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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #308747

Title: Lab-assay for estimating methane emissions from deep-pit manure storages

Author
item ANDERSON, DANIEL - Iowa State University
item VAN WEELDEN, MARK - Iowa State University
item Trabue, Steven - Steve
item PEPPLE, L - University Of Illinois

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2015
Publication Date: 8/15/2015
Publication URL: https://handle.nal.usda.gov/10113/5463324
Citation: Anderson, D., Van Weelden, M.B., Trabue, S.L., Peeple, L.M. 2015. Lab-assay for estimating methane emissions from deep-pit manure storages. Journal of Environmental Management. 159:18-26.

Interpretive Summary: Methane emission is an important part of the evaluation of animal manure management systems. Field procedures used for estimating methane emission rates require expensive equipment, are time consuming, and require large staff. Emission estimates from these studies are highly variable over time and between farms. Consequently, large numbers of studies must be conducted to develop understanding of variations. The purpose of this report is to develop a quick laboratory method that mimics field conditions. Key parts of the method are determining how fast methane is produced from the manure, recording the field temperature, and measuring or estimating the depth of the manure layer. Methane production is measured over a three-day period for whole manure that is incubated at room temperature. The result of the method shows good agreement between literature values and values generated in this study. The results from this method predict an average methane emission factor on a per animal basis and methane emission rates similar to other studies using more extensive testing and monitoring of swine operations. Information in this report will be of value for growers, engineers, and regulatory officials when determining methane emission from swine production facilities at a fraction of the cost of traditional whole facility monitoring.

Technical Abstract: Methane emission is an important element in the evaluation of manure management systems due to the potential impact it has on global climate change. Field procedures used for estimating methane emission rates require expensive equipment, are time consuming, and highly variable between farms. The purpose of this paper is to report a simple laboratory procedure for estimating methane emission from stored manure. The test developed was termed a methane production rate (MPR) assay as it provides a short-term biogas production measurement. The MPR assay incubation time is short (3d), requires no sample preparation in terms of inoculation or dilution of manure, is incubated at room temperature, and the manure is kept stationary. These conditions allow for high throughput of samples and were chosen to replicate the conditions within deep-pit manure storages. The results from this assay predict an average methane emission factor of 12.2 ± 8.1 kg CH4 head-1 yr-1 per year, or about 5.5 ± 3.7 kg CH4 per finished animal, both of which compare well to literature values of 5.5 ± 1.1 kg CH4 per finished animal for deep-pit systems (Liu et al., 2013). The average methane flux across all sites and months was estimated to be 22 + 17 mg CH4 m-2-min-1, which is within literature values for deep-pit systems ranging from 0.24-63 mg CH4 m-2-min-1 (Park et al., 2006) and similar to the 15 mg CH4 m-2-min-1 estimated by (Zahn et al., 2001).