RESUMEN
Swine manure is kept in outdoor storage facilities until it is applied to cropland. Anaerobic conditions facilitate microbial methane (CH4 ) production at a rate that depends on temperature. Manure CH4 emissions can be the largest contributor to the carbon footprint of pork production. Despite the importance of CH4 , its actual emissions in cold temperate climates are highly uncertain. This study measured emissions from a single-cell earthen manure storage facility at a commercial swine farm near Brandon, Manitoba, Canada, for 3 yr. Complimentary laboratory measurements were done to assess CH4 potential (B0 ). The manure storage regularly received manure from the barn and was only emptied in October. In the summer, manure temperature was usually lower than the air temperature, with the manure temperature (averaged across depths) warming to between 15 and 18.5 °C for only 9 wk. Emissions of CH4 were low, with the CH4 conversion factor being between 3.0 and 11.0%, depending on the year (using the IPCC 2019 default B0 ). Scaled by the number of swine reaching market weight (125 kg) each year, CH4 emissions were between 250 and 902 g CH4 animal-1 . Laboratory measurements of CH4 production potential scaled by VS were 335 ml CH4 g-1 VS at 37 °C, perhaps lower than the IPCC 2019 default value due to barley (Hordeum vulgare L.) in the ration and degradation in the under-barn pit prior to transfer outdoors. Taken together, the low manure temperatures, short warm season, and barley in the ration suggest that emissions from swine manure in cold climates like western Canada are considerably lower than previously estimated based on default factors.
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Gases de Efecto Invernadero , Estiércol , Animales , Granjas , Metano/análisis , Porcinos , TemperaturaRESUMEN
It is uncertain whether process-based models are currently capable of simulating the complex soil, plant, climate, manure management interactions that influence soil nitrous oxide (N2O) emissions from perennial cropping systems. The objectives of this study were (1) to calibrate and evaluate the DeNitrification DeComposition (DNDC) model using multi-year datasets of measured nitrous oxide (N2O) fluxes, soil moisture, soil inorganic nitrogen, biomass and soil temperature from managed grasslands applied with manure slurry in contrasting climates of Canada, and (2) to simulate the impact of different manure management practices on N2O emissions including slurry application i) rates (for both single vs. split); and ii) timing (e.g., early vs. late spring). DNDC showed "fair" to "excellent" performance in simulating biomass (4.7% ≤ normalized root mean square error (NRMSE) ≤ 29.8%; -9.5% ≤ normalized average relative error (NARE) ≤ 16.1%) and "good" performance in simulating soil temperature (13.2% ≤ NRMSE ≤ 18.1%; -0.7% ≤ NARE ≤ 10.8%) across all treatments and sites. However, the model only showed "acceptable" performances in estimating soil water and inorganic N contents which was partially attributed to the limitation of a cascade water sub-model and inaccuracies in simulating root development/uptake. Although, the DNDC model only demonstrated "fair" performance in simulating daily N2O fluxes, it generally captured the impact of the timing and rate of slurry application and soil texture (loam vs. sandy loam) on total N2O emissions. The DNDC model simulated N2O emissions from spring better than split manure application (fall and spring) at the Manitoba site partially due to the overestimation of available substrates for microbial denitrification from fall application during the wet spring periods. Although DNDC performed adequately for simulating most of the manure management impacts considered in this study we recommend improvements in the simulation of soil freeze-thaw cycles, manure decomposition dynamics, soil water storage, rainfall canopy interception, and microbial denitrification and nitrification activities in grasslands.
