Poorly crystalline iron and aluminium oxides contribute to the carbon saturation and sorption of dissolved organic carbon in the soil

• Published in: Soil use and management 2021-01, Vol.37 (1), p.120-125
• Main Authors: Khandakar, Tania, Guppy, Chris, Rabbi, Sheikh M. F., Daniel, Heiko
• Format: Article
• Language: English
• Subjects: adsorption; Aluminium; Aluminum; Aluminum oxide; Carbon; carbon saturation deficit; Chemical control; Clay; Crystal structure; Crystallinity; Desorption; Destabilization; Dissolved organic carbon; initial mass isotherm; Iron; Land use; Organic soils; Oxides; Pasture; Saturated soils; Saturation; Silt; Soil; Soil stabilization; Soils; Sorption
• ISSN: 0266-0032; 1475-2743
• DOI: 10.1111/sum.12662

Soil carbon (C) saturation implies an upper limit to a soil's capacity to store C depending on the contents of silt + clay and poorly crystalline Fe and Al oxides. We hypothesized that the poorly crystalline Fe and Al oxides in silt + clay fraction increased the C saturation and thus reduced the capacity of the soil to sorb additional C input. To test the hypothesis, we studied the sorption of dissolved organic carbon (DOC) on silt + clay fractions (15 g kg−1). While high Al oxide concentration significantly increased both the saturation and desorption of DOC, the high Fe oxide concentration significantly increased the desorption of DOC, supporting the proposition that both oxides have influence on the DOC sorption in soil. Our findings provide a new insight into the chemical control of stabilization and destabilization of DOC in soil.