University of Illinois Extension researchers have tested the use of sawdust to compost liquid hog manure. They report low odor emissions and high quality compost, which was applied to add organic matter to sandy Illinois soil in Mason County, IL.

To begin the experiment, 50 gal. of agitated liquid finishing barn manure were mixed with each cubic yard of sawdust. The resulting compost contained about 50% moisture.

Duane Friend, natural resources extension educator in Springfield, IL, explained that about 2,000 gal. of manure and 40 cu. yd. of sawdust were used to make four piles that were 4 ft. high by 15 ft. wide by 20 ft. long. The piles were made using a tractor with a front-end loader.

After 13 months, samples were taken and tested for E. coli and salmonella. Three of the four piles had less than 0.3/gram of E.coli and no salmonella.

The fourth pile had 2.1/gram E. coli and tested positive for salmonella. Friend theorized that the fourth pile didn't have the appropriate amount of moisture and therefore did not compost as efficiently as the other piles.

The compost was spread with a box spreader at two rates — 30 tons/acre and 15 tons/acre — on two plots of sandy soil planted with pumpkins and squash. A control plot received no compost.

Testing revealed that the composted manure increased the organic matter of the soils by 1-2% in the first year of application. The compost had significantly increased the organic matter in the top 5 in. of soil.

“We took samples last summer and found that the organic matter was higher in the plots treated with manure than in the control plot,” Friend says.

He suggests that producers could use existing equipment — tractor with front end loader and a box spreader — to start composting.

A PTO-driven compost turner and a tractor with a super-low gear (1/10 mph) are needed for more intensive composting.

Friend estimated that the compost piles required 20 hours of labor during the 13-month process, including spreading the compost.

The study was funded by a grant from the Illinois Department of Agriculture's Sustainable Agriculture Program.

Researcher: Duane Friend, University of Illinois. Contact him at (217) 782-6515 or email friendd@mail.aces.uiuc.edu.