Dairy manure is a valuable source of N for crop production in Wisconsin. Accurate estimates of dairy manure N availability in the first- and subsequent residual-years after application are needed to maximize crop N uptake and reduce N losses to the environment. This study examined dairy manure N availability and mineralization of dairy manure components using various methods. A 6-year field trial estimated the first-, second-, and third-year dairy manure N availability using (1) the apparent recovery method (difference method) (2) the fertilizer N equivalence method and (3) recovery of 15N labeled manure. Manure N release was also studied in the field trial using a mesh litterbag. A laboratory incubation study was conducted in which 15N-labeled or unlabeled feces, urine, and oat straw bedding were incubated in soil for 168 days.