Superabsorbents were synthesized by solution polymerization using acrylic acid (AA)as monomer,natural products such as montmorillonite(MMT),potassium humate(HA),carboxymethyl cellulose(CMC)as the additives.They were characterized by fourier transform infrared spectroscopy,scanning electron microscopy and thermogravimetry/differential scanning calorimetry.The effects of polymeric parameters such as MMT,HA,CMC and crosslinker content on the water absorbency were investigated.The maximum absorption ratio of the resulting composites in distilled water and 0.9% NaCl solution was up to 801 and 87 times,respectively.The composites were loaded with KH2PO4 and their potential for controlled release of this salt was investigated,the results showed that MMT and moderate crosslinking could improve their loading percent for KH2PO4 and reduce the release rate of KH2PO4 effectively,HA could improve the water absorbency of the superabsorbents,but it had little effect on the load and slow release of KH2PO4.