PHYSICOCHEMICAL CHARACTERIZATION AND STABILITY OF BIOCHARS INTENDED TO BE APPLIED AS SOIL AMENDMENTS

Waste biomass (WB) represents renewable resource that can be used in solving complex energy/environment demands. Possible route of WB revalorization is its thermochemical conversion into the biochar, which has remarkable potential as sustainable tool in biomass waste disposal issue, climate change mitigation, and soil environment protection. In this paper, four types of biochar were obtained by WB pyrolysis with intention to be applied as soil amendments. For that purpose, biochar samples were characterized according to Test Category A: Basic Utility Properties requirements according to the International Biochar Initiative (IBI). Analyses included basic properties required to assess the utility of biochar material for use in soil, such as physical properties of particle size and moisture, as well as the chemical properties of elemental proportions obtained from elemental organic analysis (EOA), ash proportion, electrical conductivity, pH and liming ability. Carbon stability was calculated from molar ratios of both H/C and O/C, as well as from proximate analysis results. EOA results shown that all investigated biochars have high content of carbon, ranging from 62.5 to 68.4, classifying them in Class 1 materials. Values of pH ranged between 7.68 and 8.99 indicating alkaline nature of biochars with potential for remediating acidic soils. Calculated H/C ratio was around 0.04 for all samples, while the O/C ranged between 0.40 and 0.54, indicating that biochars pose stable structure and high carbon sequestering potential. Electrical conductivity values showed benefits of biochars incorporation into the soil and valuable agronomic implications, offering beneficial soluble salts content.