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.

Orcid ID

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

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