Exogenous calcium-induced carbonate formation to increase carbon sequestration in coastal saline-alkali soil

• Published in: The Science of the total environment Vol. 946; p. 174338
• Main Authors: Xiang, Jian, Shi, Wenzhu, Jing, Zhenjiao, Guan, Yaling, Yang, Fengmin, Wang, Genmei, Sun, Xi, Li, Jiaxin, Li, Qing, Zhang, Huanchao
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.10.2024
• Subjects: CO2; Coastal saline-alkali soil; SIC; SOC; Soil carbon sequestration; Coastal saline-alkali soil; SIC; SOC; Soil carbon sequestration; CO2; CO
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.174338

Promoting soil carbon sequestration is a possible way to mitigate global warming. To investigate the effects of exogenous calcium on soil carbon sequestration during the application of organic matter to improve coastal saline-alkali soil. In this study, a 30-day incubation experiment was based on the application of corn straw biochar + chicken manure (BM) and rice straw + chicken manure (SM). Usages of exogenous calcium in each treatment under each organic matter combination as follow: CK (No exogenous calcium), CaSi1 (1.24 g CaSiO3, i.e. 4.28 g Ca kg−1 soil), CaSi2 (2.48 g CaSiO3, i.e. 8.56 g Ca kg−1 soil), CaOH1 (0.79 g Ca(OH)2, i.e. 4.28 g Ca kg−1 soil), CaOH2 (1.58 g Ca(OH)2, i.e. 8.56 g Ca kg−1 soil), CaSiOH (1.24 g CaSiO3 + 0.79 g Ca(OH)2, i.e. 8.56 g Ca kg−1 soil). Results showed that exogenous calcium significantly reduced CO2 emission. Organic matter addition promoted the loss of SOC, and exogenous did not significantly affect the mineralization of SOC albeit strongly increased SIC, making up for the loss of SOC, increasing soil total carbon and realizing soil carbon fixation. Soil carbon fixation was mainly realized by the reaction of exogenous calcium with CO2 generated by mineralization and converting it into calcium carbonate. pH and soil CO2 emission are the major controlling factors for soil inorganic carbon sequestration. Therefore, applying organic matter with exogenous calcium can realize soil carbon fixation by generation of calcium carbonate. [Display omitted] •Exogenous calcium strongly decreased soil CO2 emission, and Ca(OH)2 had a better effect.•Exogenous calcium makes up for the loss of SOC by promoting the generation of SIC to increase the TC content.•Soil carbon sequestration was through exogenous calcium reacting with CO2 from mineralization and converting to SIC.•pH and soil CO2 emission are the major factors that affect soil inorganic carbon sequestration.