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A report from the AgTech Centre

Stockpiling manure not the same as composting

Producers who stockpile manure thinking they're producing compost, should think again, says an AgTech Centre researcher. Stockpiling and composting are two entirely different processes with entirely different results.

"Some producers believe as long as manure sits for a while, the pile eventually becomes compost," says Virginia Nelson, an engineer-in-training and composting researcher at the Alberta Agriculture Food and Rural Development (AAFRD) AgTech Centre. "Manure piled over a period of time simply becomes older, usually drier manure that retains some of the same features as raw manure."

Nelson's comments on the two approaches can be found in the latest issue of the AgTech Centre Innovator, which outlines the differences between stockpiling and composting manure and provides producers with background on the options available.

Nelson says the AgTech Centre has a number of projects related to composting and the world of composting is evolving rapidly with new options for managing manure.

Composting manure results in a product that is highly organic, free of weed seeds and harmful pathogens, such as E.coli and salmonella bacteria, and less harmful to the environment.

"Heat during the composting process destroys seeds and most of the harmful bacteria," says Nelson. "Manure volume is reduced by 60 percent, leaving less product to be handled or spread on fields. The compost also holds water well, which improves the soil's overall moisture content."

Stockpiled manure decomposes slowly with little oxygen, which is a key element in the composting process. Although stockpiled manure adds organic matter and nutrients to the soil, it also has a persistently strong odour when spread, weed seeds that can survive for a considerable amount of time and an environment where pathogens can thrive.

Producers need to assess their manure handling capabilities before determining which option best suits their operation. Feedlots with an adequate land base readily available for raw manure disposal might find composting just adds costs, says Nelson. However, smaller operations or those without sufficient land base may find that composting is a viable option. Cow/calf operators may not have the volume of manure necessary to produce the compost, but land-based operations, such as dairy, hog or poultry, which produce large manure volumes, may see composting as an excellent solution.

"Some hog producers with dry manure production systems compost manure and sell the composted product," says Nelson. "In some cases producers have delivered compost to a central location in a community where home gardeners can help themselves."

Producers looking at adopting a composting system should consider the costs and time involved, says Nelson. Drum-style turners are typically used to turn the windrow and break up large clumps of manure. These turners come in a variety of sizes and the price depends on the size and the type of equipment. Small three-point hitch models start at $15,000, while large self-propelled units cost around $250,000.

AgTech Centre research shows it costs approximately $8.46 per tonne to produce compost from feedlot manure. Nelson says that cost includes the use of a 120 horsepower tractor equipped with a tow-behind windrow turner used for about 400 hours per year.

"The bottom line is the value of composting depends on each individual operation," she says. "Producers need to ask themselves if their operation is suited for a composting system."

While manure is one product that can be easily composted, other agricultural "wastes," such as livestock mortalities, are being studied.

"We're finding composting can also be an economical and effective alternative to shipping dead animals for rendering, burial or incineration," says Nelson.

For more information and reports on composting options, producers are encouraged to contact AgTech Centre at (403) 329-1212 or visit their Web site, http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/eng3096.

AgTech Centre is part of Alberta Agriculture, Food and Rural Development's Technical Services Division and has a mandate to support all aspects of agricultural sustainability.

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