June 18, 2007

Contact: Quirine M. Ketterings, Cornell University, 607-255-3061; local Cornell Cooperative Extension offices

Too Much Manure? Spreading on Alfalfa Do�s and Don�ts Now Online

Too much manure? A new link on the he Northern New York Agricultural Development Program website at www.nnyagdev.org  provides information on applying manure to an established alfalfa crop online. The practice of properly fertilizing alfalfa is becoming increasingly useful to dairy farmers as government restrictions require judicious management of manure as an on-farm nutrient source.

�Nutrient management plans in many dairy regions of the U.S., including New York State, require that manure application to corn and forage grasses be limited to only the amount of nitrogen needed by the crop. This restriction increases the likelihood that manure will need to be applied to alfalfa fields to take up excess manure,� says Dr. Quirine M. Ketterings, an associate professor of Crop and Soil Sciences at Cornell University.

Kettering adds that newly harvested alfalfa fields may at some times, for example, during the summer cropping season, be the only fields accessible for dairy spread operations.

Ketterings, Karl Czymmek, a Senior Extension association with Cornell�s PRO-DAIRY program, and an interdisciplinary team of Cornell colleagues including NYS Forage Specialist Dr. Jerry Cherney, Animal Science Professor Dr. Larry Chase, and Quality Milk Production Services Director and Population Medicine and Diagnostic Sciences Professor Ynte Schukken, conducted a review of scientific literature on the benefits and disadvantages of manure application to established alfalfa.

Some of the findings of that literature review include:
� Established mixed alfalfa-grass stands with more than 60 percent do respond to extra N because of the grass in the stand. These stands are better alternatives for manure application than newly established clear seedings of alfalfa.

� Fertilization of a mixed alfalfa-grass stand tends to favor the grass over the alfalfa resulting in greater N needs with age of the stand.

� Nitrogen addition suppresses but does not eliminate N fixation. Manure application rates should not exceed the equivalent of 75-85% of N removed in harvest to minimize annual manure N losses.

� Surface application of manure leads to N losses through volatilization. In addition, deep cracks in the soil, root channels, and earthworm burrows can promote preferential flow of manure to tile drains, so tile outflow should be watched.

� Alfalfa is sensitive to traffic damage. Such damage can be minimized by planting traffic tolerant varieties, using small tractors for cutting, raking and harvest, avoiding unnecessary trips across the field, using larger harvesting equipment, avoiding tractors with dual wheels, and driving on fields as soon after cutting as possible.

� Delaying manure application after harvest increases burn risk and salt injury as new leaves are most sensitive to ammonium and salts in the manure. To reduce the risk of burn, smothering and/or salt injury, liquid manure application rates should not exceed 4,000 gallons/acre per application.

� Soil test P levels should be monitored over time as manure application rates in excess of 4,000 gallons/acre per year will likely result in a P application that exceeds P crop removal.

� Manured fields should be checked for forage K content if the forage is being fed to non-lactating cows. It is recommended to only feed forage with less than 2.5% K (DM basis) to non-lactating cows.

� Application of manure from animals infected with pathogens, particularly Johne�s disease is a potential method of spreading these infections. In the case of Johne�s disease, young animals (<1 year) should not have access to contaminated pastures or to feed from such fields.

� Although from a water quality point of view, summer application of manure has great advantages, odor control measures should be implemented when manure is being applied to sods in the summer months.

A link to the Cornell fact sheet on the Application of Manure to Established Alfalfa is on the Northern New York Agricultural Development Program website at www.nnyagdev.org in the Project Fact Sheets section. # # #