Soil microbial communities are known to respond to different soil management practices. In this study, we determined the influence of irrigation and fertilization on soil microbial communities in a seven-year-old loblolly pine plantation. Field experiment plots were established in 2000 on a Blanton sandy soil near Aiken, South Carolina. The experiment was arranged in a randomized complete block factorial design with three blocks and irrigation and fertilization as factors. Soil samples (0-15 cm) were collected from different positions (North, Center and South) with respect to planting rows on a monthly basis beginning in February, 2006. The soil samples were analyzed for soil microbial biomass carbon and phospholipid fatty acid (PLFA) contents. The preliminary results show that soil microbial biomass carbon were significantly higher (P=0.05) in fertilized, irrigated, and fertilized-irrigated plots than in control plots; however, there was no significant difference among sampling positions. Soil microbial biomass carbon ranged from 118.7 to 203.5ėg per gram of soil during the sampling period. Soil microbial communities as indicated by PLFA profiles will be assessed.