Improved gypsum fertilizer compositions are provided by coating of naturally-occurring or synthesized gypsum with low pH maleic-itaconic copolymers. The preferred copolymers are aqueous dispersions of acid or partial salt maleic-itaconic copolymers, and are applied by spraying or other means onto the surface of gypsum and allowed to dry. The copolymer coatings increase the solubility of sulfate and Ca ions from the gypsum, allowing accelerated plant availability and uptake of such nutrients.