Dairy Farm Methane Emissions Using a Dispersion Model
- S. M. McGinn *a and
- K. A. Beauchemina
There is a need to know whole-farm methane (CH4) emissions since confined animal facilities such as beef cattle feedlots and dairy farms are emission “hot spots” in the landscape. However, measurements of whole-farm CH4 emissions can differ between farms because of differences in contributing sources such as manure handling, number of lactating and nonlactating cows, and diet. Such differences may limit the usefulness of whole-farm emissions for national inventories and mitigation purposes unless the variance between farms is taken into account or a large number of farms can be examined. Our study describes the application of a dispersion model used in conjunction with field measurements of CH4 concentration and stability of the air to calculate whole-farm emissions of CH4 from three dairy farms in Alberta, Canada, during three sequential campaigns conducted in November 2004 and May and July 2005. The dairy farms ranged in herd size from 208 to 351 cows (102 to 196 lactating cows) and had different manure handling operations. The results indicate that the average CH4 emission per cow (mixture of lactating and nonlactating) from the three dairy farms was 336 g d−1, which was reduced to 271 g d−1 when the emission (estimated) from the manure storage was removed. Further separation of source strength yielded an average CH4 (enteric) emission of 363 g d−1 for a lactating cow. The estimated CH4 emission intensities were approximately 15 g CH4 kg−1 dry matter intake and 16.7 L CH4 L−1 of milk produced. The approach of understanding the farm-to-farm differences in CH4 emissions as affected by diet, animal type, and manure management is essential when utilizing whole-farm emission measurements for mitigation and inventory applications.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. . Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.