Organic nitrogen fertilization minimizes requirement of inorganic fertilizers and improves growth and yield attributes of superior grapevines

Purpose: Nitrogen (N) fertilization is the essential nutrient element that limits crop yields before any other element. However, excessive use of N fertilization often leads to economic loss and quality deterioration of the yield. Materials: In the present study, superior grapevines were fertilized with chemical N fertilizer, chicken manure, or biofertilizer (Nitrobeine) over three seasons (2018, 2019, and 2020) to quantify N usage from different sources. Results: The current study’s findings show that N in the mineral form at 60% to 80%, organic and biofertilizers at 20% to 40% was very effective in improving all growth characteristics and yield when compared to using nitrogen completely in mineral form or reducing the percentages of mineral to 40%. Reducing the ratios of mineral nitrogen from 100% to 40% and at the same time increasing the proportions of organic and biofertilizers from 0.0 to 60% caused a gradual increase in the improved berry quality, raising in TSS, % reducing sugars, TSS/acid ratio and decreasing in total % acidity in berries. Conclusions: To improve the yield of Superior grapevines quantitatively and qualitatively with minimum chemical N, it is advisable to supply the vines with the suitable nitrogen (72.0 g N/vine/season) as mineral N (ammonium nitrate) at 60%, organic (chicken manure) at 20% and bio-fertilizers (nitrobeine) at 20%. Thus, replacing 40% of mineral fertilizers with organic and bio-fertilizers can be recommended for producing organic berries.