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Estiércol , Canadá , Fertilizantes , Pradera , Nitrógeno , Óxido Nitroso , SueloRESUMEN
Effective management of dairy manure is important to minimize N losses from cropping systems, maximize profitability, and enhance environmental sustainability. The objectives of this study were (i) to calibrate and validate the DeNitrification-DeComposition (DNDC) model using measurements of silage corn ( L.) biomass, N uptake, soil temperature, tile drain flow, NO leaching, NO emissions, and soil mineral N in eastern Canada, and (ii) to investigate the long-term impacts of manure management under climate variability. The treatments investigated included a zero-fertilizer control, inorganic fertilizer, and dairy manure amendments (raw and digested). The DNDC model overall demonstrated statistically "good" performance when simulating silage corn yield and N uptake based on normalized RMSE (nRMSE) < 10%, index of agreement () > 0.9, and Nash-Sutcliffe efficiency (NSE) > 0.5. In addition, DNDC, with its inclusion of a tile drainage mechanism, demonstrated "good" predictions for cumulative drainage (nRMSE < 20%, > 0.8, and NSE > 0.5). The model did, however, underestimate daily drainage flux during spring thaw for both organic and inorganic amendments. This was attributed to an underestimation of soil temperature and soil water under frequent soil freezing and thawing during the 2013-2014 overwinter period. Long-term simulations under climate variability indicated that spring applied manure resulted in less NO leaching and NO emissions than fall application when manure rates were managed based on crop N requirements. Overall, this study helped highlight the challenges in discerning the short-term climate interactions on fertilizer-induced N losses compared with the long-term dynamics under climate variability.
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Fertilizantes , Zea mays , Agricultura , Canadá , Estiércol , Nitrógeno , Ensilaje , Suelo , AguaRESUMEN
Recent developments in composting technology enable dairy farms to produce their own bedding from composted manure. This management practice alters the fate of carbon and nitrogen; however, there is little data available documenting how gaseous emissions are impacted. This study measured in-situ emissions of methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) from an on-farm solid-liquid separation system followed by continuously-turned plug-flow composting over three seasons. Emissions were measured separately from the continuously-turned compost phase, and the compost-storage phase prior to the compost being used for cattle bedding. Active composting had low emissions of N2O and CH4 with most carbon being emitted as CO2-C and most N emitted as NH3-N. Compost storage had higher CH4 and N2O emissions than the active phase, while NH3 was emitted at a lower rate, and CO2 was similar. Overall, combining both the active composting and storage phases, the mean total emissions were 3.9×10-2gCH4kg-1 raw manure (RM), 11.3gCO2kg-1 RM, 2.5×10-4g N2O kg-1 RM, and 0.13g NH3 kg-1 RM. Emissions with solid-separation and composting were compared to calculated emissions for a traditional (unseparated) liquid manure storage tank. The total greenhouse gas emissions (CH4+N2O) from solid separation, composting, compost storage, and separated liquid storage were reduced substantially on a CO2-equivalent basis compared to traditional liquid storage. Solid-liquid separation and well-managed composting could mitigate overall greenhouse gas emissions; however, an environmental trade off was that NH3 was emitted at higher rates from the continuously turned composter than reported values for traditional storage.
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Contaminantes Atmosféricos/análisis , Amoníaco/análisis , Compostaje/métodos , Industria Lechera , Monitoreo del Ambiente , Dióxido de Carbono/análisis , Granjas , Gases de Efecto Invernadero/análisis , Metano/análisis , Nitrógeno/análisisRESUMEN
Stored liquid dairy manures are methane (CH) emission hotspots because of the large amount of slurry volatile solids (VS) converted into CH by methanogens under anaerobic conditions. Our research has indicated that a reduction of total solids (TS) of slurries before storage can reduce CH emissions. In the current study, methanogen abundance was characterized in tanks with different CH emissions. Using mesoscale slurry storage facilities equipped for continuous gaseous emission monitoring, we stored dairy slurries having TS from 9.5 to 0.3% for up to 6 mo. Samples were taken after Day 30 and Day 120 of the storage (20 May-16 Nov. 2010) from the upper and bottom layers of the slurries. Methanogenic communities were studied by targeting the gene encoding the α subunit methyl-coenzyme M reductase (), which catalyzes the final step of methanogenesis. Interestingly, mean abundances of methanogens increased by â¼8 and 23% at the top and bottom sections, respectively, as slurry TS decreased from 9.5 to 0.3%. Cumulative CH emissions, however, decreased by â¼70% as slurry TS decreased from 9.5 to 0.3%. Nevertheless, compared with Day 30 of storage, mean abundances of methanogens were relatively higher at Day 120 (up to 19%), consistent with an increase in the cumulative CH emissions. Polymerase chain reaction denaturing gel electrophoresis analysis indicated a low methanogen diversity, with most bands sequenced closely related to the genus (>95% amino acid sequence similarity), the hydrogenotrophic methanogens. Results suggest that available carbon substrate and not methanogen abundance may be limiting cumulative CH emissions at reduced TS levels of dairy slurries.
