| 1. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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Effects of animal activity and air temperature on methane and ammonia emissions from a naturally ventilated building for dairy cows
- 2011
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 45, s. 6760-6768
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of how different factors affect gas emissions from animal buildings can be useful for emission prediction purposes and for the improvement of emission abatement techniques. In this study, the effects of dairy cow activity and indoor air temperature on gas emissions were examined. The concentrations of CH(4), NH(3), CO(2) and N(2)O inside and outside a dairy cow building were measured continuously between February and May together with animal activity and air temperature. The building was naturally ventilated and had a solid concrete floor which sloped towards a central urine gutter. Manure was scraped from the floor once every hour in the daytime and once every second hour at night into a partly covered indoor pit which was emptied daily at 6 a.m. and at 5 p.m. Gas emissions were calculated from the measured gas concentrations and ventilation rates estimated by the CO(2) balance method. The animal activity and emission rates of CH(4) and NH(3) showed significant diurnal variations with two peaks which were probably related to the feeding routine. On an average day, CH(4) emissions ranged from 7 to 15 g LU(-1) h(-1) and NH(3) emissions ranged from 0.4 to 1.5 g LU(-1) h(-1) (1 LU = 500 kg animal weight). Mean emissions of CH(4) and NH(3) were 10.8 g LU(-1) h(-1) and 0.81 g LU(-1) h(-1), respectively. The NH(3) emissions were comparable to emissions from tied stall buildings and represented a 4% loss in manure nitrogen. At moderate levels, temperature seems to affect the behaviour of dairy cows and in this study where the daily indoor air temperature ranged from about 5 up to about 20 degrees C, the daily activity of the cows decreased with increasing indoor air temperature (r = -0.78). Results suggest that enteric fermentation is the main source of CH(4) emissions from systems of the type in this study, while NH(3) is mainly emitted from the manure. Daily CH(4) emissions increased significantly with the activity of the cows (r = 0.61) while daily NH(3) emissions increased significantly with the indoor air temperatures (r = 0.66). Daily CH(4) emissions were negatively correlated to the indoor air temperature (r = -0.84). This suggests that increased daily indoor air temperatures due to seasonal changes may bring about decreased animal activity which may decrease the release of CH(4) from dairy cows. Finally, changes in daily NH(3) emissions were influenced more by the indoor air temperature than by the activity of the cows. (C) 2011 Elsevier Ltd. All rights reserved.
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| 2. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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EFFECTS OF ANIMAL AND CLIMATE PARAMETERS ON GAS EMISSIONS FROM A BARN FOR FATTENING PIGS
- 2011
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Ingår i: Applied Engineering in Agriculture. - : American Society of Agricultural and Biological Engineers (ASABE). - 0883-8542 .- 1943-7838. ; 27, s. 1027-1037
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Tidskriftsartikel (refereegranskat)abstract
- Increased knowledge of the factors that affect emissions from livestock barns may lead to a better understanding of daily (between different days) and diurnal (within a specific day) variations in emissions, an improvement of mitigation methods and a refinement of emission models. The influence of animal activity, animal weight, indoor air temperature and relative humidity on carbon dioxide, methane, and ammonia emissions was assessed on a daily and diurnal basis in a barn with three successive batches of fattening pigs. The floor was partly slatted, manure was removed daily, and the ventilation rate was fixed for each batch. Variations between the batches in mean methane emissions (0.33-1.62 g pig(-1) h(-1)) were larger than the variations in the mean emissions of carbon dioxide (84-91 g pig(-1) h(-1)) and ammonia (0.18-0.20 g pig(-1) h(-1)). Animal weight explained most of the daily variations in carbon dioxide and ammonia emissions. Animal weight and indoor air temperature explained most of the daily variations in methane emissions. A regression analysis of methane emissions as a function of the indoor air temperature and animal weight explained 56% of the variations in the measured methane emissions. Animal activity decreased with increasing animal weight and air temperature. Diurnal variations in carbon dioxide and ammonia emissions were mainly affected by the animal activity, with correlation coefficients (r) of 0.89 and 0.68, respectively. Diurnal variations in methane emissions only slightly correlated with the animal activity (r = 0.41, p = 0.05). Emission variations emphasized the need for measurements during different times within the day and during the growing period in order to obtain reliable data for assessing abatement techniques.
