Soil organic carbon (SOC) is the most important indicators of soil quality and health. Identifying the spatial distribution of SOC and its influencing factors in cropland is crucial to understand the terrestrial carbon cycle and optimize agronomic management. Yunnan Province, characterized by mountainous topography and varied elevation, is one of the highest SOC regions in China. Yet its SOC stock of cropland and influencing factors has not been fully studied due to the lack of adequate soil investigation. In this study, the digital mapping of SOC at 1 km resolution and the estimation of total SOC stock in cropland of Yunnan Province was undertaken using 8637 topsoil (0–20 cm) samples and a series of spatial data through Random Forest (RF) model. It was showed that across the cropland of Yunnan Province, the mean SOC density and total stock were 4.84 kg m–2 and 337.5 Mt, respectively. The spatial distribution indicated that relatively high SOC density regions resided in the northwest and northeast parts of Yunnan Province. Elevation (19.5％), temperature (17.3％), rainfall (14.5％), and Topographic wetness index (9.9％) were the most important factors which controlled spatial variability of SOC density. Agronomic practices (e.g., crop straw treatments, fertilizer management) should be optimized for the sustainable development of crop production with high SOC sequestration capacity in Yunnan Province.

Institute of Crop Sciences,Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and Ecology,Ministry of Agriculture and Rural Affairs,Beijing 100081,P.R.China;Yunnan Academy of Tobacco Agricultural Sciences,Kunming 650021,P.R.China;Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences,Beijing 100081,P.R.China;China Tobacco Company Yunnan Branch,Kunming 650011,P.R.China

[1]SUN Tao;TONG Wen-jie;CHANG Nai-jie;DENG Ai-xing;LIN Zhong-long;FENG Xing-bing;LI Jun-ying;SONG Zhen-wei-.Estimation of soil organic carbon stock and its controlling factors in cropland of Yunnan Province, China)[J].农业科学学报（英文）,2022(05):1475-1487

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