As in many other international organizations, national governments and intergovernmental bodies, climate-change issues are high on the FAO agenda. FAO is an active partner in the international conventions on climate change, whereby FAO’s mandate covers the role of agriculture in mitigating climate change.
FAO is concerned with the effect of agriculture on climate change, the impact of climate change on agriculture and with the role that agriculture can play in mitigating climate change. Historically, land-use conversion and soil cultivation have been an important source of greenhouse gases (GHGs) to the atmosphere. It is estimated that they are responsible for about one-third of GHG emissions. However, improved agricultural practices can help mitigate climate change by reducing emissions from agriculture and other sources and by storing carbon in plant biomass and soils.
The work of FAO aims to identify, develop and promote cultural practices that reduce agricultural emissions and sequester carbon while helping to improve the livelihoods of farmers, especially in developing countries, through increased production and additional incomes from carbon credits under the mechanisms that have emerged since the Kyoto Protocol.
There have been few studies on the potential of carbon sequestration (CS) under local farming conditions in rural dryland communities in developing countries. This report aims to fill this gap in knowledge. The report evaluates specific options for landmanagement practices by analysing some case studies carried out in several distinctive dryland areas of the world. The ultimate goal is to facilitate the dissemination of such practices in soil CS programmes in similar agro-ecological environments in other countries to improve food security and rural livelihoods.
The case studies presented here assess the effect of different management practices on soil carbon stocks in various dryland ecosystems. The effect of climate and/or land-use change can be predicted only through the use of accurate dynamic models. Given the difficulty of measuring changes in soil carbon stocks, modelling is a useful tool and it has been used as an effective methodology for analysing and predicting the effect of landmanagement practices on soil carbon stocks. A number of process-based models have been developed in the last two decades. The CENTURY 4.0 model was used for these case studies. Data from distinctly different dryland systems in Argentina, India, Kenya, Nigeria, Senegal and the Sudan were used in the investigations, which were carried out by the University of Essex (the United Kingdom) and Lund University (Sweden).
Some of the results predict that soil carbon can be restored to precultivation levels, and in certain circumstances to above them. The true “native soil carbon level” is often difficult to establish in systems where agricultural activity has been present for at centuries or millennia such as in Kenya and Nigeria. To achieve quantities of soil carbon in excess of the “natural level” implies that the agricultural system has a greater productivity than the native system, assuming that carbon is not being imported. The scenarios that predict the highest CS rates are often associated with the introduction of trees. The inputs of carbon from trees are more resistant to decomposition than those from herbaceous crops and consequently can cause marked increases in the level of soil carbon. The highest annual rates of sequestration (0.1 - 0.25 tonnes/ha) occur where zero-tillage systems also include cultivation of green manures and additions of farmyard manure. The use of inorganic fertilizers alone was generally inefficient in providing the necessary nutrients for increasing CS. The effect of inorganic fertilizers on CS is enhanced considerably by including cover crops in the rotation cycle. Cover crops enhance soil biodiversity, which is known to increase CS. The results of the case studies conform to rates of soil CS obtained under various land-management regimes in drylands as reported in literature sources.
There are vast areas of dryland ecosystems in the world, many in developing countries, where improvements in farming systems increase carbon stocks in soils, as shown in the case studies presented here.
While CS is not a priority in poor countries, land-management options that increase CS, enhance plant production, and prevent erosion and desertification are of major interest in these regions.
Investments in CS in drylands, as less favoured areas, are needed because they are home to large numbers of poor people and because they are the custodians of globally important environmental resources at risk of degradation or depletion.
Investments in improved land management leading to increased soil fertility and CS can also be justified in many cases because they can be a win - win situation with higher agronomic productivity and contribute to national economic growth, food security and biodiversity conservation.
Enhancing CS in degraded drylands could have direct environmental, economic and social benefits for local people. It would increase farmers’ benefits and help mitigate global warming, at least in the coming few decades until other alternative energy sources are developed. Therefore, initiatives that sequester carbon are among the main priorities of FAO.
While a purely carbon-market approach is unlikely to be applicable to small-scale farming systems in developing countries, a multilateral approach for mobilizing resources under existing mechanisms is required. The Global Mechanism of the Convention to Combat Desertification (CCD) of the United Nations (UN) promotes such a multilateral path to increasing the effectiveness and efficiency of existing financial resources and to exploring new and additional funding mechanisms for the implementation of the convention. Specific emphasis is given to small-scale farming systems in dryland areas of the developing countries. Multilateral approaches include sources to combat climate change with desertification funds, links with sustainable livelihoods, and provision of visible benefits to local people, mobilizing resources also from the private sector. Several UN conventions (the CCD, the Climate Change Convention, the Convention on Biological Diversity and the Kyoto Protocol) all share a common goal: the proper management of soils to increase soil carbon. There are opportunities for bilateral partnerships with industrial-country institutions to initiate soil CS projects involving local communities that are also linked to global networks on CS. FAO believes that more effort should be put into exploring and exploiting these opportunities.