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Archaea , Estiércol/microbiología , Euryarchaeota , Metano/metabolismoRESUMEN
This study was to evaluate the effect of absolute humidity (AH), a combined factor of temperature and relative humidity (RH), on inactivation of avian influenza viruses (AIVs) on surfaces. Suspensions of the H9N2 or H6N2 AIV were deposited onto carrier surfaces that were either porous (pine wood) or non-porous (stainless steel, synthetic rubber and glass). The inoculated carriers were incubated at 23, 35 or 45°C with 25% or 55% RH for up to 28 days. After incubation, virus was recovered and quantified by chicken embryo assays. The time required to obtain a log10 reduction in virus infectivity (D-value) was estimated using a linear regression model. At AH of 5.2 g/m3 (23°C & 25% RH), both viruses survived up to 14 days on the porous surface and for at least 28 days on the non-porous surfaces. The corresponding D-values for H9N2 and H6N2 were 1.49 and 6.90 days on the porous surface and 7.81 and 12.5 days on the non-porous surfaces, respectively. In comparison, at AH of 9.9 g/m3 (35°C & 25% RH) or 11.3 g/m3 (23°C & 55% RH), the D-values for H9N2 and H6N2 dropped to ≤0.76 day on the porous surface and to ≤1.81 days on the non-porous surfaces. As the AH continued to rise from 11.3 to 36.0 g/m3 , the D-value for both viruses decreased further. The relationship between D-value and AH followed a form of y = ax-b for both viruses. The D-values for H9N2 virus were significantly lower (P < 0.05) than those for H6N2 virus. Exposure to ammonia gas at concentrations of 86 and 173 ppm did not significantly alter test results. The findings give evidence that increasing the AH in poultry buildings following an outbreak of disease could greatly reduce the length of time required for their decontamination.
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Virus de la Influenza A/fisiología , Gripe Aviar/virología , Inactivación de Virus , Animales , Embrión de Pollo , Pollos , Elastómeros/química , Vidrio/química , Humedad , Subtipo H9N2 del Virus de la Influenza A/fisiología , Pinus , Porosidad , Acero Inoxidable/química , Propiedades de Superficie , Madera/químicaRESUMEN
Manure remaining in storage due to incomplete removal is a source of microbial inoculum that may affect methane (CH), nitrous oxide (NO), and ammonia (NH) emissions during subsequent storage. Manure removal was studied by loading fresh manure into outdoor concrete tanks (10.6 m) that contained previously stored manure (inoculum) at six levels (0, 5, 10, 15, 20, and 25%, with 0% representing an empty tank). Emissions were continuously measured for 6-mo storage periods (warm and cold seasons) using flow-through chambers. Fluxes during the warm season (average manure temperature at 80 cm depth, = 17°C) were 25 times higher for CH, 20 times higher for NO, and 2.9 times higher for NH compared with the cold season ( = 4°C). Cumulative CH emissions increased linearly with the level of added inoculum in the cold season ( = 0.98). A similar linear increase was observed in the warm season from 0 to 20% inoculum ( = 0.91), after which a decrease in emissions was observed at 25%. Reducing inoculum from 15 to 5% reduced CH emissions by 26% in the warm season and 45% in the cold season. There was no clear effect of inoculum on NO and NH emissions, suggesting that complete manure storage emptying does not alter their emissions.
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Estiércol , Metano/análisis , Óxido Nitroso/análisis , Amoníaco , GasesRESUMEN
This study examined sand filtration as a component of a potato farm wastewater treatment system. Two different sand filter designs, saturated flow and unsaturated flow, were evaluated at three different loading rates: 34, 68, and 136 L m(-2) d(-1). Filter design had a significant effect, with unsaturated flow sand filters having significantly (p < .05) better total suspended solids (TSS) removal (89%) than saturated flow sand filters did (79%). Loading rate also had a significant (p < .05) effect, given that the lowest loading rate had higher mass removal for TSS than the higher loading rates did. Overall, all sand filters removed TSS, 5-d biochemical oxygen demand, and total phosphorus well (62-99%). Total nitrogen removal was twice as high in unsaturated flow filters (53%) than in saturated flow filters (27%), because of the recurring cycle of aerobic and anaerobic conditions during sand saturation and drying in unsaturated flow sand filters.
