegetation, there is actually more carbon under the ground than above.
In temperate regions, a 5% level is normal, whilst dry grassland is approximately 3%. Australia's soils have fallen to about 1.5%, as a consequence of poor management.

Ploughing disturbs microbes, dries out the soil, and releases CO² into the atmosphere. During a wheat cropping cycle, land is exposed, heated and dried, suppressing biological activity. If farmers went back to a grazing/cereal crop rotation, as organic wheat farmers do, organic levels will rise, as manure and grass provide good conditions for microbes below the ground.

Gardeners who compost and mulch their plants usually have organic levels of 5-10%. Which is as much as is needed to maintain sustainable, fertile oils. Organic soils are not just the solution to climate change, they also hold more water, solving our water shortages.