Determining the characteristics and potential of plantbased biochars to reduce copper uptake in maize

Metal contamination problems have become common everywhere with several known cases of metal toxicity in the agriculture sector. Metals including copper (Cu) are important to plant metabolism in trace amounts; however, excessive amounts can cause toxicity to the plants. The biochars have potential to absorb these trace elements in soil. A study was conducted to determine the characteristics and potential of different plant-based biochars to control Cu uptake and influence on the growth of maize (Zea mays L.). Five biochars from different agricultural waste materials, such as rice husk (RH1 and RH2), empty fruit bunches (EFB1 and EFB2) and oil palm kernel (OPK), were selected in the study. Each biochar was applied at 20 t·ha-1 on Cu contaminated soil, and maize was grown for 56 days in pots with 10 kg of acidic soil. The rice husk biochar (RH1) with a substantial number of heterogenic functional groups (alcohols and phenols, carboxylic acids and derivatives, amines, saline, alkynes) on its surface and more porous structure was able to retain more nutrients. It also give the best results in terms of reducing the Cu concentrations (1.61 mg-kg-1) in plants and plant uptake (10.15 µg·pot-1). Other than that, the highest plant growth parameters were also perceived in rice husk biochar applications. Hence, RH1 biochar had the most promising results in terms of controlling the plants Cu uptake and improved maize plant growth.