Measuring Emissions of Volatile Organic Compounds from Silage

Authors: Montes, Felipe; Hafner, Sasha; Rotz, Clarence - Al

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 7/21/2009
Publication Date: 7/24/2009
Citation: Montes, F., Hafner, S.D., Rotz, C.A. 2009. Measuring Emissions of Volatile Organic Compounds from Silage. Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE). Paper No. 096184.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: Volatile organic compound (VOC) emissions are considered to be important precursors to smog and ozone production. An experimental protocol was developed to obtain undisturbed silage samples from silage storages. Samples were placed in a wind tunnel where temperature, humidity, and air flow were controlled to measure their influence on VOC emission rates from silage surfaces. Measurements of ethanol, methanol, and acetic acid emissions under these controlled laboratory conditions showed a characteristic pattern where emissions were high immediately after fresh silage was exposed to circulating air, declined rapidly over the next 2 h, and then slowly declined over a period of 24 h. A change in temperature from 5deg C to 20 deg C caused up to a fourfold increase in emission rate and the magnitude of this increase was different among the three compounds. The speed of air moving over the silage had important effects on VOC emission rate, cumulative emissions, and the pattern of emissions through time. VOC emissions from corn, mixed grass-legume, and alfalfa silages were very different. Ethanol emissions were highest from corn silage, followed by mixed grass-legume and alfalfa. Eight-hour cumulative methanol emissions were as high as 39 g/m**2 from mixed grass-legume silage. These results have important implications for accurate field measurement of VOC emissions from silage.