Straw Biochar-induced Modification of the Soil Physical Properties Enhances Growth, Yield and Water Productivity of Maize under Deficit Irrigation

Water scarcity negatively affects maize yield, whereas biochar could enhance soil physical properties and improve the growth and water productivity (WP) of maize. Thus, field experiments were conducted with three biochar addition rates of 0 t ha⁻¹ (B₀), 25 t ha⁻¹ (B₂₅), and 50 t ha⁻¹ (B₅₀) under deficit irrigation including three levels at 60% (DI₆₀), 80% (DI₈₀), and 100% (DI₁₀₀) of the reference evapotranspiration. The results showed that growth, yield and WP of maize were higher in high biochar-amended soil than non-biochar soil. The DI₁₀₀× BC₅₀ combination showed the highest values of plant height (157 and 151 cm) and stem diameter (4.6 and 4.2 cm) providing the highest yield (10.94 and 8.72 t ha⁻¹) values, in 2017 and 2018. In opposition, the DI ₆₀× BC₀ combination, showed the lowest values of plant height (157 and 151 cm) and stem diameter (4.6 and 4.2 cm) providing the lowest yield (10.94 and 8.72 t ha−1) values. While the former combination increased soil water content and total soil porosity, the latter combination reduced their value due to the increment in bulk density of the soil. The DI₈₀× BC₅₀ had the highest WP (2.61 kg m⁻³ and 2.37 kg m⁻³) values, while DI₆₀× BC₀ achieved the lowest WP (0.78 kg m⁻³ 0.74 kg m⁻³) values. The results suggest that the DI₁₀₀× BC₅₀ can guarantee improvements in plant growth contributing to the higher yield of maize. However, the DI₈₀× BC₅₀ performed better in terms of WP of maize, therefore that combination is recommended.