Use of at least one surfactant as a compatibility agent for a herbicidal formulation, said formulation comprising at least one amine salt of a phenoxyacid herbicide, to prevent the formation of insoluble salts of said phenoxyacid herbicide in the presence of cations that are not of amine, where said compatibility agent is selected from the group consisting of i. an alkoxylated quaternary surfactant of the formula: ** (See formula) ** where R 1 is a saturated or unsaturated straight or branched chain alkyl group having from 8 to 22 carbon atoms； R2 is a saturated or unsaturated straight or branched chain alkyl group having 1 to 4 carbon atoms； and A is CiH2i where i is 2 to 4； B is CjH2j where j is 2 to 6； and X- is a compatible anion, f is zero to 10； M and n is an integer from 1 to 30 with the proviso that m + n is at least 2, p is 1 to 7 and g is any number from zero to 6 for each p and independent of p, and q is 1 to 7； ii. an alkyl quaternary surfactant of the formula ** (See formula) ** wherein R 1 is a saturated or unsaturated straight or branched chain alkyl group having from 8 to 22 carbon atoms； R2, R3 and R4 is independently a saturated or unsaturated straight or branched chain alkyl group having 1 to 4 carbon atoms； A is CiH2i where i is 2 to 4； B is CjH2j where j is 2 to 6； and X- is a compatible anion； f is zero to 10； P is 1 to 7 and g is any number from zero to 6 for each p and independent of p, and q is 1 to 7； iii. an alkoxylated amine of the formula ** (See formula) ** where R 1 is a saturated or unsaturated straight or branched chain alkyl group having from 8 to 22 carbon atoms； A is CiH2i where i is 2 to 4； and B is CjH2j where j is 2 to 6； f is zero to 10； M and n is an integer from 0 to 30 with the proviso that m + n is at least 1, p is 1 to 7 and g is any number from zero to 6 for each p and independent of p； iv. an amidoamine of the formula: ** (See formula) ** where R 1 is a saturated or unsaturated straight or branched chain alkyl group hav
