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Enhancing movement options for confined dairy cows, like in tie-stall housing, may boost natural behaviour and welfare. Yet, limited data exists on the environmental impact of both indoor and outdoor exercise areas. This study investigates the impact of exercise pen type on effluent properties and gas emissions during winter and/or summer conditions in a northern country such as Canada. Forty-five Holstein dairy cows were randomly assigned to three treatments: (1) no exercise [cows kept indoors with tie-stalls (TSs)]; (2) indoor exercise [access to a 28 m2 cow−1 indoor pen (IP) for 1.5 h d−1] and (3) outdoor exercise [access to a 28 m2 cow−1 outside nonaerated (OnAP) or aerated stand-off pad (OAP) for 1.5 h d−1]. The effluent composition of OnAP and OAP varied notably between seasons. In winter, OAP leachates showed higher biological oxygen demand (+89 %), pH (+1.2 units), ammonium (+96 %) and total solids (+50 %), lower faecal but higher total coliforms (−120 % and +20 %, respectively) than OnAP during summer. In addition, OAP presented higher biological and chemical oxygen demand (+80 %) than OnAP in both seasons. Both OAP and OnAP showed higher carbon dioxide emissions (+150 %) and lower methane emissions during summer (−200 %) than IP and TS. Nitrous oxide emissions were higher for OnAP (+600 %) than in OAP, IP and TS, with no changes in ammonia emissions across treatments. Outdoor exercise for dairy cows using a filtering pen didn't meet environmental limits for removing leached contaminants. Exercise pens raised carbon dioxide and nitrous oxide emissions but decreased methane emissions. • Non-aerated, aerated pads served as seasonal exercise areas for tie-stall cows. • Efficient woodchip matrix filters pad leachates by removing contaminants. • Aeration failed to enhance leachate contaminant removal in the stand-off pad. • Outside exercise pens reduce greenhouse gas emissions from dairy housing surfaces. [ABSTRACT FROM AUTHOR]

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]

Background and aims: Approximately 50 % of belowground organic carbon is present in the northern permafrost region and due to changes in climate there are concerns that this carbon will be rapidly released to the atmosphere. The release of carbon in arctic soils is thought to be intimately linked to the N cycle through the N cycle's influence on microbial activity. The majority of new N input into arctic systems occurs through N-fixation; therefore, N-fixation may be the key driver of greenhouse gases from these ecosystems. Methods: At Alexandra Fjord lowland, Ellesmere Island, Canada concurrent measurements of N-fixation, N mineralization and nitrification rates, dissolved organic soil N (DON) and C, inorganic soil N and surface greenhouse gas fluxes (CO, NO and CH) were taken in two ecosystem types (Wet Sedge Meadow and Dryas Heath) over the 2009 growing season (June-August). Using Structural Equation Modelling we evaluated the hypothesis that CO, CH and NO flux are linked to N-fixation via the N cycle. Results: The soil N cycle was linked to CO flux in the Dryas Heath ecosystem via DON concentrations, but there was no link between the soil N cycle and CO flux in the Wet Sedge Meadow. Methane flux was also not linked to the soil N cycle, nor surface soil temperature or moisture in either ecosystem. The soil N cycle was closely linked to NO emissions but via nitrification in the Wet Sedge Meadow and inorganic N in the Dryas Heath, indicating the important role of nitrification in net NO flux from arctic ecosystems. Conclusions: Our results should be interpreted with caution given the high variability in both the rates of the N cycling processes and greenhouse gas flux found in both ecosystems over the growing season. However, while N-fixation and other N cycling processes may play a more limited role in instantaneous CO emissions, these processes clearly play an important role in controlling NO emissions. [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]