Study of loss or gain of soil organic carbon in Da'an region, Jilin Province in China

Soil organic carbon changes monitoring is of importance to identify sources or sinks of atmospheric CO2. Multi-period soil organic carbon (SOC) data in Da'an region, Jilin Province in Northeast China, were obtained by National Soil Survey, the National Multi-Purpose Regional Geochemical Survey (NMPRGS) project. Loss or gain of SOC was estimated during 1984-2004. Results show the clear trend of carbon loss from soil to the atmosphere in the period, with a smaller SOC decrease rate in 2004-2008 than the rate in 1984-2004. The NMPRGS project has been carried out since 1999 by collecting topsoil samples (0-20 cm) with an average density of one sample per 1 km(2) and one composite sample per 4 km(2) for analyses. An area of 1,650,000 km(2) has been covered by the survey up to 2010 in China. Based on the large amount of SOC data, a new project has been launched to study the loss and gain of soil organic carbon across China, which will provide the basic information to improve the land use management and agricultural operations in the country. (C) 2011 Elsevier B.V. All rights reserved.