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Solanum tuberosum , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Agricultura/métodos , Granjas , Filtración , Nitrógeno/análisis , Fósforo/análisis , Dióxido de Silicio , Contaminantes Químicos del Agua/análisis , Contaminación Química del Agua/prevención & controlRESUMEN
Silage effluent is a potent wastewater that can be produced when ensiling crops that have a high moisture content (MC). Silage effluent can cause fish-kills and eutrophication due to its high biochemical oxygen demand (BOD) and nutrient content, respectively. It has a high acidity (pH ≈ 3.5-5) making it corrosive to steel and damaging to concrete, which makes handling, storage and disposal a challenge. Although being recognized as a concentrated wastewater, most research has focused on preventing its production. Despite noted imprecision in effluent production models-and therefore limited ability to predict when effluent will flow-there has been little research aimed at identifying effective reactive management options, such as containment and natural treatment systems. Increasing climate variability and intensifying livestock agriculture are issues that will place a greater importance on developing comprehensive, multi-layered management strategies that include both preventative and reactive measures. This paper reviews important factors governing the production of effluent, approaches to minimize effluent flows as well as treatment and disposal options. The challenges of managing silage effluent are reviewed in the context of its chemical constituents. A multi-faceted approach should be utilized to minimize environmental risks associated with silage effluent. This includes: (i) managing crop moisture content prior to ensiling to reduce effluent production, (ii) ensuring the integrity of silos and effluent storages, and (iii) establishing infrastructure for effluent treatment and disposal. A more thorough investigation of constructed wetlands and vegetated infiltration areas for treating dilute silage effluent is needed. In particular, there should be efforts to improve natural treatment system design criteria by identifying pre-treatment processes and appropriate effluent loading rates. There is also a need for research aimed at understanding the effects of repeated land application of effluent on soil quality and crop yields, as spreading is a common disposal practice.
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Agricultura , Residuos Industriales , Ensilaje , Eliminación de Residuos Líquidos/métodos , Animales , Clima , Productos Agrícolas , Concentración de Iones de Hidrógeno , Ganado , Suelo , Aguas Residuales , Contaminación del Agua/prevención & control , HumedalesRESUMEN
The Canadian dairy sector is a major industry with about 1 million cows. This industry emits about 20% of the total greenhouse gas (GHG) emissions from the main livestock sectors (beef, dairy, swine, and poultry). In 2006, the Canadian dairy herd produced about 7.7 Mt of raw milk, resulting in about 4.4 Mt of dairy products (notably 64% fluid milk and 12% cheese). An integrated cradle-to-gate model (field to processing plant) has been developed to estimate the carbon footprint (CF) of 11 Canadian dairy products. The on-farm part of the model is the Unified Livestock Industry and Crop Emissions Estimation System (ULICEES). It considers all GHG emissions associated with livestock production but, for this study, it was run for the dairy sector specifically. Off-farm GHG emissions were estimated using the Canadian Food Carbon Footprint calculator, (cafoo)(2)-milk. It considers GHG emissions from the farm gate to the exit gate of the processing plants. The CF of the raw milk has been found lower in western provinces [0.93 kg of CO2 equivalents (CO2e)/L of milk] than in eastern provinces (1.12 kg of CO2e/L of milk) because of differences in climate conditions and dairy herd management. Most of the CF estimates of dairy products ranged between 1 and 3 kg of CO2e/kg of product. Three products were, however, significantly higher: cheese (5.3 kg of CO2e/kg), butter (7.3 kg of CO2e/kg), and milk powder (10.1 kg of CO2e/kg). The CF results depend on the milk volume needed, the co-product allocation process (based on milk solids content), and the amount of energy used to manufacture each product. The GHG emissions per kilogram of protein ranged from 13 to 40 kg of CO2e. Two products had higher values: cream and sour cream, at 83 and 78 kg of CO2e/kg, respectively. Finally, the highest CF value was for butter, at about 730 kg of CO2e/kg. This extremely high value is due to the fact that the intensity indicator per kilogram of product is high and that butter is almost exclusively fat. Protein content is often used to compare the CF of products; however, this study demonstrates that the use of a common food component is not suitable as a comparison unit in some cases. Functionality has to be considered too, but it might be insufficient for food product labeling because different reporting units (adapted to a specific food product) will be used, and the resulting confusion could lead consumers to lose confidence in such labeling. Therefore, simple units might not be ideal and a more comprehensive approach will likely have to be developed.
