Optimization of peapod peel biochar amendment for sustainable agriculture by surface response methodology towards water-food-environment nexus

Valorization of food waste to biochar offers economic and environmental opportunities for sustainable agriculture production. Peapod (Pisum sativum) peel is a high-content lignocellulose vegetable waste and was used in this study to produce biochar through pyrolysis temperatures of 350, 450, and 550 °C, with a heating rate of 5 °C/min for 30 min and thereafter characterized for its various properties. The biochar produced at 350 °C, exhibiting the best soil amendment properties was used for pot testing with mung bean (Vigna radiata). The optimization of plant growth, soil water retention capacity, and microbial activity were determined using response surface methodology (RSM) with three design factors: (a) biochar loading rates (0 %, 0.5 %, and 1 %), (b) temperature (30–40 °C), and (c) quantity of water supplied (50–60 mL/day). The results showed that applying 0.5 % biochar with a water supply of 55 mL/day at 35 °C resulted in optimal responses for seed germination, plant height, and leaf development. Applying 1 % biochar with a water supply of 55 mL/day at 35 °C showed optimal responses for leaf area and leaf chlorophyll content. Stomatal conductance and catalase activity showed optimal responses for 1 % biochar applied with a water supply of 60 mL/day at 40 °C. Urease activity and water retention capacity showed optimal responses when 1 % biochar was applied with a water supply of 60 mL/day at 30 °C, respectively. This study demonstrates the potential use of peapod peel biochar in water-food-environment nexus, with a lower dose and lesser volume of water demand.