Nutrient Credits from Manure

Average manure nutrient content values provide estimates that can be used for nutrient management planning.  However, manure nutrient concentrations can vary significantly among different farms due to animal species, size and number of housed animals, feed ration, and manure handling and application method.  To meet both economic and environmental objectives, it is important to know the content and availibility of nutrients in the manure so that the application rate can be determined to match crop need.  Information about sampling manure can be found at: http://ag.umass.edu/crops-dairy-livestock-equine

Typical values for nutrient content of manure

Availibility of Nutrient in Manure

Nitrogen in manure consists of two fractions.  Approximately half of N is in the form of ammonium (someitmes called inorganic) which is available to plants the year of application.  The remainder of N is the organic form and releases N into soil over a longer period of time.  The ammonium fraction however, is very susceptible to large losses mainly through volatilization.  It has been shown that ammonium fraction of manure can be entirely lost to the environment within the first 48 hours when surface applied.  Therefore, incorporating manure into soil immediately after application is highly recommended.  The availibility of N in the organic fraction is about 10% of the total N, with 5% and 2% availibility in the second and third years after application.  The phosphorus in manure is available only slowly to a crop; however, manure P is not fixed readily into unavailable forms in the soil like highly soluble P fertilizers are.  The net result is that the P in manure is very similar to the P in fertilizers in meeting the requirements of crops.  Since manure P is not available soon after application in certain conditions such as low soil temperature, application of starter fertilizer may benefit crop growth.   

Resources

Agronomy Fact Sheets.  Cornell University nutrient management spear program.  nmsp.cals.cornell.edu/guidelines/factsheets.html

Nutrient Recommendation for Field Crops in Vermont.  University of Vermont Extension.  pss.uvm.edu/vtcrops/articles/VT_Nutrient_rec_field_crops_1390.pdf

The Agronomic Guide 2013-2014.  College of Agricultural Sceinces, Penn State.  extension.psu.edu/agronomy_guide

This factsheet was prepared by Masoud Hashemi, Sarah Weis, and Madeline Magin