Odor and Nutrient Management Newsletter

Spring 1998

Try a biocover to reduce odor

by Tracy Peterson, extension communications and Jeff Lorimor, extension agricultural and biosystems engineer

Cornstalks are chopped and floated on manure in a round concrete swine tank.Warmer temperatures are on the way and with them comes the return of odors from livestock operations. Spring, therefore, is the ideal time for applying biocovers to outside liquid manure storage units.

Biocovers consist of fibrous biological materials such as straw or chopped cornstalks blown on top of liquid storage units. They provide a physical aerobic barrier between the liquid manure surface and the air. The covers float on storage units until fall, when they are removed with the manure, chopped, and spread on land.

The practice, while simple, promises to dramatically reduce odor emissions from livestock operations, see Figure below.

Odor ratings for swine manure pits with and without biocovers. 0 = no odor, 1 = barely detectable odor, 2 = noticeable odor, 3 = strong odor.To be successful, biocovers must completely cover the structure throughout the entire season. Biocovers must be at least eight inches deep to accomplish this. Most producers blow the materials onto the pits or lagoons with blowers similar to the ones used by highway departments or with wagons with choppers used to bed free-stall dairy barns. Producers often borrow the blowers or hire someone to apply the materials.

Biocover costs include both the materials and the cost of applying them. Unlike synthetic covers, biocovers require annual recurring costs. Biocovers cost about 10 cents per square foot of pit surface each time the cover is applied. Based on a 10- to 12-foot deep pit for finishing hogs, the cost ranges from 25 cents to 40 cents per head marketed.

Thirteen cooperators are demonstrating biocovers as part of the Iowa Odor Control Demonstration Project. Those producers are using wheat and barley straw, old CRP hay, chopped cornstalks, hay with oil on it, and barley hulls via the feed ration. Most of the biocovers have worked well, resulting in significantly reduced odors from manure storage pits.

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Iowa Manure Matters: Odor and Nutrient Management is published by Iowa State University Extension, with funding support from the USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-8-22. To subscribe or change the address of a current subscription, write to Angela Rieck-Hinz, 2104 Agronomy Hall, Iowa State University, Ames, Iowa, 50011-1010 or call 515-294-9590, fax 515-294-9985 or email: amrieck@iastate.edu. Please indicate you are inquiring about the Odor and Nutrient Management Newsletter. The newsletter's coordinators are Angela Rieck-Hinz, extension program specialist, Department of Agronomy, Wendy Powers, environmental extension specialist, Department of Animal Science, and Robert Burns, Department of Agricultural and Biosystems Engineering; the editor is Jean McGuire, the subscription manager is Rachel Klein, the production designer is Beth Kroeschell, and the web page designer is Liisa Jarvinen.

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