Mary Sowerby

UF/IFAS Dairy Extension



To be good stewards of the land, rivers and springs of this region, dairy producers must be mindful of not only the chemical fertilizer they apply to their soil, but also the natural fertilizer that falls behind cows in the form of manure.

One dairy producer, David Sumrall, owner of DPS-Branford Dairy, located in Gilchrist County just south of the Santa Fe River, has been perfecting a relatively new method of manure solids disposal by creating “cowpeat.” The term “cowpeat” was originally coined by those involved with the first drum composter used in Florida at Gore Dairy, Zephyrhills: entrepreneur Andy Tangeman from Agrigy, Inc., Palm Harbor; now retired UF Ag Engineering Professor Roger Nordstedt; former Department of Environmental Protection Ag Liaison Jemy Henson; and UF Dairy Extension Agent Mary Sowerby.

In much of the plant nursery world, peat is an essential component of potting soils. In days when the U.S. dollar was stronger against foreign currencies and freight was much cheaper, large quantities of Canadian peat were shipped to Florida to meet horticultural needs. Alas, the price for Canadian peat in Florida has skyrocketed. Native Florida peat has been used as a substitute, but Florida sources are fewer and fewer and problems of weed seed contamination exist.

Back at DPS-Branford, about 2,000 cows are housed in six loafing barns with sand-bedded free stalls for resting. Barn alleys are periodically flushed clean with recycled water. Sand is separated out of the manure-laden water for later reuse and the remaining slurry is stored in a retaining pond before being pumped to a solids separator.

The solids separator is a screened device which must get the separated solids below 60 percent moisture for the drum digester to work correctly. However, achieving a low moisture percentage has proven to be challenging at DPS and other dairies experimenting with drum composting. Through the use of a very fine screen and an extra “sacrificial” coat of paint to decrease equipment wear and tear by sand, the screening process has been perfected and the pile of resulting separated solids is the right moisture to be composted in the drum.

Next the separated solids are augured to one of the two side-by-side drum composters. These are horizontal cylinders 50-feet long and 10-feet in diameter with one foot diameter air holes centrally located at each end. The separated solids go into a drum composter one day and come out three days later.

The slow rotation of the drum keeps the enclosed separated solids moving and aerated. Microorganisms ferment (decompose with the release of gases) the contents and raise the temperature rapidly to between 150 and 170 degrees F. The heat kills weed seeds, nematodes and most bacteria resulting in a marvelous product for plant nurseries. Cowpeat looks and smells like natural peat, but grows plants better due to additional nutrients.

Cowpeat is a win-win product. It helps DPS-Branford and other dairies be environmentally friendly and the plant nursery industry solve its peat problem. If only all stories could end so well.

Extension programs are open to all people regardless of race, color, sex, religion, disability or national origin. In accordance with the Americans with Disabilities Act, any person needing a special accommodation to participate in any activity should contact the Suwannee County Cooperative Extension Service at 1302 Eleventh Street, SW, Live Oak, Florida 32060 or telephone 386-362-2771 at least five working days prior to the event. Hearing impaired can access the foregoing telephone by contacting the Florida Relay Service at 1-800-955-8770 or 800-955-8772 (TDD).