Evaluation of the impact of varied biochars produced from M. × giganteus waste and application rate on the soil properties and physiological parameters of Spinacia oleracea L.

The use of M. × giganteus in phytoremediation requires treatment of the contaminated biomass, which can be done by pyrolysis to produce biochar. Due to its potentially detrimental properties, the application of biochar in soil remediation must first be evaluated on a test plant to infer how the growth process was affected by the impact on soil parameters. The main goal of the current research was to investigate the effects of waste-derived Miscanthus biochars (from contaminated rhizomes (B1) and aboveground biomass (B2)) on soil properties and evaluate the impact of biochar doses and properties on Spinacia oleracea L. growth. It was revealed that incorporation of B1 at a dose of 5% and B2 at doses of 1, 3, and 5% increased soil organic carbon, pH, K (at 3 and 5%), and P2O5 (at 5% B2). Cultivation of S. oleracea reduced organic carbon, soil pH as a function of biochar dosage, and K, P2O5, NH4, and NO3 content in all treatments tested. The highest biomass yield was recorded at 3% B2. The photosynthetic parameters indicated that the doses of 3 and 5% B2 led to dissociation of light-harvesting complexes. Increasing the biochar dose did not necessarily increase yield or improve photosynthetic parameters. S. oleracea adapted to the initial stress by incorporating biochar and managed to establish a balance between nutrients, water supply, and light. It is recommended that the effects of biochar on the development of the target crop be evaluated through preliminary trials before biochar is applied at field scale.