Soil organic matter (SOM) is one of the most complex components of terrestrial ecosystems and serves many vital functions in terms of regulating the flow and supply of nutrients to plants, regulating water flow and water retention in soils and determining the physical attributes of soils. Hence, the maintenance and management of SOM is vital for the sustainability of croplands, grasslands, forests and wetlands. More recently, increased attention has been focused on the role of soils in the global carbon cycle, where the world’s soils contain more than 1.5 trillion tonnes of carbon or roughly three times the carbon contained in all the world’s vegetation and twice the amount of carbon (as CO2) in the earth’s atmosphere. Hence, relatively small changes in the global storage of carbon in SOM can have large effects on greenhouse gas (GHG) concentrations—either positively or negatively. If soils are managed to increase their organic matter content (which also contributes to increased soil fertility), CO2 levels in the atmosphere can be reduced. Currently there is a growing interest in promoting soil carbon sequestration as a GHG mitigation option, particularly in many developing countries. Incorporating carbon sequestration objectives in sustainable land management projects (both via the growing voluntary GHG offset markets and evolving national and international GHG mitigation policies) opens the possibility to radically improve the prospects for improved livelihoods and more sustainable land use practices in developing countries. Research directed at improving our understanding of, and ability to accurately predict, changes in SOM, across the range of managed ecosystems—from croplands, grazing lands, forests and wetlands—is moving very rapidly. Increasingly the science community is being called upon to provide the information and tools needed to support policies directed towards sustainable land use and GHG mitigation, involving SOM. With the overall aim to present the state-of-the-art on SOM studies across the world and highlight future research directions, the International Symposium on Soil Organic Matter Dynamics: Land Use, Management and Global Change was held in Colorado Springs, Colorado, USA, on July 6–9, 2009 (http:// www.nrel.colostate.edu/som-home.html). At the symposium, SOM dynamics were discussed in the context Plant Soil (2011) 338:1–3 DOI 10.1007/s11104-010-0617-6