Abstract: A surface-modified solid fertilizer product is produced by preparing a mixture of a modifier, a water-soluble calcium salt, and water. The modifier is desirably a nitrification inhibitor such as dicyanodiamide and the calcium salt is desirably calcium chloride. A solid fertilizer is prepared, preferably in granular form. The fertilizer has a component reactive with calcium to produce a water-insoluble precipitate. The mixture is coated onto the solid fertilizer, and the solid fertilizer having the mixture coated thereon is dried. The calcium salt reacts with the reactive component of the fertilizer to produce an insoluble binding agent that binds the modifier to the surface of the fertilizer particles.