A slow release NPK fertilizer formulation was prepared via insitu free radical graft polymerization of salep with an acrylic acid (AA) monomer in the presence of montmorillonite (MMT) and fertilizer. Evidence of component interactions, morphology, thermal properties, and fertilizer incorporation into hydrogel nanocomposite fertilizer formulation was obtained using FTIR, XRD, TGA, and SEM techniques. The swelling behavior of hydrogels in various pH and saline solutions was investigated. In addition, the water retention capability of loamy sand soil having the prepared fertilizer formulation was evaluated. The results showed that the synthesized hydrogels have pH and salt sensitive swelling behaviors as well as good water retention properties. Fertilizer release studies also showed that the presence of MMT caused the formulation system to liberate the nutrient in a more controlled manner. Finally, these good characteristics showed that these formulations are potentially applicable for agricultural and horticultural purposes.