Microbial biofertilizers offer a sustainable alternative to reduce inorganic fertilizer inputs in intensive vegetable production. While rhizobia are traditionally associated with legumes, their co-inoculation with native rhizobacteria for non-leguminous crops like tomatoes remains under-explored. This study aimed to isolate native rhizobacteria compatible with Bradyrhizobium diazoefficiens NE1-65 and evaluate their combined effect on the tomato plant (var. max F1) under reduced inorganic fertilizer rates. From the initial eighteen isolates screened on nitrogen-free media, and solubilization assays of phosphorus and potassium, three isolates (RM-8, RM-17, RM-18) were found compatible with B. diazoefficiens NE1-65. Isolate RM-17 (tentatively identified as Aureimonas sp. based on 16S rRNA gene sequence) was selected for its high K-solubilizing capacity (KSI = 8.60). Then, a 90-day growth trial compared various fertilizer application rates (0, 25, 50, 75, and 100%) with and without the bacterial consortia. The 75% fertilizer rate plus the consortia significantly outperformed the 100% fertilizer rate alone. Specifically, it increased plant height (11.57%), fruit diameter (9.23%), fruit number (53.90%), and fruit weight (16.15%). These findings demonstrate that the RM-17 and B. diazoefficiens NE1-65 consortia can partially substitute inorganic fertilizers while significantly enhancing tomato growth and yield, highlighting its potential application for sustainable tomato production systems.

This study investigates the impact of selected soil parameters and integrated fertilizer formulations on the productivity of three legume crops—mung bean, soybean, and cowpea—in order to identify the optimal strategies to maximize yields through reduced nitrogen and bio-augmentation. A five-year experiment composed of 2-year pot trials (2019–2020) and 3-year field trials (2022–2024) was conducted to assess the changes in soil parameters (N, P, K, OM, pH) and yield response of crops with varying amounts (1, 2, 4 kg) of Bradyrhizobium-based biofertilizer combined with a 25–50% reduction in mineral N fertilizer. The biofertilizer was composed of locally isolated strains, which were genetically identified in our previous reports as B. elkanii NE1-6, NE2-1, B. diazoefficiens NE1-65, Bradyrhizobium sp. NE1-19, NE1-34, and NE2-3. The results indicated that the amount of K strongly influenced yield increase for soybean (r = 0.85, p < 0.05) and mung bean (r = 0.67, p < 0.05), while the amount of N had the greatest influence on cowpea (r = 0.60, p < 0.05). Soybean yield was maximized with a 50% reduction in N fertilizer (20 kg N) combined with 2–4 kg biofertilizer, while cowpea and mung bean achieved increased yields at 25% reduced N fertilizer combined with 2–4 kg biofertilizer. This study confirms the viability of integrating Bradyrhizobium-based biofertilizer with a 25–50% reduction in mineral N fertilizer without yield loss by harnessing the efficient N-fixation ability of the strains in the consortium.