Tuesday, February 26, 2008

Composting to fight climate change?

From EurekaAlert!
Applying organic fertilizers, such as those resulting from composting, to agricultural land could increase the amount of carbon stored in these soils and contribute significantly to the reduction of greenhouse gas emissions, according to new research published in a special issue of Waste Management & Research (Special issue published today by SAGE).

Carbon sequestration in soil has been recognized by the Intergovernmental Panel on Climate Change and the European Commission as one of the possible measures through which greenhouse gas emissions can be mitigated.

One estimate of the potential value of this approach – which assumed that 20% of the surface of agricultural land in the EU could be used as a sink for carbon – suggested it could constitute about 8.6% of the total EU emission-reduction objective.

“An increase of just 0.15% in organic carbon in arable soils in a country like Italy would effectively imply the sequestration of the same amount of carbon within soil that is currently released into the atmosphere in a period of one year through the use of fossil fuels,” write Enzo Favoino and Dominic Hogg, authors of the paper.

The number - 0.15% - seems small, but this is deceptive - it's still an awful lot of carbon. I'd be more interested in the mechanics of how they're going to get this done...but that would probably require actually reading the journal. The press release addresses an important point

However, capitalizing on this potential climate-change mitigation measure is not a simple task. The issue is complicated by the fact that industrial farming techniques mean agriculture is actually depleting carbon from soil, thus reducing its capacity to act as a carbon sink.

but answers this by saying

According to Hogg and Favoino, this loss of carbon sink capacity is not permanent. Composting can contribute in a positive way to the twin objectives of restoring soil quality and sequestering carbon in soils. Applications of organic matter (in the form of organic fertilizers) can lead either to a build-up of soil organic carbon over time, or a reduction in the rate at which organic matter is depleted from soils. In either case, the overall quantity of organic matter in soils will be higher than using no organic fertilizer.
Let us hope it's that simple.

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