Effect of Integrated Mineral and Bio-fertilizers on Onion (Allium fistulosum) Growth and Soil Nutrient Status

Onion (Allium cepa L.) is an important crop in Egypt that requires fertilizer to improve yield and soil health in low-organic-matter soils. At Damanhour University, experiment farm at Agriculture faculty, this study assessed the effects of mineral fertilizer and bio-fertilizers (Nitrobeine, Phosphorene) combinations on soil fertility, growth, and nutrient content of green onions (Allium fistulosum L.) in loamy sand soil during the 2022–2023 and 2023–2024 seasons. Using a Completely Randomized Design with three replicates, treatments included control (CK), NPK, Nitrobeine (bioN), Phosphorene (bioP), mixed bio-fertilizers (bioN-P), NPK&bioN, NPK&bioP, NPK&bioN-P, 0.5NPK&bioN-P, and 0.75NPK&bioN-P. Vegetative growth characteristics, plant chlorophyll content (SPAD), plant and soil nutrients contents were measured. Fresh weight of the plant (33.03 g), dry stem weight (8.97 g), plant content of N (3.18%), K (3.43%), soil content of N (26.95 ppm), P (11.05 ppm), and K (119.25 ppm) were all maximized by the NPK&bioN-P treatments. Similar result was achieved with fresh weight (32.23 g) and root/leaf growth with application of the 0.5NPK&bioN-P treatments, suggesting that yield was maintained at 50% lower NPK when combined with bio-fertilizers. While soil P grew (6.93, 14.67 and 13.60% consecutively) with bio-fertilizers-only treatments (bioN, bioP, and bioN-P). For increasing onion productivity in Egypt, integrated nutrition management provides a sustainable approach, especially for NPK&bioN-P and 0.5NPK&bioN-P.