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. 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.