This work was conducted during two consecutive seasons of 2014-2015 and 2015-2016 at private orchard, El Khatatba region, Minofia Governorate, Egypt. Ten-year-old Valencia orange trees (Citrus sinensis L.) budded on Volkamer lemon (Citrus volkameriana L.) rootstock, grown in sandy soil under drip irrigation system and spaced at 5x5 m apart were chosen as plant materials to study the effect of four fertilization treatments (full dose of chemical fertilizer (100 % NPK), 25% chemical fertilizer NPK +6m3 compost/fed. +bio-fertilizer, 25% chemical fertilizer NPK +9m3 compost/fed. +bio-fertilizer, 25% chemical fertilizer NPK +12m3 compost/fed. +bio-fertilizer) and four levels of algae extract foliar spray (0, 1, 2 and 3 cm3/l) as well as their combinations on fruits yield, physical and chemical parameters as well as leaf chemical composition. Results showed that the highest fruits number/tree and fruit yield/tree were recorded by the combination between 100 % chemical fertilizer NPK and algae extract at 3cm3/l, followed by the combination between 25% chemical fertilizer NPK +12m3 compost/fed. +bio-fertilizer and algae extract at 3cm3/l. In addition, fruits weight, volume, length, diameter and peel thickness as well as fruit juice percentage were increased by using 100 % chemical fertilizer NPK combined with algae extract at 3cm3/l during the two seasons. Moreover, fruit juice TSS %, vitamin C, total sugars % and T.T.S/acid ratio were greatly improved by 25% chemical fertilizer NPK +12m3 compost/fed. +bio-fertilizer treatment supplemented with 3cm3/l algae foliar spray. Furthermore, all combinations between fertilization treatments and algae extract foliar spray increased leaf N, P and K contents as well as mature shoot total carbohydrates content, with superior for those fertilized with 100 % chemical NPK (control) or 25% chemical NPK +12m3 compost/fed. +bio-fertilizer and received algae extract foliar spray at the highest level rather than the other investigated treatments during the two seasons.