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Title: Supporting Evidence for Greenhouse Gas Mitigation in Agriculture

item Dumanksi, Julian
item Desjardins, R
item Lal, R
item De Freitas, Pedro
item Landers, John
item Gerber, Pierre
item Steinfeld, Henning
item Verchot, Louis
item Schuman, Gerald
item Derner, Justin

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/9/2009
Publication Date: 7/2/2010
Citation: Dumanksi, J., Desjardins, R.L., Lal, R., De Freitas, P.L., Landers, J.N., Gerber, P., Steinfeld, H., Verchot, L., Schuman, G.E., Derner, J.D. 2010. Supporting Evidence for Greenhouse Gas Mitigation in Agriculture. In: Stigter, K. (ed.), Applied Agrometeorology. Springer, Heidelberg, Germany. pp 1101. Book Chapter.

Interpretive Summary:

Technical Abstract: INTRODUCTION There are many opinions on the potentials for GHG mitigation in agriculture, but it is not always clear which among these are the most reliable and useful. The issues are complex, and the opinions as many and varied as those who have been brave enough to put their ideas forward. This collection of case studies and supporting documentation, prepared by world authorities in their field, is an attempt to move us towards some resolution of these complex questions. The options discussed are farming systems with the highest potentials for GHG mitigation in agriculture. These include agroforestry, rangeland management, zero tillage, and livestock production. Undoubtedly, other options may provide benefits in local situations, but recent evidence indicates that these farming systems provide the best opportunities. Recommendations are also provided on procedural and institutional changes needed to enable farmers to capitalize on the opportunities in the carbon market, particularly for farmers in developing countries. The case studies and documentation are discussed below: GHG Mitigation in Agroforestry Systems (Prepared by Louis Verchot, Principle Scientist, CIFOR) Agroforestry systems in the humid tropics include various types of tree-based production systems. Research in these areas (Palm et al. 2002) showed that conversion of primary tropical forests to cropland or grassland resulted in the loss of about 310 Mg C ha-1, with managed or logged forests having only about half the C stocks of primary forests. Agroforestry systems contained 50 to 75 Mg C ha-1 compared to row crop systems with < 10 Mg C ha-1. These results show that converting row crops or pastures to agroforestry systems can greatly enhance the C stored in above and below ground biomass. Agroforestry also compares well with other land-uses with respect to other GHGs. In Sumatra, a jungle rubber system had lower N2O emissions than a primary forest, but also lower CH4 uptake (Tsuruta et al., 2000). However, agroforestry systems such as multi-story coffee with a leguminous tree shade canopy had N2O emissions five times higher than open-grown coffee and about half the CH4 uptake (Verchot et al., 2007). In Peru, agroforestry systems (multistrata coffee and a peach palm plantation) with leguminous cover crops had lower N2O emissions than both intensive and low-input agriculture and similar emissions to a nearby secondary forest (Palm et al., 2002). Soil uptake of CH4 was similar to other land-use systems, with the exception of intensive agriculture site, which became a net source to the atmosphere. Agroforestry also has an important carbon sequestration role to play in the sub-humid tropics. Improved tree-based fallow rotations between cereal crops and tree-legume fallows have high potential to sequester C in both the aboveground biomass and the soil. Belowground C storage in these systems represents the potential for long-term C storage, as long as trees remain in the rotation, but the storage capacity is largely dependent upon soil texture and total rainfall. Coppicing fallows are newer, but follow similar trends. While these systems are cut frequently, the average aboveground carbon stocks exceed stocks in degraded land, cropland or pastures. Nitrous oxide emissions following the leguminous tree fallows was found to be almost 10 times that of unfertilized maize (Chikowo et al., 2003) but these levels were still extremely low in comparison to the amount of C stored. Restoration of degraded land using improved tree fallows has the potential not only to sequester significant amounts of C from the atmosphere, it also offers opportunities for improving rural livelihoods by turning unproductive land into productive land that can produce food, wood and other tree products, and generate income. Typically, there are tradeoffs between carbon stored and on-far