Manure can have value if managed correctly. This value can be spread out over multiple years. The first year, 30 to 40 percent of the nitrogen (N) is available along with almost all of the phosphorus (P) and potassium (K). The second year, 10 percent of the N from the first year's is available and P and K not used in year one will still be useable. Year three has 5 percent N and any remaining P and K available for use.
The first year usually sees the highest benefit from the manure. Each following year will receive less value from the initial application.
Other factors to consider in valuing manure include organic matter value, compaction, timeliness and application costs.
To maximize manure benefits, test manure before application, calibrate application equipment, incorporate manure to retain nutrients, test soils and apply manure only where needed. PD
Dan Huyser is an ag engineering program specialist for Iowa State University Extension.
—Excerpts from 2013 Iowa Dairy Days proceedings
