Soil Salinization Influences Inorganic Carbon Storage and Distribution, According to Study

 

      A new global study published in the Proceedings of the National Academy of Sciences (PNAS) shows that increases in soil salinity are also changing the storage and distribution of soil inorganic carbon (SIC). The Chinese Academy of Sciences led the study, which integrated 94,515 soil profile samples from depths of 0–200 cm with land-use, climate, geomorphological, and soil-type information. The researchers then combined these data with machine learning-based spatial modeling.

     The researchers found that areas with high soil salinity, typically arid and semi-arid areas in Central Asia, West Asia, North Africa, western North America, and parts of South America, have disproportionately higher stocks of SIC. Soil electrical conductivity (EC), a standard salinity indicator, was used as a reliable proxy for SIC in surface and shallow soil layers (0–40 cm) across most environmental settings. EC correlated with SIC for most settings. However, the relationship was not universal, and there were some exceptions based on thresholds, land use factors, and soil depth.

“When EC increases beyond a moderate level (approximately 4 dS/m) or is found in deeper soil layers below 40 cm, though, the relationship between salinity and inorganic carbon weakens and can even reverse in some regions.”

“These patterns indicate that under high-salinity and alkaline conditions, changes in ionic composition, pH, and increased water transport can affect the long-term stability of the inorganic carbon pool.”

"Our results show that soil salinization does not lead to a simple linear increase in inorganic carbon storage," said Xue. "Instead, it largely depends on salinity levels, soil depth, and environmental context. Recognizing these limiting factors is crucial for accurately assessing the role of saline soils in the global carbon cycle."

“This study systematically reveals a conditional, threshold-dependent relationship between soil salinization and inorganic carbon on a global scale, filling a long-standing gap in understanding SIC and its driving mechanisms in global carbon cycle research. The findings provide new constraints for global carbon assessments and underscore the need to incorporate soil chemical processes into land degradation assessments and carbon neutrality strategies.”

     The abstract, shown below, points out that:

“These findings elucidate the dynamics of carbon–salt coupling in the soil–atmosphere–water system, offering pivotal scientific insights for carbon-neutrality strategies.”

References:

 

Increased soil salinity alters global inorganic carbon storage, finds study. Zhang Nannan. Phys.org. January 22, 2026. Increased soil salinity alters global inorganic carbon storage, finds study

The contribution of increased global soil salinity to changes in inorganic carbon. Xiaofang Jiang and Xian Xue. PNAS. Vol. 123 | No. 4.  January 21, 2026. The contribution of increased global soil salinity to changes in inorganic carbon | PNAS