Reaction products and methods for making and using the same are provided. The reaction products particularly may include adducts of two or more reactants. The adducts particularly can incorporate a nitrification inhibitor, such as DCD. In particular embodiments, reaction products may be formed from the reaction of formaldehyde, DCD, urea, and an ammonia source. The adducts may be included in agricultural products, including fertilizer compositions and nitrification inhibitor systems. Fertilizer compositions including the adducts can be beneficial for reducing leaching of nitrification inhibitors applied to soil.