Commercial Agriculture Program
Fall 2009
2009 Beef Tour demonstrates large animal composting
By Michelle Proctor, Senior Information Specialist
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| John Hoehne, with help from Rex Ricketts, gives pointers for on-farm anlimal composting |
University of Missouri Extension Commercial Agriculture Program’s 2009 Beef Tour was held in Dent, Phelps and Crawford Counties on August 29. The tour offered an opportunity for producers to visit several types of cattle operations and pick up advice on how to best manage their own.
The 13th annual Tour attracted nearly 300 people. Tour stops included a high stock density operation, a managed intensive grazing system, a backgrounding operation, a silvopasture facility, and a Hereford seedstock operation.
A cow composting demonstration by University of Missouri Extension Commercial Agriculture Program, agricultural engineer, emeritus, John Hoehne, illustrated how inexpensive, and most relevant—odorless, composting dead animals can be.
On-farm cow composting has become an important issue since rendering plants no long pick up dead livestock. Hoehne showed producers how to build a shallow pit, layer it with at least one foot of sawdust, enclose it securely on three sides—Hoehne used concrete highway bunkers—to contain runoff from wind or rain, and cover the animal with sufficient sawdust to leave no parts of the carcass exposed.
Hoehne recommended a sawdust "envelop" of 18 to 24 inches covering the carcass. "That will give you a start towards to the target C:N ratio of 25:1. This will help ensure that odors do not escape," said Hoehne.
"You want heat-loving (thermophylic), oxygenusing (aerobic) bacteria to do the decomposition work for you," said Hoehne. "Some moisture, but not too much or all the pore spaces will fill with water and the bacteria won’t do their job. They will drown and you will be stuck with odors."
Hoehne told viewers to plan on a minimum of 200 cubic feet of sawdust per 1,000 pounds of carcass. He recommended puncturing the abdominal cavity after laying the animal on the sawdust base, but prior to covering the carcass with the remaining sawdust.
Hoehne recommended using a thermometer to monitor the internal temperature of the composting site (110º to 150º F). He cautioned producers to monitor the site to ensure that the proper balance of air and moisture are present.
Hoehne also recommended not turning the animal for one year, and to be prepared to add additional sawdust as the carcass settles.
"When the decomposition is complete", Hoehne said, "you will be left with some large bones and a soil-like product."