biodegradable anionic polymers are disclosed which include recurring polymeric subunits preferably made up of vinylic and dicarboxylic monomers such as vinyl acetate or vinyl alcohol and maleic anhydride , itaconic anhydride or citraconic anhydride , or combinations thereof . free radical polymerization is used in the synthesis of the polymers , which are then hydrolyzed to replace ester groups with alcohol groups . the polymers may be complexed with ions and / or mixed with fertilizers or seed to yield agriculturally useful compositions . the preferred products of the invention may be applied foliarly , to seeds , to fertilizer , or to the earth adjacent growing plants in order to enhance nutrient uptake by the plants .