This document is applicable to fertilizing products, which are classified as PFC 1(A) or PFC 1(B) of Regulation (EU) 2019/1009 [5]. However, the present method was not validated for blends. This document specifies a method for the determination of the total nitrogen content and the content of ammoniacal, nitric, ureic and organic nitrogen in organic and organo-mineral fertilizers. This method is based on EN 15604:2009 and adapted to be applicable to organic and organo-mineral fertilizers.