Large-scale production of cellulosic ethanol from corn stover may become a reality soon. Complete stover harvest may maximize short term economic gain but could cause serious losses of soil organic matter and increases in soil erosion. Growing corn in a kura clover living mulch may permit complete stover harvest with minimal erosion hazard while providing extra organic inputs to maintain soil organic matter. We hypothesize that the living mulch may also reduce nitrate leaching, a serious concern associated with conventional corn production. Two possible causes for the hypothetical reduction are 1) reduced annual drainage beneath the root zone due to water use by the living mulch outside of the short corn growing season and 2) lower N rates required due to N fixation by the kura clover. We will present two growing seasons of data from a field experiment testing our hypothesis and examining the relative importance of these two causes.