Production and characterisation of biochar from different farm wastes

Abstract

Three different carbon-rich materials called biochars were produced from three different agricultural wastes using slow pyrolysis technique. The abundance of these wastes (maize cobs, maize stovers and cocoa pod husks) in most farms in Nigeria informed their choice. In this study, the biochars produced were characterized to determine their inherent nutrient potentials as soil amendments for high crop productivity. The percentage mass of biochars obtained were: maize cobs 27.6%, maize stovers 26.0% and cocoa pod husks 22.3% at 332°C, 361°C and 500°C temperature respectively. The highest carbon content (511.1 g kg^-1) and total nitrogen (12.1 g kg^-1) were obtained from maize stovers biochar, while cocoa pod husks gave the least values. Highest pH (11.98), moisture content (14.0%) and phosphorus (1150.0 mg kg^-1) were however obtained in the biochar from cocoa pod husks. We concluded that cocoa pod husks, maize cobs and maize stovers are feedstocks for making biochars of different physical forms and properties and these biochars are potential sources of valuable soil amendments in a humid tropical soil environment.

Keywords: Biochar, charcoal-fired reactor, cocoa pod husks, maize cobs, maize stovers, slow pyrolysis.