Soil the Key to Carbon Capture?

To help mitigate climate change, it is possible to capture carbon in soil to avoid its release into the atmosphere. Breakdown of organic matter by organisms in the soil bacteria, releases carbon and incorporates it into the soil as soil organic matter (SOM). A new review has explored different EU strategies for capturing carbon in soil.

As part of the Kyoto1 protocol, the 15 member states that made up the EU in 1997 are committed to reducing CO2- equivalent (CO2-eq)2 emissions by 8 per cent by 2008-2012. The first European Climate Change Programme (ECCP I)3 has identified new methods to achieve this goal and the role soil plays in capturing carbon has been investigated.

An ECCP report4 estimated that up to 60-70 million tonnes of CO2-eq per year could be captured in agricultural soils. Carbon can be trapped in soil, by the activity of bacteria, fungi and earthworms. They convert organic matter into a substance known as humus, which remains as part of the soil and prevents carbon release as CO2. One way to get more carbon into soils is by spreading biodegradable organic wastes such as crop residues, farmyard manure, compost and sewage sludge onto agricultural land. Combining soil and waste management in this way directs carbon to the soil where it can be captured and has the added benefit of reducing the amount of waste that goes to landfill. Estimates of the contribution this method could make to carbon capture range from 2-20 million tonnes of CO2-eq per year, due to regional differences in soil, management practices and climatic conditions.

A crucial factor is the quality of the waste that is spread onto the land. An initiative under the EU Waste Framework directive5 aims to define quality standards for biodegradable waste. In addition, the Joint Research Centre is developing guidelines, in collaboration with the DG Environment, to develop a Life Cycle Thinking approach to waste management. This approach examines a product or a service and estimates the total environmental impact of its extraction, processing, manufacture, waste management, recycling and final disposal. Methods to enhance carbon capture in agricultural soils and forests not only combat climate change, but also enhance soil quality. This has an impact on nature and biodiversity protection, water quality, food safety and in turn, human health. Therefore, carbon capture is still a key focus for the ECCP, which entered into its second programme in 2005.

1 Kyoto agreement http://unfccc.int/kyoto_protocol/items/2830.php

2 The amount of carbon dioxide that would give the same warming effect as the effect of the greenhouse gas or greenhouse gases being emitted.

3 http://ec.europa.eu/environment/climat/eccp.htm Launched June 2000.

4EECP I 2003 report Sinks Related to Agricultural Soils http://ec.europa.eu/environment/climat/pdf/execsummary_agricsoils.pdf

5The Waste Framework Directive has specific directives related to biodegradable waste: http://ec.europa.eu/environment/waste/compost/index.htm

6 Institute for Environment and Sustainability http://ies.jrc.cec.eu.int/ 7 http://lca.jrc.ec.europa.eu/lcainfohub/lcathinking.vm

Source: Marmo, L. (2008). EU strategies and policies on soil and waste management to offset greenhouse gas emissions. Waste Management. 28: 685-689. Contact: [email protected]