Nitrogen (N) demand commonly exceeds supply in young loblolly pine plantations. Soon after canopy closure, stand demand reaches a maximum while supply declines due to reduced soil temperatures, water availability, and pedoturbation. Several treatments may be applied to plantations at mid-rotation to syncronize soil supply with stand demand, including thinning the crop trees, applying N fertilizer, and controlling non-crop vegetation. A study was installed on four different site types in Louisiana to determine how thinning, fertilization, weed control, and inherent soil and site factors interact to control soil N dynamics, microbial biomass, and ultimately crop tree uptake. Results from two years of measurements will be discussed.