Synthetic covers usually are made of plastic. Other covers are made of wood or concrete or biodegradable materials such as hay or straw. Manure storage covers work by interrupting the flow of gases up from the liquid surface into the atmosphere. Iowa law recognizes the effectiveness of covers by reducing the separation distance between covered pits and neighbors. Odor evaluations of covered and uncovered concrete pit by field day attendees.
Higher numbers indicate more odorous air.
In the odor demonstration project, synthetic covers significantly reduced odors when 100 percent of the storage surface was covered. To be effective, covers must be firmly attached to prevent the wind from catching and whipping them, and they must cover as much of the storage structure as possible. When less than 100 percent of the surface is covered, the odor reduction is much less dramatic. Figure 1 shows how field day attendees evaluated a covered and uncovered storage at one of the demonstration sites. Floating plastic covers are the most popular type of synthetic cover.