A Method for Controlling Redox Potential in Packed Soil Cores

Abstract A system was devised to maintain packed soil cores under a wide range of redox potential conditions and to measure the effect of redox potential on reduction of oxidized Fe and Mn compounds. The redox control system depended on adjusting the moisture tension or suction in the soil by use of an automatic redox sensing and a moisture tension control system. A coarse‐textured soil with rapid water film movement was necessary for good redox potential control. Adjusting the redox potential to various values ranging from aerobic to anaerobic caused Fe reduction and manganese reduction patterns similar to those obtained in earlier experiments using stirred suspensions. Oxidized Mn compounds began to be reduced to the Mn 2+ form at approximately +400 mV. Iron began to be reduced to the Fe 2+ form at approximately +200 mV.