Biochar-mediated enhancement of soil functionality and drought resilience in maize under deficit irrigation

Abstract

Drought stress and declining soil organic matter are critical constraints on cereal production in arid and semi-arid agroecosystems, impairing soil water dynamics and plant physiological functioning. This study evaluated the effects of seaweed-derived biochar applied at 0, 2.5, 5 and 7.5% (w/w) under two deficit irrigation regimes (0.55 and 0.70 of field capacity, FC) on soil–plant water relations, physiological performance and yield of maize ( Zea mays L.). Drought stress significantly reduced leaf area (22–37%), stomatal conductance (24–51%), water use efficiency (16–18%), harvest index (39–66% at 0.55 FC), plant height (29–59%) and grain yield (39–63%), whereas the leaf greenness index increased (9–19%). Biochar amendment improved soil–plant interactions under deficit irrigation, enhancing leaf area, stomatal conductance (10–19%) and greenness index (7–40%). The 2.5% treatment was the most effective, increasing water use efficiency by 27%, biomass production and plant height (17%). Higher rates (5 and 7.5%) conferred no additional benefit and in some cases reduced grain yield and 1000-grain weight; these declines were not attributable to salinity but may reflect altered soil physicochemical equilibrium and nutrient dynamics. Moderate application of seaweed-derived biochar therefore enhances soil functionality and mitigates drought-induced productivity losses in water-limited maize systems.