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This study was aimed at evaluating the CO 2 and H 2 O balance methods for estimating the ventilation rate in a naturally ventilated barn for dairy cows during the spring transitional season. Animal activity measured using the DeLaval activity meter system was also studied and the emission factors of CH 4 , N 2 O and NH 3 were generated. Measurements were carried out in a free-stall dairy barn with cubicles. The main barn had a solid concrete floor which was mechanically scraped six times in a day. The activity of the cows showed a distinct diurnal pattern with peaks between 7 and 9 a.m. and also between 6 and 8 p.m. The lowest activity measured at about 5 a.m. was 275% lower than the peak activities. Variations in animal activity were similar to reported patterns suggesting that the DeLaval meter system might provide a high resolution measurement of animal activity and hence ventilation rates based on the CO 2 balance method since all cows are considered. The average ventilation rates were fairly similar (p = 0.08) with means of 502 ± 248 m 3 LU -1 h -1 and 575 ± 258 m 3 LU -1 h -1 for the CO 2 and H 2 O methods respectively (1 LU = 500 kg animal mass). The H 2 O method can provide a reasonable alternative for estimating ventilation rates in dairy cow barns when CO 2 concentration is not measured. The mean emission factors were 12.4 g CH 4 LU -1 h -1 , 0.60 g NH 3 LU -1 h -1 and 40.3 mg N 2 O LU -1 h -1 .

Handling and storage of a variety of types of agricultural wastes results in the formation and release of nitrous oxide (N2O) and methane (CH4) gases to the atmosphere. These gases contribute to climate change through the greenhouse effect. Few studies however have examined evolution of these gases from poultry litter. N2O is a by-product of nitrification and an intermediate product of denitrification, and is often produced when both aerobic and anaerobic conditions are present. CH4 emissions, however, are associated with anaerobic reactions. Outdoor storage of broiler litter provides an excellent media for which both aerobic and anaerobic zones can coexist, particularly when the litter is of varying ages from multiple broiler cycles. It provides a large amount of nitrogen for bacterial nitrification/denitrification processes as well as carbon to support anaerobic bacterial fermentation. The objective of the study was to quantify N2O and CH4 emissions for broiler litter stored in an uncovered outdoor bunker by conducting full-scale field experiments. A modified micrometeorological mass balance approach was used to monitor emissions from stored broiler litter in a three-walled concrete bunker. Air concentrations of N2O and CH4 were measured using tuneable-diode laser spectroscopy. Experiments over the course of approximately 65 days yielded average emission rates of approximately 18µg m-2 s-1 and 75µg m-2 s-1 for nitrous oxide and methane respectively.

Increasing environmental concerns associated with liquid swine manure storage facilities has lead many producers to seek alternative storage techniques. Composting the liquid manure with a high carbon substrate before storage has received increased attention, primarily due its ability to minimize odour, reduce the overall waste volume, and reduce environmental risks associated with application to surrounding agricultural lands. Unfortunately minimal knowledge is available on the production of nitrous oxide (N2O) and methane (CH4), both powerful greenhouse gases, during the composting process. Using an open ‘mega-chamber’ the emissions of N2O and CH4 were recorded, with two Tunable Diode Laser Trace Gas Analysers, TDLTGA, one for N2O and one for CH4, from composting swine manure with cereal straw. The average emission rates were found to be 1056 ng of N2O-N m -2 s -1 and 58.97 mg of CH4 m -2 s -1 , producing a total of 203.614 kg of CO2 equivalents over the 12.8 day composting period from the 26,457 L of composted manure. Extrapolating this data for an entire year, composting all the manure produced on a Southern Ontario hog finishing operation was found to reduce N2O and CH4 emissions, expressed as CO2 equivalents, to 15 and 24% of the IPCC tier 1 and tier 2 emissions values for liquid manure storage, respectively.