Spring 1998
Try a biocover to reduce odor
by Tracy Peterson, extension communications and Jeff Lorimor, extension agricultural and biosystems engineer
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.
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.
