Proton NMR analysis reveals the influence of Biochar on the foliar metabolome of soybean and maize

Understanding how biochar influences leaf metabolome profiles at early plant growth stages remains limited, despite evidence of its effects on roots and overall plant metabolism. This study assessed whether the application of sugarcane bagasse-derived biochar (0, 1, 3, and 5% w w−1) modifies soil chemical properties and the foliar metabolic profile of soybean and maize grown under greenhouse conditions using 1H NMR spectroscopy combined with multivariate analyses (PCA, one-way ANOVA, and HCA). Biochar incorporation increased the soil pH (soybean: 5.4–6.3; maize: 5.3–6.4), base saturation (soybean: 25–47%; maize: 17–54%), Ca2+, Mg2+, and K+ levels while reducing potential acidity and aluminum saturation. In the foliar metabolome profiles, the 3% and 5% w w−1 biochar treatments led to higher accumulation of tricarboxylic acid cycle intermediates (succinate, malate, and fumarate in soybean; aconitate in maize), glucose, and phenolic compounds (chlorogenic acid and kaempferol derivatives), concomitant with reduced levels of metabolites linked to the stress response and nitrogen storage, such as asparagine, choline, trigonelline, and valine. Principal component analysis revealed a clear separation between the low and high biochar dose treatments, indicating a dose-dependent shift in metabolic pathways toward energy production, soluble carbohydrate, and antioxidant biosynthesis. These findings demonstrate that biochar directs foliar metabolism toward biochemical routes associated with improved energy efficiency and antioxidant capacity, highlighting its potential to enhance the physiological performance and sustainability of soybean and maize cultivation.