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| 3. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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Effects of wood shavings addition and different climatic conditions on ammonia and odour emissions from fresh animal manure
- 2010
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The addition of wood shavings and changing the climatic conditions as methods of mitigating ammonia and odour emissions were investigated using fresh pig and cow manure samples. The manure from each animal type was separated into two portions and wood shavings were mixed with one portion. Emissions from identical quantities of manure with and without wood shavings were measured in a flux chamber. The manure temperature was varied between 15 and 30 ºC. Fresh air at temperatures between 15 and 25 ºC was passed at a fixed rate over the manure in the chamber. Gas and odour concentrations were measured using a photoacoustic multigas analyser 1412 (Lumasense Technologies A/S) and an olfactometer respectively. The addition of wood shavings decreased the total-N and NH4 +-N but increased the ratio between carbon and nitrogen (C/N) as well as the pH. Ammonia emissions increased with manure temperature for both manure types. Odour emissions increased with the cow manure temperature. Odour emissions had a positive tendency with the pig manure temperature for samples without wood shavings. The water vapour pressure was positively correlated to the emissions from the cow manure but not from the pig manure. A clear relationship between ammonia and odour emissions could not be established. The addition of wood shavings lowered the ammonia emissions from the cow manure but not from the pig manure
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| 4. |
- Martin Ngwabie, Ngwa
(författare)
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Gas emissions from dairy cow and fattening pig buildings : effects of animal parameters, climatic factors and manure management on methane and ammonia missions
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this research is to contribute to the knowledge concerning the abatement of gas emissions from livestock production. Investigations regarding the choice of sampling locations for gas concentration measurements, quantification of gas emissions and the factors that affect gas emissions were conducted. NH₃, CH₄, CO₂ and N₂O emissions were measured from two naturally ventilated buildings for dairy cows and from a mechanically ventilated building for fattening pigs. Animal activity, temperature and humidity were also measured. Gas and odour emissions from manure samples with and without the addition of wood shavings were measured in a flux chamber at different air and manure temperatures. Significant differences existed in the mean concentrations of all the gases at various indoor sampling locations in a naturally ventilated building for dairy cows. The differences in gas concentrations between various sampling locations were much smaller for long-term, relative to short-term, measurements, suggesting that a single sampling location during long-term measurements may generate representative data. Decreasing daily animal activity was associated with increasing pig weight, and with increasing air temperatures for the cows. Diurnal variations in gas emissions were related to feeding/cleaning routines and to animal activity. Daily emissions from the pig building increased with pig weight and temperature. Air temperature was more important than cow activity for daily NH₃ emissions while cow activity was more important than air temperatures for daily CH₄ emissions. Reducing manure temperatures and increasing manure carbon-to-nitrogen ratio are potential NH₃ abatement techniques. However, low air temperatures may increase cow activity which may in turn increase CH₄ emissions. Increasing the frequency of manure removal from the floor and from animal buildings reduces indoor emissions of most gases. Low N₂O emissions were measured from the buildings in this study; hence the use of liquid manure systems might reduce N₂O emissions.
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| 5. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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Gaseous emissions from a fattening piggery and a dairy barn with an automatic milking system
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Abstract. The concentrations of CH4, N2O, CO2 and NH3 were measured with a photoacoustic multi-gas analyser 1412 and a multiplexer 1309 (Lumasense Technologies A/S, Ballerup, Denmark) in a piggery over two fattening periods and in a dairy cow barn. The aim was to analyse and compare differences in emissions based on seasonal changes, animal species and management systems. The mechanically ventilated piggery was a slurry-based small scale research facility with a partly slatted floor and daily manure removal with scrapers. It housed 50 and 54 fattening pigs per batch in spring and in autumn, respectively. The dairy cow barn was naturally ventilated and had cubicles and a solid sloping floor with a central urine gutter. The floor was scraped once every hour during the daytime and once every two hours at night. It housed 108 Holstein dairy cows, which were milked automatically. The average milk production was 31.5 kg milk cow-1 day-1. The air flow in the piggery was in the range of 55–103 m3 pig-1 h-1. Emissions in the piggery were 2.3–4.9 g CH4 LU-1 h-1 and 1.3–1.6 g NH3 LU-1 h-1 and were influenced by seasonal changes (1 LU = 500 kg animal weight). The air flow in the dairy cow barn was calculated using CO2 mass balance and corrected for cow activity. The average daily air flow was 268–917 m3 LU-1 h-1 with a mean of 524 m3 LU-1 h-1. Emissions in the dairy cow barn were 10.9 g CH4 LU-1 h-1 and 0.82 g NH3 LU-1 h-1. Cow activity correlated with CH4 (R2 = 0.91) and NH3 (R2 = 0.56) emissions, where R2 is the coefficient of determination. Emissions in the dairy cow barn were influenced more by the activity of the cows rather than the ventilation rate, indicating a useful mitigation parameter. Keywords. Livestock buildings, animal activity, ventilation rate, ammonia, greenhouse gases
