The superabsorbent polymers (SAPs) were synthesized by grafting copolymerization of acrylic acid and acrylamide onto starch by using gamma-ray radiation technique and poly(ethylene glycol) (PEG) as a crosslinker. The samples were characterized by IR spectroscopy. The effect of various synthetic parameters such as irradiation dose, irradiation dose rate, monomer concentration, monomer/starch ratio, and PEG content were studied. The effects of different drying methods on water absorbency of the SAPs were also studied. The experimental results showed that the water absorbency of the SAPs depends largely on the specific conductance of water when the specific conductance is below 500 mus/cm. The water retention of sand and soil was enhanced by using the SAPs. Effects of the SAPs on the germination of seeds and growth of young plants were investigated. (C) 2004 Wiley Periodicals, Inc.