Use of a cation source comprising a cation C m+ , wherein C m+ is Ca 2+ , Mg 2+ , Li + , Fe 2+ , Fe 3+ , Al 3+ , Ag + , Cu 2+ , Zn 2+ , Hg 2+ , Pb 2+ , Ba 2+ , or a quaternary ammonium group comprising at least three groups selected from C 1 -C 2 -alkyl and C 1 -C 2 -hydroxyalkyl; in a composition A comprising (i) a (thio)phosphoric acid triamide according to general formula (I) wherein X 1 is O or S; R 1 is C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 6 -C 20 -aryl, C 6 -C 20 -aryl-C 1 -C 4 -alkyl or C 1 -C 6 -(di)alkylaminocarbonyl; R 2 is H, C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 6 -C 20 -aryl, C 6 -C 20 -aryl-C 1 -C 4 -alkyl or C 1 -C 6 -(di)alkylaminocarbonyl; or R 1 and R 2 together with the nitrogen atom linking them define a 5- or 6-membered saturated or unsaturated heterocyclic radical, which optionally comprises 1 or 2 further heteroatoms selected from the group consisting of N, O and S; and R 3 , R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of H and C 1 -C 4 -alkyl; and (ii) a fertilizer mixture comprising a urea-containing fertilizer and an additional P-containing fertilizer which is preferably a NPK fertilizer, a NP fertilizer, a PK fertilizer or a P fertilizer; to prevent decomposition of the (thio)phosphoric acid triamide wherein the cation source is a salt, which further comprises an anion A n- , wherein A n- is F - , Cl - , Br, I - , SO 4 2- , NO 3 - or CH 3 CO 2 - . (i) a (thio)phosphoric acid triamide according to general formula (I) wherein X 1 is O or S; R 1 is C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 6 -C 20 -aryl, C 6 -C 20 -aryl-C 1 -C 4 -alkyl or C 1 -C 6 -(di)alkylaminocarbonyl; R 2 is H, C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 6 -C 20 -aryl, C 6 -C 20 -aryl-C 1 -C 4 -alkyl or C 1 -C 6 -(di)alkylaminocarbonyl; or R 1 and R 2 together with the nitrogen atom linking them define a 5- or 6-membered saturated or unsaturated heterocyclic radical, which optionally comprises 1 or 2 further heteroatoms selected from the group consisting of N, O and S; and R 3 , R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of H and C 1 -C 4 -alkyl; and X 1 is O or S; R 1 is C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 6 -C 20 -aryl, C 6 -C 20 -aryl-C 1 -C 4 -alkyl or C 1 -C 6 -(di)alkylaminocarbonyl; R 2 is H, C 1 -C 20 -alkyl, C 3 -C 20 -cycloalkyl, C 6 -C 20 -aryl, C 6 -C 20 -aryl-C 1 -C 4 -alkyl or C 1 -C 6 -(di)alkylaminocarbonyl; or R 1 and R 2 together with the nitrogen atom linking them define a 5- or 6-membered saturated or unsaturated heterocyclic radical, which optionally comprises 1 or 2 further heteroatoms selected from the group consisting of N, O and S; and R 3 , R 4 , R 5 , and R 6 are independently of each other selected from the group consisting of H and C 1 -C 4 -alkyl; (ii) a fertilizer mixture comprising a urea-containing fertilizer and an additional P-containing fertilizer which is preferably a NPK fertilizer, a NP fertilizer, a PK fertilizer or a P fertilizer; to prevent decomposition of the (thio)phosphoric acid triamide wherein the cation source is a salt, which further comprises an anion A n- , wherein A n- is F - , Cl - , Br, I - , SO 4 2- , NO 3 - or CH 3 CO 2 - . to prevent decomposition of the (thio)phosphoric acid triamide wherein the cation source is a salt, which further comprises an anion A n- , wherein A n- is F - , Cl - , Br, I - , SO 4 2- , NO 3 - or CH 3 CO 2 - . <EOS>