The present study was conducted during 2015, 2016 and 2017 seasons to study the effect of replacing mineral nitrogen fertilization by organic nitrogen and biofertilizers on Costata persimmon trees, under calcareous soil conditions. The treatments consist of T1 (100% mineral nitrogen), T2 (75% mineral nitrogen + 25% organic nitrogen), T3 (50% mineral nitrogen + 25 % organic nitrogen + biofertilizer), T4 (25% mineral nitrogen + 50 % organic nitrogen + biofertilizer) and T5 (100% organic nitrogen). Rice straw compost was used as a source of organic nitrogen and N2-fixing free living bacteria namely Azotobacter chroococcum and Azospirillum lipoferum as a source of biofertilizers. The obtained results can be summarized as follows: Treatment of 50% mineral nitrogen + 25% organic nitrogen with biofertilizers gave the highest values of vegetative growth in terms of shoot number/branch, shoot length, leaf numbers per shoot and leaf area of Costata persimmon trees compared to mineral nitrogen fertilizers only. Moreover, treatments included organic and biofertilizers were raising leaf content values of chlorophyll, N, P, K, Ca, Fe, Mn and Zn especially in the second season. As for yield, treatment of 50% mineral nitrogen + 25% organic nitrogen + biofertilizer and 75 % mineral nitrogen + 25% organic nitrogen produced the highest yield in terms of number of fruits/tree, weight (kg/tree) and total yield (ton/feddan). All treatments led to improving properties of fruit quality especially treatment of 50% mineral nitrogen +25% organic nitrogen +biofertilizers. Also, treatments containing organic and biofertilizer led to reducing nitrate and nitrite values in fruit juice comparing with 100% mineral nitrogen fertilizer.
Conclusively, this treatment is recommended: (50% mineral nitrogen +25% organic nitrogen +biofertilizers). This treatment gave the best growth, yield, fruit quality and nutritional status of Costata persimmon trees.