Spatiotemporal changes in greenhouse gas emissions and soil organic carbon sequestration for major cropping systems across China and their drivers over the past two decades

Yicheng Wang; Fulu Tao; Lichang Yin; Yi Chen

doi:10.1016/j.scitotenv.2022.155087

Spatiotemporal changes in greenhouse gas emissions and soil organic carbon sequestration for major cropping systems across China and their drivers over the past two decades

Sci Total Environ. 2022 Aug 10:833:155087. doi: 10.1016/j.scitotenv.2022.155087. Epub 2022 Apr 11.

Authors

Yicheng Wang¹, Fulu Tao², Lichang Yin¹, Yi Chen¹

Affiliations

¹ Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
² Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Natural Resources Institute Finland (Luke), Helsinki 00790, Finland. Electronic address: taofl@igsnrr.ac.cn.

PMID: 35421495
DOI: 10.1016/j.scitotenv.2022.155087

Abstract

Chinese agricultural systems have experienced dramatic changes in crop planting area, cropping system, irrigation and fertilization managements, and crop yields in recent decades. These changes can substantially affect greenhouse gases (GHG) emissions and soil organic carbon (SOC) sequestration in croplands. However, the spatiotemporal patterns, as well as their driving factors and mechanisms, have not been well understood. Here, the Denitrification-Decomposition model is calibrated and validated to estimate nitrous oxide (N₂O) and methane (CH₄) emissions and SOC sequestration for seven major cropping systems in China during 2001-2020. The Logarithmic Mean Divisia Index method is further applied to attribute the net GHG emissions (NGEs) trend to various drivers. The results show that the total N₂O emissions, CH₄ emissions, and SOC sequestration were approximately 23.7, 182.0, and 177.6 Tg CO₂-eq/year in the croplands across China. The national average NGEs per unit area ranged from -8705 to 8431 kg CO₂-eq ha^-1 year^-1 across the major cropping systems. During 2001-2020, the trend in national annual NGEs was 0.66 kg CO₂-eq ha^-1 year^-2, ranging from -78.9 to 82.2 kg CO₂-eq ha^-1 year^-2 across the major cropping systems. The paddy lands were mainly a carbon source due to the large amount of CH₄ emissions while the uplands could be a carbon sink owing to SOC sequestration. As a whole, the cropland in China was a carbon source with the NGEs equal to 28.4 Tg CO₂-eq/year, and the NGEs increased by 0.047 Tg CO₂-eq/year² in the past 20 years. Nationally, changes in crop planting area and yields reduced the NGEs whereas changes in nitrogen use efficiency and cropping systems increased them, although the major factors and their impacts varied greatly among regions. Optimizing cropping systems and nitrogen fertilization based on the local genotype, environment and management should be the most effective method to reduce the NGEs in croplands.

Keywords: Agricultural system; Carbon cycle; Climate smart agriculture; GHG emissions; Mitigation; SOC.

MeSH terms

Agriculture / methods
Carbon / analysis
Carbon Dioxide / analysis
Carbon Sequestration
China
Greenhouse Effect
Greenhouse Gases*
Methane / analysis
Nitrogen
Nitrous Oxide / analysis
Soil

Substances

Greenhouse Gases
Soil
Carbon Dioxide
Carbon
Nitrous Oxide
Nitrogen
Methane