There is provided a smart release potash fertilizer granule comprising a potash core; an extended release layer covering the potash core, wherein the extended release layer comprises water-swellable copolymeric nanoparticles and at least one water-soluble organic acid or water-soluble organic carboxylate salt; a controlled release layer covering the extended release layer, wherein the controlled release layer comprises water-swellable copolymeric nanoparticles; and an anticaking layer covering the controlled release layer, wherein the anticaking layer comprises water-insoluble copolymeric nanoparticles.