Location: Soil Management and Sugarbeet ResearchTitle: Deficit irrigation reduces absolute, but not yield-scaled greenhouse gas emissions
Submitted to: Soil Ecology Society Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2019
Publication Date: 5/28/2019
Citation: Flynn, N.E., Stewart, C.E., Comas, L.H., Fonte, S. 2019. Deficit irrigation reduces absolute, but not yield-scaled greenhouse gas emissions. Soil Ecology Society Conference. 2019 May 29-31;Toledo, OH.
Technical Abstract: The pressure of rising global food demand in combination with increasingly limited water and land resources requires the development of farm management practices that improve water productivity and contribute to farmers’ capacity to adapt to a changing climate. Strategic deficit irrigation (SDI) aims to reduce crop water usage with minimal impacts on crop yield, and may have important implications for climate change mitigation. We tested SDI practices in a replicated corn field trial near Greeley, Colorado. Three treatments were applied based on target percent of maximum crop evapotranspiration (ET) during key growth stages. Greenhouse gas (GHG) fluxes of nitrous oxide (N2O) and carbon dioxide (CO2) emissions were assessed on a regular basis during the growing season. In comparison to the 100% ET treatment, cumulative N2O-N emissions were reduced by 15 and 40% in the 65% ET and 40% ET treatments respectively. Cumulative CO2-C emission were reduced by 7 and 22% in the 65%ET and 40% ET treatments respectively. Soil temperature was a significant driver of both N2O and CO2 fluxes. Reduced surface moisture conditions under DI can reduce GHG emissions but also have a significant impact on yield. While the 100% ET treatment had the highest absolute emissions, it also had lower yield-scaled global warming potential in comparison to the deficit irrigation treatments. These results suggest that while SDI is effective at reducing water use and GHG emissions from agriculture, yield should be considered when assessing SDI as a climate-smart solution.