Biochar in Controlled Environment Agriculture: Applications in Hydroponics, Vertical Farming, and Soilless Cultivation
Controlled environment agriculture (CEA), including hydroponics, vertical farming (VF), and soilless cultivation, is expanding rapidly as food production shifts toward resource-efficient and climate-resilient systems. However, conventional substrates such as rockwool, peat, coco coir, and perlite present limitations related to nutrient buffering, structural stability, and environmental sustainability. Biochar has emerged as a promising alternative substrate component due to its porous structure, surface functionality, and ability to modify root-zone conditions. This review synthesizes current knowledge on the role of biochar in controlled cultivation systems, focusing on its physicochemical properties, substrate interactions, and plant physiological responses. Biochar incorporation influences water retention, aeration, nutrient availability, and microbial activity within confined root environments, thereby improving root architecture, photosynthetic performance, crop quality, and plant uniformity. Applications across hydroponic, VF, and soilless cultivation systems demonstrate improved moisture regulation, nutrient buffering, and substrate stability. Biochar interactions with conventional media such as coco peat, perlite, and peat moss further highlight its role in engineered growing substrates. Despite these advantages, challenges remain, including feedstock variability, pH and electrical conductivity effects, lack of standardized specifications, and limited long-term performance data in recirculating systems. Emerging research areas such as engineered biochar, nano-biochar, microbial integration, and precision cultivation technologies offer opportunities to optimize biochar performance in controlled environments. Overall, biochar represents a versatile and sustainable substrate component for CEA, with potential to enhance crop productivity, substrate durability, and resource efficiency. Future research should focus on material standardization, system-specific optimization, and large-scale validation to support commercial adoption.