Nitrate reduction in soil may result from heterotrophic denitrification, autotrophic denitrification, or competing systems involving microbial iron reduction. Few studies actually follow changes in soil iron during nitrate reduction under native soil carbon and iron conditions. Here we investigate nitrate reduction in a Sadler silt loam soil (fine-silty, mixed, mesic, Glossic Fragiudalf), typical of agricultural producing regions in Western Kentucky. Nitrate was added to soil subjected to different treatments, and changes in Fe were followed in stirred-batch experiments. Nitrate reduction was described well by Michaelis-Menten kinetics and tightly coupled with Fe(II) oxidation. The contribution of Fe(II) oxidation to nitrate reduction was favored under conditions of low initial nitrate concentration and in soil slurries amended with tungstate. Where concomitant nitrate reduction and Fe(II) oxidation occurred, dissolved Fe(III) was produced. Pathways to account for the experimental results are proposed.