Abstract: Phenolic polymers are prepared by dissolving one or more organic phenols along with sodium periodate in aqueous base at pH 8-11, and allowing the mixtures to stand between 35 and 80.degree. C. for a period of 30 minutes to 100 hours. One or more inorganic compounds or salts is added and the solution is allowed to stand at room temperature between 2 and 48 hours. Salt molecules as well as starting compounds and other low molecular-weight materials below about 500 to about 10,000 daltons are removed from the product solutions. Purified phenolic polymers are prepared in concentrated aqueous solution or in dried powder form in a final step if necessary. The resultant phenolic polymers exhibit physicochemical properties strongly resembling those of typical commercially-available natural soil extracts.