Whether to enrich fields with manure is a dilemma for some producers who use no-till practices in their farm operations.
"Best management practices for manure applications call for incorporating the material into the soil, and there are applicators that can inject the manure into the soil without creating too much disturbance," says Kansas State University agronomist Dave Whitney. "But conventional surface applications of manure can pose a problem for no-till producers, since it is not possible to incorporate it after application."
Although surface application of manure, without incorporation, does raise some concerns, that does not mean manure cannot be used on no-till fields, notes Whitney, who is a soil fertility specialist with K-State Research and Extension. Actually, most of the sound application practices used for manure application on conventional-till fields still apply. The correct application rate and uniform spreading are still necessary to derive maximum benefits.
The major concerns from application of manure to no-till fields are the potential for: (1) manure to move off-site in surface water runoff, (2) odor problems, and (3) ammonium-nitrogen volatilization loss, says K-State's Dan Devlin, who is an environmental quality specialist. All of these potential problems are minimized by incorporation.
To minimize runoff potential, manure should not be applied during months in which precipitation events are most likely, or when ground is snow-covered or frozen. Application on steeply sloping land and near surface water sources without vegetative filter strips also should be avoided, Devlin says.
Little can be done to minimize ammonium-nitrogen volatilization from surface applications of manure, Whitney says. Ammonium-nitrogen volatilization is slower in cooler temperatures, but without incorporation or precipitation to move ammonium into the soil within a couple days, ammonium-nitrogen loss will be substantial regardless of the air temperature. Most feedlot manure contains little ammonium-nitrogen, however, so losses from that source are of little concern.
"To manage objectionable odors from surface-applied manure, the manure should not be applied close to residences, or when prevailing winds are blowing toward residences," Devlin says. "There really are few other options."
If the manure is from a facility that is under regulations for land application of manure, the nutrient management regulations must be followed for rate and method of application.