Mixing hog manure and sawdust into compost could be management option

SPRINGFIELD, Ill. – Call it the sawdust solution. A field study conducted by University of Illinois Extension showed that mixing sawdust with hog slurry controlled odor and added organic matter to fields on a farm over a two-year period.

“There was almost no odor from the slurry, even as we were mixing it with sawdust,” said Duane Friend, an Extension educator based in Springfield.

Composted in piles. During the study, 50 gallons of slurry were mixed with each cubic yard of sawdust, creating a compost that had about 50 percent moisture.

A bucket tractor was then used to make four piles, which were roughly 4 feet high, 15 feet wide, and 20 feet long on the hog producer’s land.

After five months, samples taken from each pile showed the composting process had been effective, Friend said. Soluble salts, nitrates and pH were all within acceptable ranges. Also, the heat killed most of the Salmonella and E. coli bacteria.

In June of 2000, the compost was applied to sandy soils with low organic matter, 13 months after composting began. Researchers applied compost at a high rate of 30 tons per acre and low rate of 15 tons per acre on a field planted with pumpkins and squash. A control plot received no compost.

“We took samples last summer and found that the organic matter was higher in the plots treated with manure than the control plot,” Friend said. In fact, organic matter was 1 percent to 2 percent higher. The compost had significantly increased the amount of organic matter in the top 5 inches of the soil.

Although yield results were unavailable, the crop producer said that weed pressure appeared to be less in the compost plots, Friend said.

Implications. He noted that this field trial did more than show that composting manure is an option for hog producers and a good way to add organic matter to sandy soils. The sawdust solution may even help sawmills.

Friend also wanted to show that composting could be done with a producer’s existing equipment.

“It takes some time and effort, but it could work well for producers who cannot put all the manure directly on fields,” Friend said.