Yan XY Cai ZC Wang SW et al.. Direct measurement of soil organic carbon content change in the croplands of China. Global Change Biology 2011 17(3): 1487-1496. (IF 6.346 环境科学，一区）
Abstract
Agricultural soils in China have been estimated to have a large potential for carbon sequestration and modelling and literature survey studies have yielded contrasting results of soil organic carbon (SOC) stock change ranging from -2.0 to +0.6% yr-1. To assess the validity of earlier estimates we collected 1394 cropland soil profiles from all over the country and measured SOC contents in 2007-2008 and compared them with those of a previous national soil survey conducted in 1979-1982. The results showed that average SOC content in the 0-20 cm soil increased from 11.95 g kg-1 in 1979-1982 to 12.67 g kg-1 in 2007-2008 averaging 0.22% yr-1. The standard deviation of SOC contents decreased. Four major soil types had statistically significant changes in their mean SOC contents for 0-20 cm. These were: +7.5% for Anthrosols (paddy soils) +18.3% for Eutric Cambisols +30.5% for Fluvisols and -22.3% for Chernozems. The change of SOC contents showed a negative relationship with the average SOC contents of the two sampling campaigns only when soils in the region south of Yangtse River were excluded. SOC contents of the two major soil types in the region south of Yangtse River i.e. Haplic Alisols-Haplic Acrisols and Anthrosols (paddy soils) changed little or significantly increased though with a high SOC content. We suggest that the increase of SOC content is mainly attributed to the large increase in crop yields since the 1980s and the short history as cropland establishment is mainly responsible for the decrease in SOC content for some soil types and regions showing a SOC decline.
