The Role of Cropland Soil Carbon Sequestration in Greenhouse Gas Mitigation and Potential in China.

Abstract
With an understanding that agricultural soils hold potential for expanded carbon sequestration, we investigated the contribution of cropland soils to greenhouse gas mitigation in China based on an analysis of datasets extracted from the literature. Results indicated that a significant increase in SOC occurred in eastern and northern China, whilst a sharp decrease appeared in northeastern China over the period 1980–2000. An overall estimate suggested that the SOC stocks in topsoil (0–30 cm) of 130 Mha croplands in China increased by 437(331–555) Tg, 21.8(16.6–27.8) Tg per year on average that corresponds to offset 2.6 (2.0–3.3) % of annual CO₂ emission from energy consumption and industrial processes, or 12.8 (9.7–16.3) % and 23.4 (17.8–29.8) % of the total CH₄ and N₂O emissions from croplands at 20-year and 100-year time horizons, respectively. A possible potential in SOC sequestration was estimated to be 2–2.5 Pg C in China, which could be achieved by the 2050s when cropland management is improved.

Key words: cropland, soil, carbon sequestration, greenhouse gas mitigation, potential, China