The amount of water retained by a sandy soil against a 0.01 MPa pressure increased by 23 and 95% by adding small amounts (0.03 and 0.07% by weight, respectively) of a polymer to the soil. However, the polymer did not significantly increase the quantity of water released from the soil by increasing the pressure from 0.01 to 1.5 MPa. The additional amount of water retained by the soil due to the presence of polymer was completely available to soybean plants grown in pots. Consequently there were substantial increases in water use efficiency of soybean plants grown in soils treated with 0.03 (12) and 0.07% (19) polymers
