Projected changes in the organic carbon stocks of cropland mineral soils of European Russia and the Ukraine, 1990–2070 JO SMITH *, PETE SMITH *, MARTIN WATTENBACH *, PIA GOTTSCHALK *, VLADIMIR A. ROMANENKOV w , LUDMILA K. SHEVTSOVA w , OLEG D. SIROTENKO z, DMITRY I. RUKHOVICH§, POLINA V. KOROLEVA§, IRINA A. ROMANENKO } and NICOLAI V. LISOVOI k *School of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK, wPryanishnikov All-Russian Institute of Agrochemistry (VNIIA), Pryanishnikova St. 31a, 127550 Moscow, Russia, zAll-Russian Institute of Agricultural Meteorology, Lenina St. 82, Obninsk, Kaluga Region, 249020 Russia, §Dokuchaev Soil Science Institute, Pyzhevsky Per., 7, 109017 Moscow, Russia, }All-Russian Institute of Agricultural Problems and Informatics, Kharitonievsky per., 21/6 Bld.1, 103064 Moscow, Russia, kInstitute for Soil Science and Agrochemistry Research named after O.N. Sokolovsky, Chaikovskogo St. 4, 61024 Kharkiv-24, Ukraine Abstract In this paper, we use the Rothamsted Carbon Model to estimate how cropland mineral soil carbon stocks are likely to change under future climate, and how agricultural management might influence these stocks in the future. The model was run for croplands occurring on mineral soils in European Russia and the Ukraine, representing 74 Mha of cropland in Russia and 31 Mha in the Ukraine. The model used climate data (1990–2070) from the HadCM3 climate model, forced by four Intergovernmental Panel on Climate Change (IPCC) emission scenarios representing various degrees of globalization and emphasis on economic vs. environmental considerations. Three land use scenarios were examined, business as usual (BAU) management, optimal management (OPT) to max- imize profit, and soil sustainability (SUS) in which profit was maximized within the constraint that soil carbon must either remain stable or increase. Our findings suggest that soil organic carbon (SOC) will be lost under all climate scenarios, but less is lost under the climate scenarios where environmental considerations are placed higher than purely economic considerations (IPCC B1 and B2 scenarios) compared with the climate associated with emissions resulting from the global free market scenario (IPCC A1FI scenario). More SOC is lost towards the end of the study period. Optimal management is able to reduce this loss of SOC, by up to 44% compared with business as usual management. The soil sustainability scenario could be run only for a limited area, but in that area was shown to increase SOC stocks under three climate scenarios, compared with a loss of SOC under business as usual management in the same area. Improved agricultural soil management will have a significant role to play in the adaptation to, and mitigation of, climate change in this region. Further, our results suggest that this adaptation could be realized without damaging profitability for the farmers, a key criteria affecting whether optimal management can be achieved in reality. Keywords: cropland, RothC model, Russia, soil carbon, Ukraine Received 9 August 2005; revised version received 17 March 2006 and accepted 1 May 2006 Introduction Russia has recently ratified the Kyoto Protocol to the 1992 United Nations Framework Convention on Climate Change (UNFCCC; available at: www.unfccc.de), Correspondence: Jo Smith, tel. 1 44 1224 272702, fax 1 44 1224 272703, e-mail: jo.smith@abdn.ac.uk Global Change Biology (2007) 13, 342–356, doi: 10.1111/j.1365-2486.2006.01297.x r 2007 The Authors 342 Journal compilation r2007 Blackwell Publishing Ltd