Determination of Some Characteristic Properties of Biochar Obtained from Different Agricultural Wastes

Abstract

Recycling of post – harvest wastes, which do not have any input qualities, to biochar is of great importance. The use of biochar increases soil quality and crop yield. Biochars used in the study were produced from residues of the locally grown crops: corn cob (CC), cotton stalk (CS), tobacco stalk (TS), pistachio shells (PS), and olive pulp (pomace) (OP). The biochars were produced via the carbonization method at 300°C. Biochar materials were evaluated for their properties (pH, EC, total C, N, H/C ratio, C/N ratio) and mineral concentration (Ca, Na, Mg, K, Cu, Zn, Fe, Mn, B, Al, Ni, P, Pb) before and after biochar processes. Surface morphology properties were observed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The conversion of crop biomass into biochar resulted in weight losses of between 42% and 69%. The pH of all biochars was alkaline (pH> 7). PS biochar exhibited the highest electrical conductivity (EC: 4.54 dS m-1) compared to other biochar materials. Biochar total carbon levels ranged from 58.06% to 80.29%, with the highest carbon concentration found in biochar obtained from corn cobs. In terms of total nitrogen, biochar obtained from cotton straws had twice as much nitrogen compared to the other four biochars, resulting in the lowest C/N ratio. H/C ratio ranged between 0.04 and 0.09. The mineral concentration of the materials also increased following biochar conversion. SEM micrographs showed higher porosity in CSB, CCB, and TSB with well-structured pores, while in PSB and OMB, the pores were not well-developed. SEM-EDX analysis of mineral elements (e.g., K, Mg, Si, and P) showed significant results in the derived CCB. In conclusion, this study demonstrates the diverse properties and mineral concentration of biochars derived from various agricultural residues, highlighting their potential for sustainable soil improvement.