Question: If only 85% of nitrogen is available the first year in manure, how much can I count on for the second year?
Answer: The amount of nitrogen (N) that is available the first year will be highly dependent on the type of manure and the application methods you use. For example, between 50% and 60% of the N in poultry manure is typically available the first year (before any loss), and 0% to 10% the second year. Animal manure that has considerable organic material can have some residual N availability in the second or third year after application; however, manure sources that have low organic N will not have second-year crop available N (Iowa State University, PMR 1003, September 2008). In general, you can expect the N availability from manure to be low in the second year (0-10%); but again, that will depend on several factors. The best thing to do is have your manure analyzed at a laboratory for N availability. Most labs that do soil testing also do manure testing. Keep in mind that the percent available does not take into consideration N loss from volatilization, leaching, or denitrification. Application methods are highly influential in volatilization loss.
