Modelling soil organic carbon dynamics in the major agricultural regions of China

This paper reports a modelling study on long-term (20 years) impacts of present and alternative farming management practices on (SOC) dynamics. A well documented, process-based model, DNDC, was employed, depending on the local climate, soil and management conditions in the six regions. Modelled results indicated that, under the present management conditions, the SOC status in the three northern sites (i.e., Qiqihar, Miyun and Pingliang) where upland crops dominated appeared more dynamic than that in the three southern sites (i.e., Zhijiang, Jiangning and Yantin) where paddy rice dominated. During the simulated 20 years, the northern sites were either losing or gaining SOC at relatively high rates from -1000 to 200 kg C/ha/yr; and the southern sites had relatively stable SOC contents with deviations ranging from -70 to 26 kg C/ha/yr. Increase in the fraction of above-ground crop residue incorporated in soil or application of manure effectively converted most of the tested sites into sinks of atmospheric Carbon. Since crop residue and manure resources are available in most of the agricultural regions, adaptation of the management alternatives should be feasible in China. (C) 2008 Elsevier B.V. All rights reserved.