Emergency Livestock Disposal Home

Project Executive Summary

Project in Detail

• Background
• Objectives
• Composting System Tested
• Research Methods
• Preliminary Results
• Construction & Maintenance
• Temperature
• Oxygen
• Decomposition
• Cover Materials
• Air quality
• Water quality
• Biosecurity
• Project Sponsors & Contacts

Draft Guidelines for Emergency Cattle Mortality Composting

PRELIMINARY RESULTS


Windrow Construction & Maintenance

During the first 16 months of this project more that 40 tons of cattle carcasses have been composted, and much practical experienced has been gained regarding construction and maintenance of windrow composting operations.

The following practical observations are offered for the benefit of researchers and educators embarking on similar cattle composting research/demonstration projects, and for cattle producers interested in using composting for on-farm mortality disposal. 

Equipment

A tractor equipped with a detachable bucket and pallet fork has proven invaluable.  A large capacity bucket is essential for moving and placing large volumes of base and cover materials beneath and over the cattle carcasses, and the detachable pallet fork has proven invaluable in the difficult task of lifting, transporting, and positioning large cattle carcasses on top of the base materials.

Windrow Size and Material Requirements

Base Width Important

An anticipated base width of 12 feet that was based on published dimensions for full sized cattle, proved to be too narrow.  Coupled with the inherent difficulty in positioning carcasses precisely on a narrow base, inadequate base width resulted in frequent carcass exposures during the early trials, and required constant addition of cover material.  Base widths of all test units have been increased to 16-18 ft. to avoid these practical problems.

Cover Material Requirements

Fairly large volumes of base and cover material are required, beneath the carcasses to absorb excess moisture, and over them to retain heat, retain odors, shed precipitation, and discourage invasion by insects and rodents. 

Using the pile dimensions and loading pattern described in Research Methods - Construction (17-foot average base width, 20-foot length, and peak height of 7 feet) test units constructed for this project require about 15 cubic yards of base/cover material per 1,000 lbs of carcasses composted.  In on-farm practice, 12-13 cubic yards per 1,000 lbs may be adequate since about 5 feet of extra pile length was used in the research test units to accommodate placement of temperature probes and virus access ports that would not be used in normal practice.

Initial densities for cover materials placed with a tractor loader were determined by dumping several large bucket loads of each type of cover material into a wagon equipped with load cells and recording the resulting weight and volume of the material.
 

Using this procedure, the following initial in-place densities were calculated. 

 Combining these initial in-place density estimates with an average cover/base material volume of 12 cubic yards per 1,000 lbs of carcasses yields the following mass requirements for each type of cover material.

Pile Height, Settling, & Maintenance

A 24-inch base layer,  single layer of carcasses, and sufficient material to cover the carcasses (minimum cover 18-inches) and shed precipitation, typically results in centerline pile heights of approximately 7 feet (approximately 1/2 of the base width). 

Test units, particularly those constructed with silage, exhibited very rapid settling during warm weather.  The photo below shows a silage test unit as it appeared the day that it was constructed (April 22, 2003). 

Only 45 days later (June 6, 2003) the same test unit had settled to half of the original height (note that pitch fork at toe of silage test unit is only 42-inches tall). 

Rapid settling leads to formation of cracks and depressions which require occasional additions of cover material to repair carcass exposures and avoid attracting flies. 

Despite seasonal exposure to high winds, snow, and thunderstorms, wind erosion and water erosion have not been significant for test units constructed with any of the three cover materials.  Wind damage has been held to a minimum by the relatively low initial profile (approx. 7 ft) of the windrows, further substantiating the benefits of using no more than a single layer of carcasses disposing of full-sized cattle.  Lack of water erosion is attributed largely to the porosity of the cover material which absorbs rainfall rather than permitting it to run off.

In Brief

1.  Limiting the test units to a single layer of full-sized cattle carcasses (no stacking) has held wind and water damage to a minimum and also has avoided excessive pile collapse and a resulting need for frequent pile maintenance.  

2.  The segments of the research test units that contain carcasses require about 12 cubic yards of cover/base material per 1,000 lbs of cattle carcasses. (Note: for research purposes, buffer  segments on each end are used to separate the test units ) This is equivalent to 1 ton of ground hay or straw, 1.4 tons of ground cornstalks, or 3.2 tons of corn silage.

3.  Settling of as much as 50% of initial pile height is typically observed during the first 90 days of composting.  Stockpiled cover material is used to repair settling cracks or holes that lead to carcass exposure.