There are three points in time when manure is typically applied to alfalfa.  These include:  prior to alfalfa establishment, following a summer harvest of an established alfalfa stand, and during the fall of the terminal year.  It’s the summer application that deserves some attention at this time. 

        Topdress applications of manure are sometimes made on recently harvested alfalfa fields because of the necessity to spread manure during the summer months. Why does this happen?  Often it is because not enough manure storage capacity was constructed initially or cow numbers have outgrown the existing storage structure.  Applying manure to established alfalfa does offer the ability to spread manure in the summer and provides a means to utilize “on-farm” nutrient sources rather than purchased commercial fertilizer.  Both research trials and farmer experiences have been mixed using this strategy of manure application to alfalfa.  In some cases, yields have been increased and no detrimental impacts to alfalfa plants were noted.  In other situations, both stand and yield reductions have occurred.  The latter have been attributed to: 

·      Manure salts and free ammonia causing damage to new alfalfa regrowth.

·      Plant crown or shoot damage from wheel tracks.

·      Soil compaction (especially if soils are wet) from manure application equipment.

·      Plant smothering (mostly a problem with solid manure forms) 

        The other potential disadvantage to applying manure on established alfalfa is odor.  With no option to
work the manure into the soil, public relations with nearby neighbors can become a bit dicey.  If the need exists to apply manure to established alfalfa, follow these guidelines: 

·      Make applications immediately after harvest to reduce the risk of plant damage from both salt burn and wheel track damage.  UW research has confirmed that wheel track damage to alfalfa is significantly greater after five days of regrowth compared to three.

·      Skip applications if soils are wet.  This will reduce soil compaction risks.

·      Target older stands where there is less to lose if plant damage does occur.  Additionally, older stands often have more grasses or weeds that contribute to yield and are less prone to damage from manure applications.

·      Don’t apply more than 3000-5000 gallons per acre of liquid manure or about 10 tons of solid dairy manure.  Also keep in mind that burn potential is a function of manure ammonium nitrogen and salt content.  These vary with manure type and source.

·      Apply manure uniformly across field.