Agro-environmental characterization of biochar issued from crop wastes in the humid forest zone of Cameroon

Samuel Fru Billa,Ajebesone Francis Ngome,Tsi Evaristus Angwafo

doi:10.1007/s40093-018-0223-9

Abstract

PurposeCrop wastes are underused organic resources due to low heating value and slow decomposition rates. However, conversion to biochar through pyrolysis could offer agronomic and environmental benefits. The study compared the pyrolysis of biochar from crop wastes, assessed their physicochemical properties for the purposeful use to improve soil fertility, crop productivity and their carbon sequestration potential.MethodsBiochar was produced from crop wastes such as cassava residues, corncobs, rice husk, sawdust, coffee husk, and peanut using an Elsa barrel pyrolyser. Standard laboratory procedures were used to analyze pH, CEC, total carbon and nitrogen and exchangeable cations.ResultsThe biochars were high in nutrients containing 4.17–18.15 g kg−1 N, 22.26–42.51 mg kg−1 P, 2.48–4.18 cmol kg−1 K and pH 7.78–10.81 units. It is evident that adding biochar to acidic soil containing 0.79 g kg−1 N, 7.41 mg kg−1 P, 1.42 cmol kg−1 K and pH of 5.68 could increase soil fertility and plant productivity. Carbon dioxide reduction potential ranged from 94.46 to 313.42 CO2 eq kg−1. This implies that the concept and technique of producing biochar could be a valuable way of reducing carbon emissions into the atmosphere thereby mitigating climate change.ConclusionCrop wastes and by-products which constitute a nuisance could be used to produce a very useful by-product, biochar whose quality depends on the substrate from which it is produced. Recycling crop wastes to biochar is strongly recommended to smallholder farmers for use in agriculture to improve fertility and crop productivity due to their high nutrient content and soil fertility attributes.

Highlights

A large percentage of organic resources produced globally are inefficiently used and not recycled (Rajaie and Tavakoly 2016)
The result from the biochar production study showed that many types of crop wastes can be effectively converted to biochar using the Elsa barrel compared to other methods such as the Japan retort method (Fig. 1d) where only rice husk could be carbonized
The short carbonization time for rice husk, coffee and groundnut husk could be due to the small quantity, dry, brittle nature and less dense material which burn much easier and faster as compared to the densely packed and woody biomass corncob and cassava which required high temperature and longer carbonization time (Joseph et al 2013; Domingues et al 2017)

Summary

Introduction

A large percentage of organic resources produced globally are inefficiently used and not recycled (Rajaie and Tavakoly 2016). Biochar is a carbon-rich material produced by pyrolysis (thermochemical conversion) of organic materials such as agricultural residues of plant and animal origin, forestry and wastes from food-related industries in a controlled low-oxygen environment (Steiner et al 2010; Sohi et al 2010; Shackley et al 2011). This process known as pyrolysis has recently attracted attention as a means to add value to organic wastes for agricultural use (Rafiq et al 2016).

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Conclusion