Management strategies to improve nitrogen (N) use efficiency and reduce N loss have utilized slow or controlled release fertilizers or combined N-stabilizer products with fertilizers to reduce specific microbial transformations of N.  Another strategy, termed Integrated Nutrient Management (INM), combines microbial inoculants with fertilizers to improve nutrient use efficiency.  Although INM strategies have shown improved N uptake and yield in crops, no information was found on microbial inoculants which reduce nitrate leaching.  Using an INM approach, we conducted a 3-year field study on corn to determine if SoilBuilder AF (SBAF), a microbial product, could improve N use efficiency and reduce nitrate leaching from soil applications of urea ammonium nitrate (UAN).  Field lysimeters were established to capture water percolating through the soil to assess nitrate leaching periodically from each treatment during the season.  Treatments consisted of a full and reduced UAN application rate with or without SBAF.  The results showed that SBAF treatment significantly (P<0.05) increased corn yield from 8.1 to 16.6 bu./acre over the controls depending on the N application rate and year of the study.  SBAF significantly (P<0.05) reduced nitrate concentration in the lysimeter well water by 25% - 35% on average below the controls.  There was no correlation between lysimeter water volume and nitrate concentration.  However, there was a correlation between UAN application rate and lysimeter water N concentration, but only in the control treatments and not the SBAF treatments.  Based on 3 years of field studies, we have shown that SoilBuilder AF, when combined with UAN in an INM program on corn, can improve N use efficiency as shown by yield increases and reduced nitrate leaching.