Scientists go to ground for answers

Apr 1 2008 by Tony Henderson, The Journal

WHEN it comes to tackling climate change, the answer could, after all, lie in the soil.

A team from Newcastle University aims to score a global first by designing soils that can remove carbon from the atmosphere, permanently and cheaply.

The research is being funded by the Engineering and Physical Sciences Research Council.

The concept exploits the fact that plants, crops and trees naturally absorb atmospheric carbon dioxide during photosynthesis and then pump surplus carbon through their roots into the earth.

In most soils, much of this carbon can escape back to the atmosphere or enter groundwater.

But in soils containing calcium-bearing silicates – natural or man-made – the team believes the carbon which oozes out of a plant’s roots may react with the calcium to form the harmless mineral calcium carbonate.

The carbon then stays securely locked in the calcium carbonate, which simply remains in the soil, close to the plant’s roots, in the form of a coating on pebbles or as grains.

It opens up the prospect that bespoke soils can be designed – with added calcium silicates, or specific plants – which optimise the carbon-capture process.

The team will first look for calcium carbonate in natural soils that have developed on top of calcium-rich rocks or been exposed to concrete dust which contains man-made calcium silicates.

They will then study artificial soils made at the university from a mixture of compost and calcium-rich rock.

Finally, they will grow plants in purpose-made soils containing a high level of calcium silicates and monitor accumulation of calcium carbonate.

The research team, including civil engineers, geologists, biologists and soil scientists, is led by David Manning, Professor of Soil Science at Newcastle University.

He said: “No one has tried to design soils expressly for the purpose of removing and permanently locking up carbon. A key benefit is that combating climate change in this way promises to be cheap compared with other processes.”