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Stabilization mechanisms of organic carbon in two soils of the Midwestern United States

Jagadamma, Sindhu
http://rave.ohiolink.edu/etdc/view?acc_num=osu1241450699

Abstract Details

2009, Doctor of Philosophy, Ohio State University, Soil Science.
The soil organic carbon (SOC) pool is very important as a potential sink of C over human time scales. In order to evaluate the potential of soils as a long-term C sink in response to changing management and climate, it is essential to be able to experimentally partition different SOC fractions. Despite many advances in the understanding of SOC dynamics, numerous uncertainties still exist in the separation of SOC fractions with distinct stability. Therefore, the overall objective of this research was to acquire a better understanding of the stable SOC fraction in terms of pool size, structural composition, and turnover rates in two soils of the Midwestern United States (Typic Fragiudalf of Wooster, OH and Aquic Argiudoll of Monmouth, IL). Both physical and chemical fractionation methods were employed to isolate the stable from labile SOC. Comparison of the commonly used chemical oxidizing agents, namely hydrogen peroxide (H2O2), disodium peroxodisulphate (Na2S2O8), and sodium hypochlorite (NaOCl), revealed that both H2O2 and Na2S2O8 are more effective than NaOCl in isolating a stable SOC fraction enriched with alkyl-C groups and a radiocarbon age of thousands of years old. Evaluation of the physical fractions indicated that (i) sand and silt-associated SOC quickly changed with conversion from native vegetation to agricultural crops, and (ii) the clay associated SOC in agricultural soils of Wooster continues to increase, albeit at a slower rate, with increase in total SOC, while it attained maximum saturation capacity in the Mollisol at Monmouth. In general, the pool size of the stable SOC fractions isolated by physical methods was significantly higher (10.7 to 64.8% of total SOC) than that isolated by chemical methods (1.3 to 25.6% of total SOC). Combining physical and chemical methods isolated a stable SOC fraction with longer stability in the surface soils than the individual methods, while the different methods did not influence substantially the turnover rates of the stable SOC pool in the subsoil. Results obtained from this study will strengthen the current knowledge on the efficiency of different fractionation methods for isolating the SOC fractions with distinct stability. Such information is very important for accurate quantification of the effects of land use or management changes on long-term stabilization of SOC, and also for the validation of SOC prediction models.
Rattan Lal (Advisor)
Jerry Bigham (Committee Member)
Peter Curtis (Committee Member)
Robert Hoeft (Committee Member)
177 p.
Soil Sciences
Soil organic carbon; fractionation methods; stable SOC; NMR spectroscopy; Radiocarbon age; 13C-natural abundance

Recommended Citations

Citations

  • Jagadamma, S. (2009). Stabilization mechanisms of organic carbon in two soils of the Midwestern United States [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1241450699

    APA Style (7th edition)

  • Jagadamma, Sindhu. Stabilization mechanisms of organic carbon in two soils of the Midwestern United States. 2009. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1241450699.

    MLA Style (8th edition)

  • Jagadamma, Sindhu. "Stabilization mechanisms of organic carbon in two soils of the Midwestern United States." Doctoral dissertation, Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1241450699

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.