Fertilization is needed to replace nutrients removed from pine straw plantations, but tree response to fertilization could be influenced by stocking rate. Our objective was to determine effects of three N fertilizer sources on loblolly pine (Pinus taeda L.) growth and pine straw yield as a function of stocking rate (trees ha-1, TPH) at about midrotation (12-14 years post-planting). Commercial mineral fertilizer (CF), poultry litter (PL, 5.4 Mg ha-1), and pelletized poultry litter (PPL, 4.6 Mg ha-1) were applied once in April 2006 at 0 (control) and 200 kg ha-1 of N at plantation stocking rates of 2300, 1200, and 970 TPH near Booneville, AR. Basal area (range 32.6 to 42.8 m2 ha-1) was very high and did not respond to fertilization, and pine straw yield also did not consistently increase with fertilization compared to the control. Concentrations of pine straw N and foliar N increased with fertilization, especially with CF compared to litter. Topsoil NO3 --N and NH4 +-N were greater for CF than PL and PPL 3 mo after fertilization, but responses ≥ 9 mo after application did not differ from the control. While the plantations were able to acquire N, overstocking seemed to constrain N utilization for increased BA or foliage production. Thinning should improve tree growth and pine straw yield responses to fertilizer applied at mid-rotation.