Biofertilization using Azotobacter chroococcum (B₁), Azospirillum brasilense (B₂) and Bacillus megaterium (B₃), were assessed vs.  Mineral-N fertilization using ammonium sulphate with 2% ¹⁵N atom excess on sunflower grown on a virgin sand during 2014 summer season. Plants grew for 45 days. The highest plant height (64.87 cm) with an increase about 93.6% over the non-fertilized was given by the Azospirillum bacteria combined with the high N rate (N₃B₂). Total chlorophyll ranged from 17.8% by (N₂B₁) to 34.9% by (N₃B₀). The highest dry matter yield of 44.20 kg ha^-1 was by N₃B₀. The highest N uptake was given by plants receiving high N without biofertilization (N₃B₀) with an increase 141.4%. The highest fertilizer N recovery of 18.45% was by high N without biofertilization (N₃B₀) with an increase 99.7%.