Open Collections

Cao, Ming

University of British Columbia

While greenhouse gases (GHGs) naturally exist in terrestrial ecosystems and the atmosphere, concentrations have risen as a result of industrial development and human activities. This study investigated soil-derived GHG fluxes and soil water dynamics under climate-smart agricultural interventions from April to October 2023, at an organic farm in the Lower Mainland of British Columbia, Canada. In a randomized block design and a land cover succession of cover crop (various) to bare soil to Brassica spp., key parameters including soil GHG fluxes and soil moisture (soil volumetric water content, soil matric potential) were monitored using automated closed-chamber systems and soil water sensors. The soil treatments were: 1) soil amendments targeting high nitrogen mineralization with vetch-rye clover polyculture cover crops; 2) soil amendments targeting high nitrogen mineralization with rye clover cover crops; 3) no soil amendments with vetch-rye clover polyculture cover crops; 4) control treatment with no soil amendments nor cover crops. Other environmental variables such as weather and vegetation status were obtained from a nearby weather station and via satellite imagery, respectively. Within the purview of the analyses, soil moisture was found to be the most important factor for explaining soil GHG variations, especially for CH₄. Overall, the study area emitted CO₄ and N₂O, and showed weak CH₄ uptake by the soil. Average fluxes of CH₄ and N₂O were found to be relatively low compared to studies done in other parts of the world. Treatment effects on soil GHG fluxes were the lowest when no nutrient amendments or cover crops were applied. There was also evidence that transient GHG phenomena, such as N₂O bursts, could be observed within short timeframes but were masked when averaging over longer timeframes. By calculating the global warming potential (GWP) for each GHG, it was found that CO₂ constantly dominated the GWP across the studied time. The temporal interaction of soil GHG fluxes with soil moisture during wetting and drying cycles was nuanced, as some lagged responses of soil GHG changes to changing soil moisture conditions were observed. The study's results offer insights for local farming adaptation to prioritize resources for reducing CO₂ emissions.

Text

2024-08-29

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89077

Resources, Environment and Sustainability

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/