New design in building handles hog manure as a solid commodity
A new design in hog housing dries manure with fans to produce a low-odor, high-value solid that can be used as an alternative to chemical fertilizers.
The design, called the Hi-Rise Hog House, is modeled after poultry barns. Hogs are raised on an elevated second level. Manure collects on the first level in an above-ground, bedded pit, where it is dried with fans.
Unlike chickens, hogs produce urine. To absorb the extra moisture, 11/2 ft. of bedding are added to the pit, and fans force air up through small holes in the floor and out through the sidewall fans that are used to ventilate the hogs.
Why dry? In conventional hog barns, manure is stored as a liquid below ground. But when liquid manure starts to break down, it releases odorous gases.
"Only in the last 30 years has it been decided that manure must be handled as a liquid for ease of use," says Thomas Menke, president of EnviroLogic Corporation, which holds the patent to the design. "But 400 years prior, hogs were raised out in the open or in pens on bedding, and manure was handled as a solid."
Solid manure has less odor than liquid because it is stable and lighter in weight, which makes it easier to transport. It also is less likely to leach into groundwater or run off into stream once it is applied to fields.
Performance tested. A group of hogs was raised in a 1,000-head finishing building based on this concept from mid-July through October 1998. Performance was compared with 11 other herds of the same genetics that were managed identically in conventional hog barns.
The test group outperformed the other groups in all categories, including feed efficiency, daily gain, days to finish, mortality, culls and percentage back fat. Menke attributes the advantage to better air quality. "We feel confident that there is no better way to ventilate because no air from the pit can get up to the animal quarters," Menke says.
Dr. Harold Keener, agricultural engineer with Ohio State, has been monitoring air flow and air quality in the building. Ammonia levels in the second story averaged 5 to 8 ppm - well within the desirable range for growing hogs, Keener says. Levels in the pit averaged 15 to 20 ppm. Ammonia detected outside of the pit fans quickly dissipated. No hydrogen sulfide gas, which is associated with liquid manure, was detected.
The building is designed to handle three groups of hogs per year. Most of the same bedding can be reused year-round, but dry areas should be mixed with wetter areas to aid composting between groups.
High-value end product. A 1,000-head finishing building should produce 500 tons of semi-composted product per year. Each ton as-is has a nutrient value of $12 and contains 24 lbs. of nitrogen, 63/4 lbs. of ammonia nitrogen, 30 lbs. of phosphate and 25 lbs. of potash.
Dr. Harry Hoitink, plant pathologist with Ohio State who is researching the composting aspects of the project, says hog manure is a valuable commodity. "The product will have slightly lower nutritional content because part of the nitrogen is lost when you compost," Hoitink says. "But it will be a stable product that can be stored without problems and marketed when the market is right and when weather and cropping conditions are perfect."
The design, which soon will be launched commercially, can work in any size operation and any stage of growth, Menke says. Building costs are quoted as 10 to 15% higher than normal deep pit buildings. Operating costs will also be higher due to bedding and power ventilation.
Contact EnviroLogic Corp., Dept. FIN, 6070 Routzong Rd., Greenville, OH 45331, 937/447-2455.