Regional Simulation of Soil Organic Carbon Dynamics for Dry Farmland in East China by Coupling a 1:500000 Soil Database with the Century Model
Changes in soil organic carbon (SOC) in agricultural soils influence soil quality and greenhouse gas concentrations in the atmosphere. Therefore, estimating and understanding SOC dynamics in agricultural soils at regional levels is crucial from the perspective of sustainable landscape management and global change feedback. Simulation models are useful tools for analyzing the mechanisms controlling SOC dynamics in soils. The Century model is one of the most extensively used and well validated soil organic matter (SOM) models worldwide. It has been used to simulate SOC dynamics for cropland all over the world from both field scale based on long-term field experiments and regional and national scales by coupling it with GIS polygon data and grid data. Dry farmland covers more than 70％ of the whole cropland area in China and plays an important role in mitigating carbon dioxide (CO2) emissions. Consequently, an accurate estimation of SOC dynamics for dry farmland at the regional scale is vital for understanding the contribution of dry farmland to the national carbon inventory. In this study, a total of 4 109 dry farmland soil polygons were extracted by using spatial overlay analysis of the fine-scale soil database (1:500 000) and the land use database (1:500 000) to support Centuiy model simulations of SOC dynamics for dry farmland in the Anhui Province, East China from 1980 to 2008. Considering two fieldvalidation sites, the Century model performed relatively well in modeling SOC dynamics for dry farmland in the province. The simulated results showed that only 10.5％ of all the 4 109 polygons lost carbon. The area-weighted mean soil organic carbon density (SOCD) of dry farmland increased from 18.77 Mg C ha-1 in 1980 to 23.99 Mg C ha-1 in 2008 with an average sequestration rate of 0.18 MgC ha-1yr-1. The net SOC gain in dry farmland soils of the province was 19.37 Tg, with an average sequestration rate of 0.67 Tg C yr-1, indicating that upland soils of the province was a carbon sink over the past 29 years. Augmentation of SOC was primarily due to increased consumption of nitrogen fertilizer and farmyard manure. Approximately 94.9％ of the total dry farmland area sequestered carbon while 5.1％ lost carbon. Moreover, SOC dynamics were highly differentiated among dry farmland soil groups. Soil groups with low native SOCD sequestered carbon all the time while soil groups with high native SOCD lost carbon at the first 10 years and then began to sequester carbon. The integration of the Century model with a finescale soil database approach could be conveniently utilized as a tool for the accurate simulation of SOC dynamics at regional scales. As the quality of model input data about management practices was improved, more reasonable land use history was generalized, and a more precise soil database was developed, this temporal and spatial analysis approach could be applied to regionalizing strategies and policies for carbon sequestration to mitigate climate change.
Soil organic carbon (SOC) 1:500 000 soil database Century model Dry farmland Anhui Province
Shihang Wang Xuezheng Shi Yongcun Zhao Dongsheng Yu Shengxiang Xu Weixia Sun
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy
国际会议
北京
英文
81-82
2010-06-27（万方平台首次上网日期，不代表论文的发表时间）