Biochar-based Controlled-release Fertilizers: Smart Nutrition for Sustainable Agriculture

Abstract

Biochar-based controlled-release fertilizers (BCRFs) have emerged as a smart and sustainable alternative to conventional chemical fertilizers, addressing the critical challenges of low nutrient use efficiency and environmental pollution. This review systematically synthesizes the paradigm shift of BCRFs from passive nutrient carriers to intelligent regulators in soil‑plant systems. A structured literature search was performed from January 2015 to April 2026 in Web of Science, Scopus, and Google Scholar using keywords such as “biochar‑based controlled‑release fertilizers”, “smart nutrition”, and “nutrient use efficiency”. A two‑stage screening (title/abstract followed by full text) and systematic data extraction were employed, prioritizing studies with robust experimental designs and field‑scale validations. The findings demonstrate that BCRFs significantly enhance crop yield (by 15–30%), nutrient use efficiency (up to 58.8% for N), soil water retention, and carbon sequestration, while reducing nutrient leaching (by 69–88%), greenhouse gas emissions (up to 66% for N₂O), and cadmium accumulation in crops (by 80%). Key mechanisms include physical barrier effects, chemical interactions (hydrogen bonding, complexation), and stimuli‑responsive release (pH, moisture, temperature). Advanced formulations (e.g., ethylcellulose/soybean wax coatings, nano‑enabled carriers, high‑pressure impregnation) further improve release kinetics. However, performance varies with feedstock, pyrolysis conditions, and coating materials. Challenges remain in long‑term field validation, standardized life‑cycle and techno‑economic assessment, ecological risk evaluation, and scalable production. Future directions include multi‑stimuli responsive systems, AI‑driven optimization, and interdisciplinary collaboration. This review provides an engineering‑to‑agronomy framework to guide researchers, policymakers, and farmers toward climate‑smart deployment of BCRFs.