Study: Manure storage covers reduce odors by an average of 45 percent

WASHINGTON – A two-year research study funded by the pork checkoff shows that use of a geotextile cover reduced odors from manure storage by an average of 45 percent.

For this research project, pork producers on the pork checkoff’s environment committee selected the geotextile cover BioCap, marketed for lagoons and manure storages by Baumgartner Environics Inc. of Olivia, Minn.

Geotextile is a non-woven permeable material made of chemical compounds, such as polypropylene. The geotextile cover provides a physical barrier to odorous compounds in manure, minimizing the emissions of these compounds to the atmosphere.

“Odor emissions were reduced by nearly half using the geotextile cover in this study,” said John Kellogg, committee chairman and Illinois pork producer. “The results may be different in other conditions. Whether or not the odor reduction is enough depends on each individual operation.”

The study. The field scale study was conducted on six farms. Three pairs of farms were similar in production capacity, nutrition and manure storage surface area so that one farm was a control and the other a test for the geotextile.

Pork producers who participated in this Checkoff-funded research project described their experiences with the covers:

* “Neighbors say the smell is better after I put the cover on.”

* “I think the cover is effective in controlling odor, but we had a hard time making the cover float after the first season.”

* “I would probably install a cover again if they could find a better way to access manure for agitation and pumping, and make the cover float after pumping.”

A lift system was developed for this project. Because of the weight of the cover and worker safety issues with the lift, other agitation solutions should be investigated.

Odor reduction due to the geotextile cover averaged 45 percent during the two-year period. The largest reductions of hydrogen sulfide were in the first year of the test. Hydrogen sulfide concentrations surrounding the basins were nearly always lower around the geotextile-covered basin. Ammonia reductions were minimal.

“The cost of a geotextile cover for manure storage can be several thousand dollars, with additional fees for disposal,” Kellogg said. “Over time, this method could be as cost-effective as other methods to control orders. These covers are expected to last three to five years.”

Project completed. When this research project was completed, one of the three covers was removed. The disposal cost to a landfill was approximately $1,800 for a cover that measured 165-by-160 feet. The cost for the cover ranges from 14 cents to 22 cents per square foot, based upon the area of the manure surface plus additional material to anchor the cover.

This pork production operation, which markets approximately 5,200 market hogs per year and stores manure in an earthen basin with a geotextile cover, could expect a cost of 49 cents per hog marketed over a three-year useful life of the cover or 29 cents over a five-year useful life, which includes disposal.