Measuring Carbon Dioxide (CO2) Flux of Agricultural Practices in Sub-Saharan Africa

Agriculture has an important role in addressing two of the world’s most pressing problems: meeting global food demand and mitigating climate change. If agriculture is not practiced sustainably it will fail to meet future food demand and likely intensify the pace of global climate change. There are some agricultural practices, such as Conservation Agriculture, that can produce food sustainably and have the potential to mitigate climate change. However it is not clear which agricultural practices contribute to climate mitigation and by how much. By measuring the carbon dioxide (CO2) emissions of specific agricultural practices, the ability of practices to sequester or emit carbon can be quantified and used in climate mitigation policies. Since there is a lack of data showing the flux of CO2 for agricultural practices in developing countries, there is a great need to apply experimental methodologies to address this deficiency. Research was conducted using Bowen Ratio Energy Balance (BREB) instrumentation to quantify the energy balance and CO2 flux of agricultural practices in Lesotho and Zimbabwe. BREB micrometeorological systems were set up to compare and contrast tillage versus no-till practices and the effects of cover crops. The results demonstrated that with a vigilant approach, BREB micrometeorology provides real time measurements of CO2 flux that can measure and distinguish the differences between agricultural practices in southern Africa. The results generally confirmed that two of the major tenants of Conservation Agriculture i.e., reduced tillage (specifically no-till) and cover crops, sequester carbon more than tillage and fallow practices. Because the role of agriculture’s mitigation potential for climate change is not understood by the wider society, it is critical not only to communicate the results of this research but to raise awareness of the role of Agriculture in addressing two of the biggest problems that humankind will face in the future: feeding a burgeoning human population and preventing catastrophic climate change from record concentrations of atmospheric greenhouse gases. To that end, this thesis also touches on research investigating how to increase awareness and interest in agriculture by college students

Using Micrometeorology to Gauge Agriculture\u27s Potential to Sequester Soil Carbon

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

Bowen Ratio Energy Balance Measurement of Carbon Dioxide (CO2) Fluxes of No-Till and Conventional Tillage Agriculture in Lesotho

Global food demand requires that soils be used intensively for agriculture, but how these soils are managed greatly impacts soil fluxes of carbon dioxide (CO2). Soil management practices can cause carbon to be either sequestered or emitted, with corresponding uncertain influence on atmospheric CO2 concentrations. The situation is further complicated by the lack of CO2 flux measurements for African subsistence farms. For widespread application in remote areas, a simple experimental methodology is desired. As a first step, the present study investigated the use of Bowen Ratio Energy Balance (BREB) instrumentation to measure the energy balance and CO2 fluxes of two contrasting crop management systems, till and no-till, in the lowlands within the mountains of Lesotho. Two BREB micrometeorological systems were established on 100-m by 100-m sites, both planted with maize (Zea mays) but under either conventional (plow, disk-disk) or no-till soil mangement systems. The results demonstrate that with careful maintenance of the instruments by appropriately trained local personnel, the BREB approach offers substantial benefits in measuring real time changes in agroecosystem CO2 flux. The periods where the two treatments could be compared indicated greater CO2 sequestration over the no-till treatments during both the growing and non-growing seasons