Date of Award
2012
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Graduate Group
Earth & Environmental Science
First Advisor
Alain F. Plante
Second Advisor
Arthur H. Johnson
Abstract
Soil carbon (C) stocks and fluxes represent significant components of the global C cycle. Application of the soil C saturation theory can help identify soils with large C storage potentials and estimate rates and durations needed to reach maximal soil C storage. The goal of my dissertation was to test the soil C saturation theory by estimating C saturation levels of fine soil particles and quantifying changes in soil organic matter (SOM) stability as fine soil particles approach C saturation. Current model using least-squares linear regression generally underestimates C the maximal amount of soil C stabilization in fine soil particles. Using an analysis of published data, I proposed two alternative methods (boundary line analysis and the organic C loading method) to improve estimates, and found that while the organic C loading method is better since it incorporated mineral specific surface areas which would influence C saturation, it requires information about soil mineralogy and further tests to determine whether the monolayer-equivalent C loading indeed represents a maximal C stabilization potential. Laboratory batch sorption experiment of dissolved organic matter onto soil minerals generated organo-mineral complexes with a range of organic C loadings. These organo-mineral complexes, as well as silt+clay fractions physically isolated from soil samples from three long-term agroecosystem field experiments with differing fertilizer and manure addition treatments, were used to test for differences in SOM stability as a function of organic C loading. Biological, chemical, and thermal test of SOM stability showed little change or the increase trend of SOM stability with increasing organic C inputs, which do not support the notion of the soil C saturation theory that SOM stability decreases as organic C inputs increase. This observation of SOM stability is likely due to the fact that most samples did not exhibit C saturation behavior. The results show that most soils are likely well below C saturation, and further studies of the driving factors (e.g., chemical composition of organic C inputs, mineralogy, and organo-mineral binding types and strength) is needed to determine maximal C loadings and estimate the maximal soil C storage potentials.
Recommended Citation
Feng, Wenting, "Testing the Soil Carbon Saturation Theory: Maximal Carbon Stabilization and Soil Organic Matter Stability as a Function of Organic Carbon Inputs" (2012). Publicly Accessible Penn Dissertations. 507.
https://repository.upenn.edu/edissertations/507
Included in
Ecology and Evolutionary Biology Commons, Environmental Sciences Commons, Soil Science Commons