A novel agricultural formulation includes at least one finely divided solid water-insoluble material and at least one novel dispersant containing a polymer synthesized from first and second comonomers. The first comonomer is an .alpha.,.beta.-unsaturated oxyacid or anhydride, and the second comonomer is an olefin having at least one polymerizable double bond. Also disclosed is a method for dispersing a finely divided solid insoluble material, in particular, an active water-insoluble agrochemical principal, in an aqueous solution; a method for treating a substrate with such a material or principal; and a method of making an agrochemical formulation, where the methods are based on application of the novel dispersant to the preparation of aqueous dispersions of the solid material and agrochemical principal.