A series of novel copolymer superabsorbents based on acrylamide, sodium allylsulfonate, sodium acrylate, and N,N’-methylenebisacrylamide were prepared by copolymerization. The resulting superabsorbents have a fast swelling rate. The experimental results show that absorbency increases to a maximum as the cross-linking increases, but an excess of cross-linking leads to a swelling decrease. Their water retention was observed at pressures of 1-10 kg/cm2 and temperatures of 60 and 100-degrees-C, respectively. The water retention of soil has been enhanced by using the poly(acrylamide-sodium allylsulfonate-sodium acrylate) superabsorbent; its use for bean growth was also investigated.