Using Micrometeorology to Gauge Agriculture's Potential to Sequester Soil Carbon

Author

Debra Blumberg O'Dell, University of Tennessee

Orcid ID

http://orcid.org/0000-0003-4968-2287

Date of Award

5-2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Plant, Soil and Environmental Sciences

Major Professor

Neal S. Eash

Committee Members

Thomas J. Sauer, Dayton M. Lambert, Joanne Logan, Bruce B. Hicks, James A. Zahn

Abstract

In addition to reducing carbon dioxide (CO₂) emissions from fossil fuel combustion, removing atmospheric CO₂ may be critical to limit global warming to less than two degrees Celsius above pre-industrial levels recommended by leading experts. Since cropland occupies 11% of the earth’s land and is intensively managed, cropland agriculture provides one approach for removing CO₂ from the atmosphere to mitigate climate change. However, current assessments indicate agriculture is a net emitter of CO₂ and other greenhouse gases, and it is unclear how soil management can effect carbon sequestration.In this work micrometeorological methods are used to measure the exchange (flux) of CO₂ between the surface and atmosphere and can assess whether an agricultural ecosystem is a source or sink for carbon. Three studies were performed using micrometeorology to understand agriculture’s potential to sequester carbon.Using Bowen Ratio Energy Balance (BREB) micrometeorological methods, the first study measured CO₂ flux from a maize crop grown on no-till and tilled soils to determine tillage effects on CO₂ emissions during 104 days of the 2015 maize growing season in north central Ohio. During this period, the no-till plot sequestered CO₂, while the tilled plot was a net emitter.A second study determined if industrial biotechnology waste reutilization in agriculture could reduce CO₂ emissions and generate environmental benefits, while meeting farmer yield expectations. Using both BREB and eddy covariance (EC) micrometeorological methods, CO₂ flux was measured over maize where heat-inactivated, spent microbial biomass (SMB) amendment was land applied and compared with typical farmer practices from October 2016 to October 2017 in Loudon, Tennessee. While treatments with SMB emitted more CO₂ than farmer practices, the SMB applications produced yields similar to farmer practices.Using BREB micrometeorology methods, the third study measured CO₂ emissions over conservation agriculture (CA) practices as compared to conventional tillage from June 2013 to May 2016 in central Zimbabwe. The CA practices of no-till and cover crops produced significantly fewer CO₂ emissions than conventional tillage.These studies demonstrate that micrometeorology can detect short- and long-term differences in CO₂ flux between practices, providing data supporting agriculture’s potential to reduce CO₂ emissions and sequester carbon.

Recommended Citation

O'Dell, Debra Blumberg, "Using Micrometeorology to Gauge Agriculture's Potential to Sequester Soil Carbon. " PhD diss., University of Tennessee, 2019.
https://trace.tennessee.edu/utk_graddiss/5349