For instance, the National Air Emissions Monitoring Study (NAEMS) study, which the National Milk Producers Federation commissioned with the U.S. Environmental Protection Agency, came up with significantly different findings, Wang said.
“NAEMS was conducted from 2007 to 2009 at seven different dairy production facilities located in New York, Indiana, Texas, Wisconsin, California and Washington. The study is a credible representation of ammonia emissions from U.S. dairy farms,” Wang said.
According to the NAEMS study, the average ammonia emissions per cow per day are approximately 60.9 grams. To convert this to metric tons and compare it to the Geophysical Research Letters study:
- 60.9 grams per cow per day multiplied by the 298,000 cows referenced in Geophysical Research Letters article equals 18,148,200 grams per day, which is about 18 metric tons per day. This is significantly less than the 33 to 176 metric tons per day range cited in that study.
- And, if there are only 100,000 cows, the final number would be one-third of that, or 6 metric tons.