Assessing the Efficacy of Citronella and Oregano Biochar for Soil Enhancement

Abstract:

Organic waste constitutes the majority of waste in Lebanon, over 52%. This study aims to valorize organic waste and turn it into an environmental benefit by investigating the use of citronella (CymbopogonWinterianus) and oregano (Origanium Syriacum) residues as biochar. These plants are known for their aromatic compounds and produce substantial waste during cultivation and processing. The biochar was produced through pyrolysis at 400°C in a muffle furnace under an atmosphere devoid of oxygen, for one hour. The efficiency of oregano and citronella biochars as soil amendments (1% of soil mass 100 g) was evaluated by studying oregano plant germination and soil analysis and as adsorbant for methylene blue. Oregano biochar demonstrated the best performance, with significant improvements in plant heightof 24 cm, leaf dimensions 1.5 cm width and 1.7 cm length, chlorophyll concentrations 62.22% chlorophyll b and 37.36% chlorophyll a, and soil nutrient levels. Citronella biochar effectively removed 88.8% of methylene blue dye.After cultivation, the results show that the amendment of biochar offers an appropriate alternative strategy to achieve higher essential oil yield (higher in 30% than the other groups) in oregano plants without compromising the aroma quality of the soil. This study highlights the potential of using agricultural residues to create biochar and add it strategically as a fertilizer which has the concomitant advantage of enriching soil fertility for long-term sustainable agriculture with potential to reduce chemical fertilizer imputs, contributing to a circular bioeconomy and offering regional economic benefits.