Agricultural processes generate and cycle significant proportions of global greenhouse gases, but mitigating agricultural effects on climate will require new technologies whose impacts have not been thoroughly quantified. Agricultural soils and animals contribute approximately 40% of global methane (CH4) and nitrous oxide (N2O) emissions, and agricultural soils further act as atmospheric carbon dioxide (CO2) sources or sinks. Changes in land use and management influence source or sink status by affecting the carbon budget of the plant–soil system. According to Intergovernmental Panel on Climate Change assessment reports, improving agronomic practices, animal nutrition and animal waste management can significantly reduce greenhouse gas emissions from agricultural sources. Although various technologies for mitigating agricultural greenhouse gas emissions have been proposed and discussed, knowledge gaps remain. First, large uncertainties exist in quantitative technology evaluations because of climate and ecosystem diversity. Second, the primary focus on greenhouse gas emission mitigation efficiency for many proposed technologies has neglected feasibility and trade-offs between economy and production. Third, estimating mitigation effects of the technologies requires the development of methods to scale data up to regional or global scales.
Agricultural activities in Monsoon Asia have significantly influenced the atmosphere through greenhouse gas emissions. Monsoon Asia is a seasonally humid region that covers approximately 16% of the Earth's land surface and hosts approximately 60% of the world's human population. Rice cultivation and small-scale intensive agriculture, which are primarily family owned, dominate Monsoon Asian farming. Human activities have intensively disturbed or managed terrestrial ecosystems in Monsoon Asia for many centuries, and the area is now involved in rapid economic, social and environmental changes. As a result, many research issues are common among Monsoon Asian countries.
To address these issues, an International Workshop on Monsoon Asian Agricultural Greenhouse Gas Emissions (MAGE Workshop) was held from 7 to 9 March 2006 at the Tsukuba International Congress Center in Tsukuba, Japan. The workshop was sponsored by the National Institute for Agro-Environmental Science, the National Institute of Livestock and Grassland Science, the Japanese Society of Soil Science and Plant Nutrition, the Japanese Society of Animal Science, and the Global Environment Research Fund, Ministry of the Environment. The workshop hosted 24 oral and 28 poster presentations designed to communicate current understanding and to bridge knowledge gaps regarding agricultural greenhouse gas emissions in Monsoon Asia. The workshop attracted 110 participants from 10 countries and enabled them to discuss many aspects of cropland and livestock production related greenhouse gas emissions, including monitoring, modeling and mitigation options. Participants also explored future research directions and cooperation.
For this special section in Soil Science and Plant Nutrition (TSSP), two mini-reviews and three full-length papers were carefully selected from the oral and poster presentations at this workshop. These papers were submitted and peer reviewed using entirely the same processes as other papers published in TSSP.
We would like to thank all the individuals and institutions that supported the workshop and the TSSP Editorial Board for giving us the opportunity to publish this special section.