Strategies and Economics for Greenhouse Gas Mitigation in Agriculture

Authors: DUMANSKI, JULIAN - RETIRED SOIL SCIENTIST; DESJARDINS, R - AG AND AGRI-FOOD; LAL, R - OHIO STATE UNIVERSITY; DE FREITAS, PEDRO - EMBRAPA SOILS; LANDERS, JOHN - APDC BRAZIL; GERBER, PIERRE - FAO; STEINFELD, HENNING - FAO; VERCHOT, LOUIS - CIFOR; SCHUMAN, GERALD - RETIRED SOIL SCIENTIST; Derner, Justin

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/9/2009
Publication Date: 7/2/2010
Citation: Dumanski, 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. Strategies and Economics for Greenhouse Gas Mitigation in Agriculture. In: Stigter, K. (ed.), Applied Agrometeorology. Springer, Heidelberg, Germany. pp 1101. Book Chapter.

Interpretive Summary:

Technical Abstract: INTRODUCTION Agriculture can make significant contributions to climate change mitigation by a) increasing soil organic carbon sinks, b) reducing GHG emissions, and c) off-setting fossil fuel by promoting biofuels. The latter has the potential to counter-balance fossil-fuel emissions to some degree, but the overall impact is still uncertain compared to emissions of non-CO2 GHGs, which are likely to increase as production systems intensify. Agricultural lands also remove CH4 from the atmosphere by oxidation, though less than forest lands (Tate et al., 2006; Verchot et al., 2000), but this effect is small compared to other GHG fluxes (Smith and Conen, 2004) The main GHGs from agriculture are CO2, CH4, and N2O, and collectively these account for 10- 20 % of the annual increase in radiative forcing, and up to one third when land use change is included (IPCC, 2007). Agriculture accounts for between 59 and 63 % of the world’s non-CO2 GHG emissions, including 84 % of the global N2O emissions and 54 % of the global CH4 emissions (USEPA, 2006). Of these, N2O emissions from soils are the most important, followed by CH4 from enteric fermentation. Methane from rice cultivation is the third largest source. Deforestation is another major source of GHG emissions (about 7.6 Pg CO2 e/ yr). Direct emissions from fossil fuel account for about 10 % from this sector (Verchot, 2007). Non-CO2 GHG emissions from agriculture are expected to increase significantly in the future, with soil emissions of N2O (75 %) and CH4 from enteric fermentation (70 %) being the largest sources. Enteric fermentation and emissions from manure are expected to increase significantly, and become about 50 % greater than in 1990 (USEPA, 2006). These emissions are driven by production pressures, which in turn are driven by global processes such as world population density, globalization, urbanization, increased purchasing power of the middle classes, etc (Dumanski, 2008). Increased consumption of meat products as societies become more affluent is an important driver for emissions from enteric fermentation. All of these are expected to increase in the future, particularly in tropical countries. STRATEGIES FOR MITIGATING GHG EMISSION IN AGRICULTURE Recently, there have been significant improvements in farm management practices with a resulting increase in the carbon efficiency of agricultural production. Notably, while N2O and CH4 emissions have increased because of increasing levels of food production, the GHG emissions per unit of production have decreased. In Canada for example, GHG emissions per kilogram of beef cattle live weight have decreased from 13.9 to 10.4 kg CO2e from 1991 to 2006 (Verge et al., 2008a). During the same period, the GHG emission intensities for pork and poultry have decreased by 29 and 16% respectively (Verge et al 2008 b,c). Mitigation of climate change in agriculture requires adoption of integrated farming systems, since these capture the synergy of multiple practices and have the potential to reverse the decline and actually increase the soil organic carbon pool. Practices such as zero tillage (ZT) have the combined effect of soil carbon sequestration while concurrently reducing fossil fuel use and improving biodiversity. Other mitigation measures include agronomic practices such as improved crop varieties, improved crop rotations, and improved fertilizer management. Better residue and water management in rice can yield significant reductions of CH4 emissions. For livestock, there are a wide range of practices associated with grazing land management, improved feeding, and manure management that can reduce emissions and increase carbon sequestration. The collective impact of these practices is to reduce GHG emissions and sequester carbon in the soil. The IPCC (2000) identified three land use systems with significant global potentials for climate chan