Trichoderma Mobilizes Phosphorus and Cobalt While Excluding Sodium in the Foliar Ionome of High-Andean Grasses Enriched With Biochar

Abstract

Acidic high-Andean soils constrain grassland productivity by limiting nutrient availability and altering plant ionomic balance. Biochar inoculated with plant growth-promoting microorganisms has emerged as a promising strategy to mitigate these constraints; however, the extent to which microbial identity modulates plant nutrient acquisition remains poorly understood. This study evaluated the effects of Trichoderma sp., Bacillus sp., and Pseudomonas sp. as inoculants of guinea pig manure–derived biochar on soil pH and the foliar ionome of Carex sp., Dactylis glomerata, Festuca dolichophylla, and Lolium perenne in a high-Andean Andisol (4150 m a.s.l.). A randomised complete block design (4 × 4 factorial, three replicates) was used. Biochar (20 t ha⁻¹) was applied at establishment, and microbial inoculants (5 L ha⁻¹) were applied at sowing and during crop development. Foliar elemental concentrations were determined by MP-AES and analysed using ANOVA and multivariate approaches. Biochar significantly increased soil pH (p < 0.001). Ionomic responses depended on microbial identity: Trichoderma sp. enhanced P and Co accumulation while reducing Na (p < 0.05), indicating coordinated nutrient regulation. Micronutrients (Fe, Mn, Cu) were primarily species-driven. These findings demonstrate that microbially functionalized biochar can selectively reconfigure plant ionomes, supporting microbiome-assisted strategies to improve nutrient efficiency and resilience in acidic agroecosystems.