Cucumber waste from the greenhouse is a nutrient and high cellulose-rich biomass that could potentially be used to produce biochar as a valuable resource. Therefore, this study was conducted to produce biochar from cucumber green waste collected from a greenhouse in Qatar. The green waste was cut into small pieces (5 to 10 cm) for oven drying at a temperature of 105 °C for 24 h to remove moisture and was then pyrolysed in a muffle furnace at three temperatures of 300, 350, and 550 °C with a heating rate of 5 °C min-1 and residence time of 30 min. This study focuses on the nutrient analysis of biochar, including yield, pH and electrical conductivity (EC). Additionally, a small-scale pot test with cucumber plants applied 0% (control) and 2% biochar to a coco-peat substrate under a controlled microclimate with an enriched CO2 environment of 1000 ppm in a climate chamber. The pots were irrigated with a nutrient rich solution. Results demonstrate that the biochar produced with a higher pyrolysis temperature has a higher C content of 71%, pH of 10.59 and EC of 12.93 mS cm-1 with more aluminium, copper, and manganese. The lower pyrolysis temperature biochar possessed a higher N content of 3% and improved biochar yield of 48% with maximum potassium and iron concentrations. The application of 2% biochar was found to be linked to a maximum increase of 39% in plant height, 32% in leaf area, 3% in chlorophyll content, and a reduction of 71% in water loss by drainage as compared to the control. Moreover, both low and high temperature biochar applications display good plant growth by reducing water loss, while nutrient loss was more significant in the 2% biochar application at all three temperature conditions than the control. This study demonstrates that a lower fraction of biochar application could be beneficial for sustainable agricultural practices to reduce water drainage and nutrient supply.
Keywords: Cucumber; Green waste; Biochar; Plant growth; Water loss; Nutrients lea