Conservation agriculture as a climate change mitigation strategy in Zimbabwe

Authors: O'DELL, DEB - University Of Tennessee; EASH, NEAL - University Of Tennessee; HICKS, BRUCE - University Of Tennessee; OETTING, JOEL - University Of Tennessee; Sauer, Thomas; LAMBERT, DAYTON - Oklahoma State University; THIERFELDER, CHRISTIAN - International Maize & Wheat Improvement Center (CIMMYT); MUONI, TARIRAI - Swedish University Of Agricultural Sciences; LOGAN, JOANNE - University Of Tennessee; ZAHN, JAMES - Dupont Tate & Lyle Bio Products Company; GODDARD, JOHN - University Of Tennessee

Submitted to: International Journal of Agricultural Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2020
Publication Date: 4/17/2020
Citation: O'Dell, D., Eash, N.S., Hicks, B.B., Oetting, J.N., Sauer, T.J., Lambert, D.M., Thierfelder, C., Muoni, T., Logan, J., Zahn, J.A., Goddard, J.J. 2020. Conservation agriculture as a climate change mitigation strategy in Zimbabwe. International Journal of Agricultural Sustainability. 18(3):250-265. https://doi.org/10.1080/14735903.2020.1750254.
DOI: https://doi.org/10.1080/14735903.2020.1750254

Interpretive Summary: The exchange of carbon as carbon dioxide is important with respect to greenhouse gas production and soil organic matter. Some of the carbon dioxide taken up by plants during photosynthesis becomes soil organic matter after the plant dies and decays. Conservation agriculture is a crop production practice that promotes reducing soil disturbance, keeping the soil covered by crop residue or a cover crop, and rotating different crops on the same land. These practices are thought to promote soil organic matter accumulation and more sustainable cropping. In this study carbon dioxide exchange was measured for different conservation agriculture systems and compared with conventional practices and fallow. The results show that the conservation agriculture systems had lower carbon dioxide emissions, providing an opportunity to improve soil quality. These results are of interest to practitioners in developing countries with interest in promoting conservation agriculture to enhance crop production and restore degraded soils.

Technical Abstract: There is a need to quantify agriculture’s potential to sequester carbon (C) to inform global approaches aimed at mitigating climate change effects. Many factors including climate, crop, soil management practices, and soil type can influence the contribution of agriculture to the global carbon cycle. The objective of this study was to investigate the C sequestration potential of conservation agriculture (CA) (defined by minimal soil disturbance, maintaining permanent soil cover, and crop rotations). This study used micrometeorological methods to measure carbon dioxide (CO2) flux from several alternative CA practices in Harare, central Zimbabwe. Micrometeorological methods can detect differences in total CO2 emissions of agricultural management practices; our results show that CA practices produce less CO2 emissions. Over three years of measurement, the mean and standard error (SE) of CO2 emissions for the plot with the most consistent CA practices was 0.564 ± 0.0122 g CO2 m-2 h-1, significantly less than 0.928 ± 0.00859 g CO2 m-2 h-1 for the conventional tillage practice. Overall CA practices of no-till with the use of cover crops produced fewer CO2 emissions than conventional tillage or fallow.