Revealing the unforeseen role and sensitivity of anoxic protection in soil carbon cycling
Abstract/Contents
- Abstract
- Increasing soil carbon (C) content promises to mitigate climate change and enhance soil fertility. Soil C content is determined, in part, by microbial respiration, which converts soil C into carbon dioxide. Carbon protection mechanisms represent processes and conditions that limit microbial respiration of soil C. Anoxic microsites, zones of oxygen depletion in otherwise oxic soils, are a recently recognized and under-studied soil C protection mechanism. In this dissertation, I use field and laboratory methods to determine the extent and contribution of anoxic microsites to soil C protection within natural and agricultural systems. In Chapter 2, I measure the dissolved oxygen content of soil porewater from California agricultural soils. I show that physical disturbance destroys anoxic microsites through enhancing oxygen supply to the smallest soil pores. In Chapter 3, I show that oxygen limitations constrain OM turnover in a Hawaiian rainforest soil, an environment where mineral content is presumed to be the dominant soil C protection mechanism. In Chapter 4, I examine a soil textural gradient at the Stanford Dish and demonstrate that anoxic microsites are particularly important for protecting C in coarsely textured soils. Finally, in Chapter 5, I use droplet digital PCR to quantify anaerobe DNA (a proxy for anoxic microsites) in soils from four long-term agricultural experiments across the continental United States. I show that anoxic microsites vary with soil properties, respond to management, and uniquely contribute to soil C stabilization within cropland soils. In sum, this dissertation reveals that anoxic microsites represent a vulnerability in the soil C stock but also an opportunity to enhance soil C storage.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Lacroix, Emily Morgan |
|---|---|
| Degree supervisor | Fendorf, Scott |
| Thesis advisor | Fendorf, Scott |
| Thesis advisor | Chadwick, Oliver A |
| Thesis advisor | Dekas, Anne |
| Thesis advisor | Jackson, Rob, 1961- |
| Degree committee member | Chadwick, Oliver A |
| Degree committee member | Dekas, Anne |
| Degree committee member | Jackson, Rob, 1961- |
| Associated with | Stanford University, Department of Earth System Science |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Emily Morgan Lacroix. |
|---|---|
| Note | Submitted to the Department of Earth System Science. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/cp952gp7270 |
Access conditions
- Copyright
- © 2022 by Emily Morgan Lacroix
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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