A Nano-Encapsulated Seven-Strain Microbial Bio stimulant Improves Nutrient-Use Efficiency, Soil Health and Crop Productivity Across Contrasting Soil Orders: an Integrated Laboratory, Greenhouse and Multi-Site Field Validation

Abstract

Shad AM Serroune and Olivia Mary Kessler

Conventional fertilization sustains modern crop production but operates at low efficiency: 30–50% of applied nitrogen is lost to leaching, volatilization and denitrification, while intensive cultivation drives long-term declines in soil organic matter and microbial diversity. Here we report a fully integrated 12-month laboratory, greenhouse and multi-site field evaluation of a nano-encapsulated microbial biostimulant combining a defined seven-strain consortium (Lactobacillus plantarum, Saccharomyces cerevisiae, Rhodopseudomonas palustris, Pseudomonas putida, Bacillus subtilis, Azotobacter chroococcum and Azospirillum brasilense) at ≥1×10⁹ CFU mL⁻¹ within a chitosan nanocarrier (50–300 nm; ζ ≥ +20 mV) co-loaded with molybdenum (2 ppm), silicon (150 ppm) and a 2:1:2 indole-3-acetic acid:zeatin:gibberellin package. Physicochemical characterization confirmed monodisperse nanoparticles (mean 150 ± 20 nm; polydispersity index <0.3) with component encapsulation efficiencies of 78–91% and diffusion-controlled release over 30–60 days. The platform maintained 1.2–2.8×10⁹ CFU mL⁻¹ across 4–40 °C for 12 months and through freeze–thaw cycling. In replicated randomized field trials across three soil orders, grain yield rose 14% (winter wheat, Mollisol), 22% (soybean, Alfisol) and 31% (corn under deficit irrigation, Entisol); nitrogen-use efficiency improved 28%; and a 25% fertilizer reduction was achieved without yield penalty. Nitrate and phosphate leaching fell 52% and 47% in sandy soils; acidic-soil pH rose 0.4 units while exchangeable aluminium fell 48%; microbial biomass carbon increased 35–145% and soil organic matter 0.5–0.6% within one season. Greenhouse assays showed 75–82% retention of growth and photosynthetic efficiency under drought, heat and salinity. Soil microcosms, root-architecture imaging, 16S rRNA profiling, principal component analysis and economic modeling corroborated the findings, which reproduced and, in several indices, exceeded an international benchmark. The results define soil-specific deployment pathways and establish the technology as a scalable soil-health and climate-resilience tool.

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