Potential Use of Biochar as an Amendment to Improve Soil Fertility and Tomato and Bell Pepper Growth Performance Under Arid Conditions

The aim of this study was to assess the potential use of biochar derived from olive pruning to enhance soil properties and tomato and bell pepper plant growth and yield performance in arid environments. Biochar was prepared from olive tree–pruning residues. The biochar was applied to field experiments of tomato and bell pepper plants at five application rates (0, 8, 16, 30, and 40 t ha⁻¹). Relative water content (RWC), leaf chlorophyll, and leaf nutrient (nitrogen (N), phosphorus (P), and potassium (K)) contents were measured. The total yield was determined for each treatment. Fruit nutrient contents were determined in selected fruit samples. Soil samples were collected from each treatment at the middle and end of the experiment for physical and chemical analysis. All experiments were conducted in triplicate. The application of biochar at rates of 8 and 16 t ha⁻¹ enhanced tomato and bell pepper growth; however, application of 30 and 40 t ha⁻¹ adversely affected tomato and bell pepper growth. Nutrient analysis showed that N, P, and K concentrations in leaves and fruits were higher in plants treated with 8 and 16 t ha⁻¹ of biochar than in biochar treatments of 30 and 40 t ha⁻¹. Higher biochar application rates increased soil pH and EC by 1.4% and 12.3% (8 t ha⁻¹) to 7.3% and 107.8% (40 t ha⁻¹), respectively. A biochar application rate of 8 t ha⁻¹ is recommended as an optimal rate to enhance soil fertility for tomato and bell pepper production systems in arid environments.