Impact of Organic and Chemical Fertilizers with Biochar on the Antioxidant System of Cabbage Plants Grown in Contaminated Soil

A pot experiment was carried out in Al-Rashidiya District, Baghdad Governorate according to RCBD design during the winter growing season (2024-2025) as a factorial experiment with three replicates. The study included two factors: the first is fertilizer types (animal manure, NPK fertilizer, and control treatment (without adding fertilizers), while the second is the addition of biochar 2% and without addition to determine their effect on enzymatic antioxidants (GPX, SOD, CAT POD) and non-enzymatic antioxidants (proline), and MDA in the cabbage plant grown in soil contaminated with cadmium, lead, and copper. The results showed a significant decrease in the concentrations of GPX, SOD, CAT POD when adding 2% biochar with an average of 0.0516, 0.2581, 0.184, 0.2272 absorption unit min −1 g −1 , respectively. The concentration of proline decreased when biochar was added and MDA with an average of 1.977 and 2.501 μg g −1 , respectively. As for fertilizers, animal manure significantly reduced the concentrations of GPX, SOD, and CAT POD with an average of 0.0628, 0.2612, 0.198, 0.2107 absorption unit min −1 g −1 , respectively, and reducing the concentration of proline and MDA by 2.063, 2.587 μg g −1 , respectively, followed by NPK fertilizer compared to the control, which recorded the highest average. The interaction between biochar and fertilizers had a significant effect in most of the characteristics.