中国农田土壤生态系统固碳现状和潜力

Soil carbon sequestration and its potential by cropland ecosystems in China

研究在搜集和整理全国典型农业长期定位实验站数据的基础上,通过自建经验公式估算了不同管理措施下我国农田土壤的固碳能力和潜力。通过施用化肥、秸秆还田、施用有机肥和免耕措施,目前对我国农田土壤碳增加的贡献分别为40.51、23.89、35.83 Tg.a-1和1.17 Tg.a-1,合计为101.4 Tg.a-1,是我国目前能源活动碳总排放量的13.3%。通过情景分析发现,提高化肥施用量、秸秆还田量、有机肥施用量和推广免耕,可以使我国农田土壤的固碳量分别提高到94.91、42.23、41.38 Tg.a-1和3.58 Tg.a-1,合计为182.1Tg.a-1。农田土壤总的固碳潜力相当于目前我国能源活动碳排放量的23.9%,对于全球CO2减排具有重要的作用。

Rising atmospheric carbon dioxide concentration is a concern because of its potential for altering climate. Since the beginning of the Industrial Revolution in the 18th century, atmospheric CO2 has increased by more than 30%. The increase in fossil fuel burning and associated CO2 emissions is expected to continue for the foreseeable future, and a double or even tripling of the preindustrial concentration of atmospheric CO2 is possible by the end of the 21st century. Some authors have thought agricultural soils could sequester a considerable carbon to slow the rise of the atmospheric CO2. In fact, this sequestering potential depends on initial soil content, climate and cultivation. The long-term experiments in North America have proved that arable lands have been changing from a C source to sink by conservation management, such as reduced- and no-till practice, manure use, rotation, and introducing cover crops. From the point of view of agricultural management, to keep the sustainable development and realize the carbon sequestration potential is crucial to both crop production and carbon mitigation. The contribution of China＇s agricultural practice to atmospheric CO2 has been paid a great attention because China has a long history of agriculture to support one-fifth of global population. In this study, based on domestic typical long-term field experiment data, experiential models were constructed to estimate the carbon sequestration status and potential of agricultural soil under different managements in China. In currentsituation, the carbon sequestration in agricultural soil of N fertilizer use, residue return, manure use and zero-tillage, were 40.51,23.89,35.83Tg·a^-1 and 1.17Tg·a^-1, respectively. The total carbon sequestration capacity was 101.4 Tg·a^-1, which was equal to 13.3% of the annual carbon emission from fossil fuel use in China. In the scenarios of increased N fertilizer use, popularization of residue return, manure use and zero-tillage, the carbon sequestration potential can reach 94.91,42.23, 41.38Tg·a^-1 and 3.58 Tg·a^-1, respectively. These management measures are very important to CO2 mitigation since the total carbon sequestration potential accounts for 23.9% of the annual carbon emission from fossil fuel use in China.