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Canada has targeted a 30% reduction in N 2 O emissions from fertilizer by 2030 in its commitments to reduce greenhouse gas emissions. To help achieve these commitments, a 'Pipes & Valves' conceptual visualization of the DNDC model was combined with the DeNitrification-DeComposition (DNDC) model to evaluate a suite of nutrient management and conservation practices. The objectives were to meet the 30% reduction targets in N 2 O emissions as well as other reactive-N species (N 2 O, NH 3 and NO 3 - leaching) to provide a systems approach while increasing corn yields. This was accomplished by: 1) developing a 'Pipes & Valves' conceptual visualization model; 2) evaluating a full system DNDC model with 3-years of NH 3 volatilization, N 2 O emission, inorganic N, crop yield and N uptake data; 3) applying the 'Pipes & Valves' DNDC system to identify N-management strategies that mitigate N-loss and improve yields. The DNDC model compared simulated and measured N-loss and crop performance over 3 years for N- management practices including pre-plant versus side-dress UAN injection with either no inhibitors, a urease inhibitor or a dual urease and nitrification inhibitor. A Pipe and Valves conceptual visualization model was developed and used with the DNDC model to simulate 14 management scenarios based on moldboard plow tillage versus conservation tillage, and fertilizer management including fertilizer type (urea vs. urea ammonium nitrate, UAN), inhibitor (none, nitrification inhibitor, urease inhibitor or both), placement (broadcast vs. injection), timing (at planting vs. split application), and N rate (recommended vs. 15% reduction). The DNDC model was evaluated using field data and had excellent performance for yields, cumulative N 2 O emissions and soil temperature while soil water predictions were fair using standard performance metrics. Multiple nutrient management and/or conservation tillage practices decreased NH 3 losses by 36–96% compared to broadcast urea. A pre-plant broadcast urea and nitrification inhibitor treatment and a conservation tillage treatment with side-dressed injected UAN with a dual urease and nitrification inhibitor reduced N 2 O losses by 37-40%. Although several management practices reduced one N-loss pathway by ≥ 30%, only side-dress injected UAN with urease plus nitrification inhibitors under conservation tillage achieved multiple reductions of 40%, 93% and 62% in N 2 O, NH 3 and reactive-N, respectively while increasing corn grain yields by 7%. Combining the 'Pipes & Valves' conceptual visualization model with DNDC modelling was effective for determining how 4R nutrient management and conservation tillage can be stacked and used worldwide to meet N-loss reduction targets without compromising yields. • The DeNitrification DeCompositon (DNDC) model successfully predicted corn yield & nitrogen losses. • The Pipes & Valves conceptual visualization model will help mitigate N losses to air and water. • DNDC identified management practices that can reduce N 2 O, NH 3 and reactive-N by ≥30%. • Crop yields can increase by ≥ 10% using nutrient management & conservation practices. • The Pipes & Valves and DNDC model are tools to help reduce world-wide fertilizer N-loss. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural soils are a significant anthropogenic source of nitrous oxide (N2O) to the atmosphere. Despite likely having large emissions of N2O, there are no continuous multi-year studies of emissions from poorly drained floodplain soil. In the present study, the micrometeorological flux of N2O (F N ) was measured over three years (2006–2008) in a maize (Zea mays L.)/faba (Vicia faba minor L.)/spring-wheat (Triticum aestivum L.) rotation in the Red River Valley, Manitoba, Canada on a gleyed humic verticol soil. Comparison of newly established reduced and intensive tillage treatments showed no difference in F N within the constraints of the high variability between duplicate plots. The annual gap-filled ΣF N across tillage treatments was 5.5, 1.4, and 4.3kgNha−1 in the maize, faba, and spring-wheat crop years, respectively. Emissions from fertilizer N addition and soil thaw the following spring was responsible for the greater ΣF N in the maize and spring-wheat years. Using four approaches to approximate background ΣF N resulted in estimates of 3.5–3.8% and 1.4–1.8% of applied fertilizer N emitted as N2O for the maize and spring-wheat crops, respectively. The CO2 global warming potential equivalent of ΣF N over the three study years was an emission of 5.4MgCO2-equiv.ha−1 which adds to the previously determined C balance emission of 11.6MgCO2-equiv.ha−1. [Copyright &y& Elsevier]

This paper summarizes greenhouse gas (GHG) emissions measurements obtained during several recent studies conducted by Environment Canada, Emissions Research and Measurement Division (ERMD). A variety of heavy-duty vehicles and engines operating on a range of different fuels including diesel, biodiesel, compressed natural gas (CNG), hythane (20% hydrogen, 80% CNG), and liquefied natural gas (LNG), and with different advanced aftertreatment technologies were studied by chassis dynamometer testing, engine dynamometer testing or on-road testing. Distance-based emission rates of CO2, CH4, and N2O are reported. Fuel consumption calculated by carbon balance from measured emissions is also reported. The measurement results show, for heavy-duty diesel vehicles without aftertreatment, that while CO2 emissions dominate, CH4 emissions account for between 0% and 0.11% and N2O emissions account for between 0.16% and 0.27% of the CO2-equivalent GHG emissions. Both of the aftertreatment technologies (diesel oxidation catalyst and active regeneration diesel particle filter) studied increased N2O emissions compared to engine out emissions while CH4 emissions remain essentially unchanged. No effect on tailpipe GHG emissions was found with the use of up to 20% biodiesel when the engine was equipped with an oxidation catalyst. Biodiesel use did show some reductions in tailpipe GHG emissions as compared to ULSD without aftertreatment and with the use of a diesel particle filter. Natural gas and hythane also offer decreased GHG emissions (10–20%) at the tailpipe when compared with diesel. Emission factors (gL−1 fuel) for CH4 and N2O are suggested for heavy-duty vehicles fueled with diesel-based fuels and natural gas. These emission factors are substantially lower than those recommended for use by IPCC methodologies for developing national inventories. [Copyright &y& Elsevier]