Nitrous Oxide Emission Reduction in an Annual Cropping System as a function of Nitrification Inhibitors and Liquid Manure Injection Timings

  • Author / Creator
    Lin, Sisi
  • Nitrous oxide (N2O) contributes to global warming and ozone depletion. Two-thirds of the global N2O emissions are derived from agricultural soils receiving manure or fertilizer applications. The goal of this study was to identify and develop management practices that can decrease N2O emissions from manured soils. We tested two times of liquid manure injections (early fall versus late spring) and two nitrification inhibitors (NIs; nitrapyrin vs. DMPP). We conducted two field experiments in central Alberta (Lacombe and Edmonton), Canada over a period of 13 months and a 28-day laboratory incubation. Barley (Hordeum vulgare L.) for silage was planted, and productivity and N uptake were recorded. Soil ammonium and nitrate concentrations and N2O fluxes were repeatedly monitored. First-order kinetic models represented well mineral N transformations in both field and incubation experiments, with the exception of fast nitrate depletion rates which were better depicted by second-order models. Compared to the controls, field N2O emissions were increased by manure application (on average 3.15 vs. 0.48 kg N ha-1 yr-1 at both sites), but emissions were sharply reduced with NIs. For instance, in our Lacombe site, fall manure treated with DMPP reduced annual N2O emissions by 81%, and nitrapyrin reduced emissions by 58%. The emission reductions caused by NIs were also evident in the spring manure field treatments, our incubation, and at our Edmonton site, but the reductions were in general smaller possibly due to prevailing drier conditions - in particular during mid spring in Edmonton. Compared to the spring manure timing, fall manure without NIs resulted in an approximate two-fold increase in N2O emissions, due to major peak fluxes following the early spring snow-melt, which accounted for at least 65% of the annual N2O emissions. Fall manure timing also reduced plant productivity and N uptake. In summary, spring-applied manure with NIs can mitigate N2O emissions in Alberta’s agriculture and in regions with comparable agro-ecological conditions. 

  • Subjects / Keywords
  • Graduation date
    Fall 2016
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.