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Huella de Carbono/estadística & datos numéricos , Productos Lácteos/estadística & datos numéricos , Industria Lechera/estadística & datos numéricos , Animales , Canadá , Bovinos , Queso/estadística & datos numéricos , Femenino , Tecnología de Alimentos/estadística & datos numéricos , Efecto Invernadero/estadística & datos numéricos , Leche/estadística & datos numéricos , Modelos Estadísticos , Transportes/estadística & datos numéricosRESUMEN
Agricultural wastewater treatment is important for protecting water quality in rural ecosystems, and constructed wetlands are an effective treatment option. During treatment, however, some C and N are converted to CH(4), N(2)O, respectively, which are potent greenhouse gases (GHGs). The objective of this study was to assess CH(4), N(2)O, and CO(2) emissions from surface flow (SF) and subsurface flow (SSF) constructed wetlands. Six constructed wetlands (three SF and three SSF; 6.6 m(2) each) were loaded with dairy wastewater in Truro, Nova Scotia, Canada. From August 2005 through September 2006, GHG fluxes were measured continuously using transparent steady-state chambers that encompassed the entire wetlands. Flux densities of all gases were significantly (p < 0.01) different between SF and SSF wetlands changed significantly with time. Overall, SF wetlands had significantly (p < 0.01) higher emissions of CH(4) N(2)O than SSF wetlands and therefore had 180% higher total GHG emissions. The ratio of N(2)O to CH(4) emissions (CO(2)-equivalent) was nearly 1:1 in both wetland types. Emissions of CH(4)-C as a percentage of C removal varied seasonally from 0.2 to 27% were 2 to 3x higher in SF than SSF wetlands. The ratio of N(2)O-N emitted to N removed was between 0.1 and 1.6%, and the difference between wetland types was inconsistent. Thus, N(2)O emissions had a similar contribution to N removal in both wetland types, but SSF wetlands emitted less CH(4) while removing more C from the wastewater than SF wetlands.
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Aire/análisis , Dióxido de Carbono/análisis , Metano/análisis , Óxido Nitroso/análisis , Eliminación de Residuos Líquidos , Contaminación del Aire/análisis , Carbono/aislamiento & purificación , Industria Lechera , Monitoreo del Ambiente , Efecto Invernadero , Nitrógeno/aislamiento & purificación , Plantas , Aguas del Alcantarillado , Temperatura , Factores de Tiempo , HumedalesRESUMEN
Agricultural wastewater treatment is important for maintaining water quality, and constructed wetlands (CW) can be an effective treatment option. However, some of the N that is removed during treatment can be volatilized to the atmosphere as ammonia (NH(3)). This removal pathway is not preferred because it negatively impacts air quality. The objective of this study was to assess NH(3) volatilization from surface flow (SF) and subsurface flow (SSF) CWs. Six CWs (3 SF and 3 SSF; 6.6 m(2) each) were loaded with dairy wastewater ( approximately 300 mg L(-1) total ammoniacal nitrogen, TAN = NH(3)-N + NH(4)(+)-N) in Nova Scotia, Canada. From June through September 2006, volatilization of NH(3) during 12 or 24 h periods was measured using steady-state chambers. No differences (p > 0.1) between daytime and nighttime fluxes were observed, presumably due in part to the constant airflow inside the chambers. Changes in emission rates and variability within and between wetland types coincided with changes in the vegetative canopy (Typha latifolia L.) and temperature. In SSF wetlands, the headspace depth also appeared to affect emissions. Overall, NH(3) emissions from SF wetlands were significantly higher than from SSF wetlands. The maximum flux densities were 974 and 289 mg NH(3)-N m(-2) d(-1) for SF and SSF wetlands, respectively. Both wetland types had similar TAN mass removal. On average, volatilization contributed 9 to 44% of TAN removal in SF and 1 to 18% in SSF wetlands. Results suggest volatilization plays a larger role in N removal from SF wetlands.