Abstract
Biochar as an eco-friendly and low-cost product has the potential for modification to improve its functionality. The application of modified biochar is a new approach that can improve soil properties, quality, and productivity of plants, thereby helping sustainable agriculture. The focus of the recent studies has dealt with methods for improving the function of biochar. Biochar can be modified to enhance its physicochemical properties (such as bulk density, cation exchange capacity, specific surface area, and porosity) and nutritional value. This review provides crucial and summarizing information about the classification of biochar modification techniques for agricultural application and a comparison of pristine and modified biochar function on soil fertility and plant production. There are several approaches for modification of biochar, which can be divided into four main categories: chemical, physical, enriched with minerals, and nanocomposites. The modified biochar could be more appropriate for poor-nutrient soils and has a high adsorption capacity and potential for different pollutants immobilization. Further research is needed to determine the best methods of biochar modification with short-term and long-term effects on soil fertility and plant growth under different environmental conditions.