Evaluation of Date Palm Biochar as Oasis Soil Amendment under Saline Irrigation in Morocco

Background and Objective: Salinity is a growing problem worldwide that affects agricultural production. Biochar is considered an alternative organic amendment to improve soil physicochemical properties and fertility and mitigate salinity’s effects in Morocco’s Oases. The objective of this study was to evaluate the potential of date palm leaves biochar to mitigate the damaging effects of salinity on local lettuce seeds (Lactuca sativa). Materials and Methods: Biochar produced from date palm leaves were characterized and incorporated at different doses (1, 2, 4, 8, 16 and 32%) into an oasis soil (Ternata Oasis in Zagora, EC: 1.82 dS m^–1 1:5 soil-water-extract). Phytotoxicity of biochar amendments was evaluated by a germination test performed on local lettuce seeds in Petri dishes irrigated with the water used by local farmers with an EC of 6.96 dS m^–1. Statistical analysis was performed to evaluate the effects. Results: Biochar improved the soil that was initially poor in nutrients. Organic matter and minerals (N, K, Mg and Na) increased depending on biochar doses. Water holding capacity also increased from 21.75% (without biochar) to 49.83% (32% biochar). Concentrations of 1 and 2% biochar stimulated the germination parameters of lettuce seeds while doses of 4 to 32% negatively affected them. The addition of 2% biochar increased root and hypocotyl lengths. Conclusion: The amending oasis soil by 2% of date palm biochar leads to an improvement of its properties without having any phytotoxic effect.