The Relationship Between Specific Surface Area and Soil Organic Carbon in Loess Derived Soils, of Northern Iran.

Soil organic carbon (SOC) can act as a sink or source of atmospheric carbon dioxide, therefore, it is important to understand the amount and composition of SOC in terrestrial ecosystems, the spatial variation in SOC, and the underlying mechanisms that stabilize SOC.

 Relationships between mineral specific surface area and organic carbon (OC) concentration were examined for sediments and soil A-horizons from throughout the world. The organic compositions can be adsorbed by minerals surface, and also exist a positive relation between SSA and OC. Much of our current understanding is based on laboratory experiments, the results of which often do not support observations made in the field. The present study attempted to demonstrate the relationship between specific surface area, soil organic carbon (SOC) rate and clay content in the pasture soils, in Golestan province. 7 soil profiles informed different moisture regimes (Udic, Xeric and Aridic regimes) were sampled from surface horizon (depth 0-30cm). Correlation and linear regressions were performed between SOC, specific surface area (SSA) and particle clay size. Results indicate that SOC and the content of clay showed significant liner correlations with SSA (r=0.66, 0.64 respectively, p<0.05). Saggar et al., 1996 demonstrated that mean residence time of organic carbon in soil increase with higher specific surface area. Soils with high clay levels show greater SOC than soils with high sand contents.