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| 6. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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Influence of animal activity and weight gain on the ventilation and emission rates of greenhouse gases and ammonia from a fattening pig building in summer
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Variations in CH4, N2O, CO2 and NH3 emissions from livestock may be caused by management routines, changes in animal activity and weight. These were investigated in a mechanically-ventilated, slurry-based pig building with a partly slated floor. The manure channels were emptied between 8–9 a.m. The ventilation rate, which was kept constant, was measured with an anemometer and calculated based on CO2 balance. The difference between both methods increased from 3% at the beginning to 35% at the end of the fattening period. Significant correlations (p < 0.001) existed between the activity and the emission rates of CO2 (r = 0.89), NH3 (r = 0.65) and N2O (r = 0.74), but not for CH4. CO2 and NH3 emissions increased at rates of 18 g CO2 pig-1 d-1 and 82 mg NH3 pig-1 d-1. CH4 emission was dumped-shaped with a maximum at pig weight of about 75 kg
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| 7. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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Influence of environmental factors and the addition of wood shavings on ammonia and odour emissions from fresh livestock manure
- 2010
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Ingår i: Agricultural Engineering International: the CIGR Ejournal. - 1682-1130. ; 12, s. 68-81
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Tidskriftsartikel (refereegranskat)abstract
- Gaseous emissions from livestock manure may adversely affect human and animal health as well as the surrounding environment. In an effort to understand and mitigate these emissions, the effects of different environmental factors and the addition of wood shavings on ammonia and odour emissions from fresh pig and dairy cow manure were studied. The manure was divided into two portions and wood shavings were mixed with one portion. Emissions from equal volumes of both portions were measured at different environmental conditions in a flux chamber. The manure temperature was varied between 15–30 ºC. Fresh air at temperatures between 16–26 ºC was passed at a fixed rate over the manure. The addition of wood shavings decreased the total-N and NH4+-N, but increased the pH of the manure at the end of the experiment. The temperature of the manure with wood shavings increased faster than that of the manure without wood shavings. The ammonia emission from the pig manure (0.08–0.41 mg m-2 s-1) was on average much higher than the ammonia emission from the cow manure (0–0.08 mg m-2 s-1). The odour emission from the pig manure was high (21–930 OU m-2 s-1), and significantly higher than the odour emission from the cow manure (1–6 OU m-2 s-1). A positive correlation was found between the ammonia emissions and the manure temperature. Ammonia emissions were about 2 times higher at manure temperatures of about 25 ºC compared to emissions at about 15 ºC. Odour emissions were positively correlated with the temperature of cow manure. Ammonia emissions at 25 ºC were high, while odour emissions at 25 ºC were lower than those at 20 ºC for the pig manure with wood shavings. The water vapour pressure was positively correlated to the emissions from the cow manure but not from the pig manure. The measurements indicated a positive correlation between ammonia and odour emissions for the cow manure as well as for the pig manure without wood shavings. The addition of wood shavings to animal manure does not seem to automatically mitigate ammonia or odour emissions as it also affects the temperature and the pH
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| 8. |
- Martin Ngwabie, Ngwa, et al.
(författare)
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Multi-location measurements of greenhouse gases and emission rates of methane and ammonia from a naturally-ventilated barn for dairy cows
- 2009
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Ingår i: Biosystems Engineering. - : Elsevier BV. - 1537-5110 .- 1537-5129. ; 103, s. 68-77
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Tidskriftsartikel (refereegranskat)abstract
- The building had 164-195 Holstein dairy cows. The milk production was 31-33 kg cow(-1)d(-1). Manure gutters beneath the partially slatted floor in the building were scraped twice a day. Measurements took place during the winter when the cows were permanently indoors and during 1 week in the spring when the cows were indoors at night and outside grazing during the daytime. The indoor concentrations were measured at nine evenly distributed locations, while outdoor concentrations were measured at two locations. The mean ventilation rate in winter was 250-26S m(3) LU(-1) h(-1) and in spring, it was 401 m(3) LU(-1) h(-1). The emissions of NH3 and CH(4) were in the range of 0.89-1.13 and 9-13 g LU-1 h-1, respectively. A strong positive correlation was found between enhanced CO(2) and CH(4) concentrations. (C) 2009 IAgrE. Published by Elsevier Ltd. All rights reserved.
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