Land application of manure is a common source of neighbor complaints. University of Nebraska’s Rick Koelsch shared tips for minimizing manure odors in an Extension Dairy Bulletin.

Koelsch said that incorporation of manure is the best practice for controlling odors after application, as soil is an excellent filter to remove the smell released by manure. However, for various reasons, manure incorporation is not always feasible. If not incorporated, he said the 36-hour period after land application is the most critical, as this is when odors will be most noticeable.

When determining which fields to apply manure to, Koelsch said wind direction is the most important piece of information one can gather. Odor plumes will travel in the same direction as the wind. The edges of the field that are perpendicular to the wind direction will likely be most impacted by any odors. Watching the directional wind forecast for a 36-hour period after application allows farmers and applicators to select fields, when possible, that will least affect neighbors.

Night time hours, with cooling temperatures and light winds, are when people are more likely to be exposed to the smell of applied manure. That’s because the odor plume is not diluted and atomspheric conditions hold it close to the ground. During the day, Koelsch said odor plumes generally rise and are diluted with fresh air. Additionally, sunshine, wind, and warm air help to disperse odors.

Koelsch emphasized that weather forecasts providing wind direction and speed, sky conditions, and temperature are very valuable when determining when and where to apply manure. If a person is not able to wait for more desirable weather conditions, Koelsch said to focus on the nighttime wind direction and use this information to select an application site with the fewest downwind residences to minimize neighborhood exposure.