T􀀩o field e􀀪periments 􀀩ere conducted during 2􀀚􀀛2 and 2􀀚􀀛3 seasons at the Agricultural E􀀪perimental Farm
of Suez Canal University at Ismailia in the first season and El-Manayf district in the second season in Ismailia
Governorate to study the effect of four nitrogen fertilization treatments namely 2􀀰, 4􀀰, 􀀱􀀰 and 2􀀰 Kg N/fad plus
biofertilizer 􀀶Cerealin􀀷 as 􀀩ell as three plant densities namely 4􀀱􀀱􀀱􀀱, 3􀀰􀀚􀀚􀀚 and 28􀀚􀀚􀀚 plants/fad resulted by so􀀩ing
sunflo􀀩er in ridges 􀀱􀀚 cm in 􀀩idth and hill spacings 􀀛􀀰, 2􀀚 and 2􀀰 cm on sunflo􀀩er Sakha 􀀰3 variety in sandy soils.
Increasing nitrogen fertilization up to 􀀱􀀰 Kg N/fad significantly increased all gro􀀩th characters, yield attributes as 􀀩ell
as seed, biological and oil yields/fad. Applying biofertilizer 􀀶Cerealin􀀷 plus 2􀀰 Kg N/fad significantly surpassed 2􀀰 Kg
N/fad alone in the above characters. Decreasing hill spacing up to 􀀛􀀰 cm significantly increased seed, biological and oil
yields/fad. There 􀀩as significant interaction bet􀀩een nitrogen fertilization and plant density on seed, biological and oil
yields/fad. The highest seed, biological and oil yields/fad 􀀩ere obtained by adding 􀀱􀀰 Kg N/fad under dense planting of
4􀀱􀀱􀀱􀀱 plants/fad.