Two  field experiments were conducted on sandy soil at   El-Kassasien Research Station Ismaillia  Governorate, under drip- irrigation system , during the two successive seasons  of 2004/2005 and 2005 /2006 to study the influence of N fertilizer application methods (7 N fertigation treatments) on  yield and quality of two sugar beet varieties   (Atose poly  and Loados). A split-plot design technique was used  to  carry out this trial. The 7 N fertigation treatments were : Fr₁: Applying the N fertilizer through soil + 3 hrs irrigation. Fr₂: ³/₄ hrs irrigation + 1¹/₂ hrs fertigation + ³/₄  hrs irrigation. Fr₃: 1¹/₂ hrs irrigation + ³/₄  hrs fertigation + ³/₄  hrs irrigation. Fr₄: 1¹/₂ hrs fertigation + 1 ¹/₂  hrs irrigation. Fr₅: 2¹/₄ hrs irrigation + ³/₄  hrs fertigation. Fr₆: 2¹/₄ hrs fertigation + ³/₄  hrs irrigation. Fr₇: 3hrs fertigation. The main plots  were devoted to N fertigation treatments and  the two sugar beet varieties were placed in the sub-plot units. The important results could be summarized as follow: 1. All fertigation treatments were superior to the non fertigation treatment. 2. The highest values of root, top and sugar yields and root  length were recorded  when Fr₆ treatment was applied. 3. The highest value of TSS % were obtained when Fr₅ treatment was applied, while the highest value of root diameter was obtained with Fr₃. 4. Sucross % and purity % were not significantly affected by all fertigation treatments. 5. Lados  variety surpassed Atose  poly variety for top , root and sugar yields, TSS% , root length and diameter.