Estimation of Deep Soil Organic Carbon in Yunnan Province and Its Influencing Factors

PurposeSince the deep soil organic carbon pool is a vital component of the terrestrial carbon pool, we studied the content of deep soil organic carbon in Yunnan Province and its influencing factors, which are of great significance to the migration of pollutants in Yunnan soil and the growth of crops.

MethodThe soil organic carbon density (SOCD) and soil organic carbon reserves (SOCR) from deep soils were estimated based on 570 soil profile from the second soil survey data of Yunnan Province by soil type method. Besides, the spatial distribution map of SOCD was drawn by ArcGIS, and its influencing factors were studied by single factor analysis.

Result According to the estimation by Van Bemmelen coefficient, the value of 30-200 cm average SOCD in Yunnan Province was 44.21 t/hm², and the total SOCR in Yunnan Province was 1.67×10⁹ t. The deep SOCD gradually increased from the Southeast to the Northwest of Yunnan, which was similar to the SOCD change pattern of the surface soil in Yunnan Province. Meanwhile, the distribution of deep SOCD was affected by altitude, precipitation, and temperature. The deep SOCD values were positively correlated with altitude and average annual precipitation, while the temperature was negatively correlated with deep SOCD.

ConclusionThe SOCD of deep soil in Yunnan Province was greater than the national average SOCD, but both were less than the SOCD of 0-20 cm surface layer in Yunnan Province. This research is of great significance to the study of deep soil organic carbon in other regions in the future.