The development of agriculture during the past centuries and particularly in last decades has entailed depletion of soil carbon stocks created through long-term evolution. Agricultural soils are among the planet's largest reservoirs of carbon and hold potential for expanded carbon sequestration (CS), and thus provide a prospective way of mitigating the increasing atmospheric concentration of CO2. Soils can sequester around 20 Pg C in 25 years, more than 10 % of the anthropogenic emissions. At the same time, this process provides other important benefits for soil, crop and environment quality, prevention of erosion and desertification and for the enhancement of bio-diversity.

The UN Convention to Combat Desertification (UNCCD) is concerned that extensive areas of formerly productive land, in the arid and semi arid regions in particular, have been rendered unsuitable for crop production due to ongoing land degradation. Land degradation does not only reduce crop yields but often reduces the carbon content of agro-ecosystems, which is of concern to the UN Framework Convention on Climate Change (UNFCC).

The UN Convention on Biodiversity (UNCBD) is concerned that biodiversity and conditions conducive for biodiversity are being reduced in agro-ecosystems due to the very same processes. It is therefore important to identify what important synergies can be found between these three UN conventions; UNFCC, UNCCD and UNCBD. In other words, can we find activities that will contribute to fulfilling all three conventions?

The principal benefits of sustainable soil carbon management at various spatial scales are summarized below:

Carbon sequestration holds the promise of win-win options and introducing new benefits into dryland farming communities. Some of these benefits concern the farmer and the soil quality, others the protection of the soil and water resources and the environment. Most important are the economics benefits.

Within the context of the Kyoto Protocol and subsequent COP discussions, a number of features make CS on agricultural and forestry lands an attractive strategy for mitigating increases in atmospheric concentrations of greenhouse gases.

The UN Convention to Combat Desertification (UNCCD) is concerned that extensive areas of formerly productive land, in the arid and semi arid regions in particular, have been rendered unsuitable for crop production due to ongoing land degradation. Land degradation does not only reduce crop yields but often reduces the carbon content of agro-ecosystems, which is of concern to the UN Framework Convention on Climate Change (UNFCC).

The UN Convention on Biodiversity (UNCBD) is concerned that biodiversity and conditions conducive for biodiversity are being reduced in agro-ecosystems due to the very same processes. It is therefore important to identify what important synergies can be found between these three UN conventions; UNFCC, UNCCD and UNCBD. In other words, can we find activities (“win-win”) that will contribute to fulfilling all three conventions?

The Clean Development Mechanism (CDM) of the Kyoto Protocol (Article 12) is one of several flexible mechanisms created to facilitate parties of the convention to cooperate with each other to reduce emissions of CO2. The CDM is the only mechanism specifically designed for developing countries. Recent post Kyoto agreements consider soil sinks in countries, recognizing the substantial potential of agricultural, grassland and forest soils to sequester carbon and the need for provision of national credits for the expansion of carbon sinks in agricultural soils.

A number of agricultural practices are known to stimulate the accumulation of additional soil carbon in addition to improving soil fertility and land productivity, as well as having positive environmental effects. Their role in the management of carbon is likely to increase as we learn more about the characteristics of these new approaches, such as the adoption of conservation tillage and the careful management of soil organic matter.

A quantification of all these effects is required to better evaluate the contributions of soil carbon sequestration to farmer’s welfare and environmental improvement. Some priorities can be defined for degraded lands with adapted measures for croplands, pastures and agro-forestry. Development of conservation agriculture will be the key.

Role of FAO

In order to contribute to a better understanding of potential carbon sequestration by soils the Land and Plant Nutrition Management Service (AGLL) of FAO is engaged in investigations on agricultural soils as carbon sinks under land use change in different conditions and land management practices. This is part of its programme on the integrated planning and management of land resources to address the urgent need to reverse land degradation due to deforestation and inadequate land use/management in the tropics and sub-tropics. The objective is to provide sound factual information on soil carbon sequestration potential, in particular, in arid and semi-arid areas for several purposes, including:

1. the promotion of improved land use systems and land management practices which provide economic gains and environmental benefits, greater agro-biodiversity, improved conservation and environmental management and increased carbon sequestration.
2. assist the emerging debates on sustainable land use and climate change mitigation.
3. help CDM, GEF and other funding agencies, planners and administrators in their decisions to undertake research, development and investment programmes in the agricultural/rural land use sector aiming at improving land management, checking land degradation and deforestation.
4. contribute to the development of regional and national programmes linking the Convention on Climate Change (UNFCC) and the Kyoto Protocol, the Convention to Combat Desertification (UNCCD) and the Convention on Biodiversity (UNCBD), focusing on synergies among the three Conventions.

FAO AGLL is also playing an important role in the validation and promotion of concepts. It is helping to measure, monitor, model, train and then organise networks in order to assist small farmers to develop and adapt practical solutions.