A new web site that provides information on research, preliminary results and guidelines for composting cattle has been set up by Iowa State University.

The web site, www.abe.iastate.edu/cattlecomposting/, is organized to meet the needs of three different groups. For producers and others who want to skip the science and just “learn how to do it”, there is a link to “Draft Guidelines for Emergency Cattle Mortality Composting.” Those with a casual interest in the project should find what they want on the executive summary page. For others who want more in-depth information, page links listed under “Project in Detail” will describe the project in detail.

ISU began composting beef cattle in the fall of 2002 at the request of the Iowa Department of Natural Resources. The agency wanted to have on-farm emergency disposal measures to deal with the aftermath of a disease outbreak or agro-terrorism, said Tom Glanville, project coordinator and associate professor for agriculture and biosystems engineering. More than 40 tons of carcasses were composted during the first 16 months of the project.

It generally takes eight to 12 months—“surprisingly rapid”—for soft tissues and organs of a 1,000-pound carcass to decay under the three cover materials that ISU tested. Since temperatures noticeably affect decomposition, some trials during warm weather took less than six months.

Glanville said shorter times are feasible when compost piles are turned frequently. ISU did not turn the piles because the project is designed to simulate likely disposal procedures during a livestock disease emergency. In that case, turning could increase the risk of disease transmission.

“Decay is surprisingly good without turning at all. That’s been a big surprise to many people, including us,” he said.

The three cover materials tested—silage, ground cornstalks and a hay/manure mix—are easily available on Iowa farms. They appear to bring about carcass decay in about the same amount of time. Corn silage, however, has the best potential for killing pathogens because it typically produces the highest core temperatures in the shortest amount of time, Glanville said.

Yard waste clippings were also used as cover in several trials. But decomposition within the fine-textured yard waste was highly variable and unacceptably slow. Although soft tissue decay appeared to be complete near the outer edges of the pile, decay was incomplete and highly odorous at the core and bottom.

Glanville said that results might have been very different with another type of yard waste. Clippings that were more porous would have allowed a higher amount of oxygen into the pile.

There have been low amounts of odor near the windrows. In many cases, odor from the windrows cannot be distinguished from the odor of cover material. He attributes much of the odor reduction to the two feet of cover material that is placed below carcasses.

Composting of cattle was first done in states with low annual rainfall. Upon starting the project, Glanville was uncertain whether the practice would work well in Iowa since the state receives considerable rainfall in the spring and early summer. Although he strongly advises pork producers to compost in bins under a roof, that is impractical for larger animals.

But after conducting trials for more than one and one-half years, Glanville said there are good results in terms of decomposition and lack of odor. ISU will continue its cattle composting research through June of 2005.

Funding comes through a continuing grant from the Iowa Department of Natural Resources, with supplemental funds from the U.S. Department of Agriculture. ©