A composition for preventing the caking of solid fertilizers comprising - at least a component (a) which comprises a mixture of at least one or more quaternary mono-, di- or tri-ester ammonium compounds of formula,, wherein in formula I1, I2 and I3 R 2 and R 3 each independently represent -H or -OH; X 1 represents a hydroxyalkyl group containing 1 to 4 carbon atoms, an alkyl group containing 1 to 4 carbon atoms or an alkyl group containing one aromatic group; R 1 is a linear or branched alkyl containing 5 to 23 carbon atoms or a linear alkenyl group containing 5 to 23 carbon atoms and from 1 to 3 double bonds; L represents a - (OCH 2 CH 2) a -(OCHR 4 CH 2) b - group, wherein R 4 represents an alkyl group containing 1 to 4 carbon atoms, a represents a number within the range of 0 to 20, b represents a number within the range of 0 to 6, and the sum of a+b represents the average alcoxylation degree which corresponds to a number from 0 to 26; m, n and p each independently represent a number within the range from 1 to 4, q represents a number within the range from 0 to 26 and A - represents an anion. Wherein in said component (a) the sum weight percentage of di- and tri-quaternary ester ammonium compound ( and) is from 75 to 100% wt, based on the weight of component (a) - at least a component (b) which comprises at least a solvent, wherein the solvent is selected from mineral oils, paraffins and waxes derived from petroleum and vegetal and animal fats and oils, and wherein the solvent content is 50% wt or more, based on the total weight of the composition. - at least a component (a) which comprises a mixture of at least one or more quaternary mono-, di- or tri-ester ammonium compounds of formula,, wherein in formula I1, I2 and I3 R 2 and R 3 each independently represent -H or -OH; X 1 represents a hydroxyalkyl group containing 1 to 4 carbon atoms, an alkyl group containing 1 to 4 carbon atoms or an alkyl group containing one aromatic group; R 1 is a linear or branched alkyl containing 5 to 23 carbon atoms or a linear alkenyl group containing 5 to 23 carbon atoms and from 1 to 3 double bonds; L represents a - (OCH 2 CH 2) a -(OCHR 4 CH 2) b - group, wherein R 4 represents an alkyl group containing 1 to 4 carbon atoms, a represents a number within the range of 0 to 20, b represents a number within the range of 0 to 6, and the sum of a+b represents the average alcoxylation degree which corresponds to a number from 0 to 26; m, n and p each independently represent a number within the range from 1 to 4, q represents a number within the range from 0 to 26 and A - represents an anion. Wherein in said component (a) the sum weight percentage of di- and tri-quaternary ester ammonium compound ( and) is from 75 to 100% wt, based on the weight of component (a) R 2 and R 3 each independently represent -H or -OH; X 1 represents a hydroxyalkyl group containing 1 to 4 carbon atoms, an alkyl group containing 1 to 4 carbon atoms or an alkyl group containing one aromatic group; R 1 is a linear or branched alkyl containing 5 to 23 carbon atoms or a linear alkenyl group containing 5 to 23 carbon atoms and from 1 to 3 double bonds; L represents a - (OCH 2 CH 2) a -(OCHR 4 CH 2) b - group, wherein R 4 represents an alkyl group containing 1 to 4 carbon atoms, a represents a number within the range of 0 to 20, b represents a number within the range of 0 to 6, and the sum of a+b represents the average alcoxylation degree which corresponds to a number from 0 to 26; m, n and p each independently represent a number within the range from 1 to 4, q represents a number within the range from 0 to 26 and A - represents an anion. - at least a component (b) which comprises at least a solvent, wherein the solvent is selected from mineral oils, paraffins and waxes derived from petroleum and vegetal and animal fats and oils, and wherein the solvent content is 50% wt or more, based on the total weight of the composition.