Integrated Microbial Inoculation Enhances Tomato Productivity and Soil Nutrient Availability under Reduced Fertilization in Vertisol

Abstract

Beneficial soil microorganisms offer a promising approach for enhancing soil fertility and nutrient availability while improving crop productivity and reducing dependence on mineral fertilisers. A field experiment was conducted during the Rabi season of 2023–24 at the Research Farm of the Vegetable Research Centre, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani, Maharashtra, India, to evaluate the effects of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on tomato productivity and soil nutrient availability under Vertisol conditions. Twelve treatments comprising 75% of the recommended dose of fertilisers (RDF) in combination with individual or combined microbial inoculants, applied either as a seedling treatment or through soil application, were evaluated in a randomised block design with three replications. The treatment comprising 75% RDF + AMF + Pseudomonas fluorescens + Bacillus megaterium + Trichoderma viride applied through soil application (T₁₂) recorded the highest fruit yield (371.53 q ha⁻¹) and dry matter yield (46.09 q ha⁻¹), representing increases of 25.88 and 37.91% over 100% RDF, respectively. At 95 days after transplanting, T₁₂ also maintained the highest soil available N (204.20 kg ha⁻¹), P (24.90 kg ha⁻¹) and K (798.15 kg ha⁻¹), corresponding to increases of 23.36, 37.49 and 14.73%, respectively, over 100% RDF. The corresponding increases over the absolute control were 46.01, 82.95 and 31.74%. The combined soil-applied consortium consistently produced greater yield and soil nutrient availability than the corresponding seedling application, although the two application methods were statistically comparable for several attributes. Among individual microbial treatments, soil application of AMF was the most effective. The findings demonstrate that AMF–PGPR integration with 75% RDF can improve tomato productivity and maintain higher soil nutrient availability while reducing mineral fertiliser input by 25% under Vertisol conditions.