BIOCHAR PARTICLE SIZE EFFECT ON SORPTION OF PLANT NUTRIENTS

Abstract

The pyrolysis of biomass into biochar can served as nutrient absorbent in soil to counter excessive leaching problem commonly faced by agriculture sector in tropical region. The present study investigated the particle size of biochar on the sorption of ammonium N (NH 4+ -N), nitrate N (NO 3- -N), phosphate P (PO 43- ), and iron (Fe 3+ ). Four biochars were produced from oil palm empty fruit bunch (EFB), oil palm kernel shell (KRN), rice husk (RH), and bamboo (BMB), which sieved into two groups with particle size of 1-2 mm and <0.3 mm. Biochar physical and chemical properties were determined. The ability of biochars to adsorb NH 4+ followed: BMB > RH > EFB while no sorption was observed in KRN. The sorption characteristics of NH 4+ were well fitted to the Freundlich isotherm model. Overall sorption of NO 3 - favours fine particle and were well-fitted into Langmuir model followed the maximum sorption capacity of: BMB > EFB > KRN > RH. Sorption of PO 43- on the other hand performed poorly among all tested biochar while sorption of Fe 3+ were generally favourable in fine particle and best-fitted in Langmuir model with the maximum sorption capacity followed: EFB > RH > KRN > BMB.