Potential of Rice Husk Biochar and Bio-Oil with Varying Soaking Times as Environmentally Friendly Fertilisers to Increase Cayenne Pepper Productivity

Abstract

This research examines the potential of rice husk biochar activated by soaking in bio-oil for varying durations as an environmentally friendly organic fertiliser to support the growth of cayenne pepper plants. Proximate and ultimate analysis showed that rice husk contains carbon (33.89 wt.%), cellulose (33.80 wt.%), and lignin (19.84 wt.%), which support the formation of high-quality biochar. The biochar was characterised using XRF, identifying essential elements such as SiO2, K2O, P2O5, SO3, and MgO, which play a role in soil fertility. Plant growth observations on day 21 showed that soaking durations of 2 and 6 hours yielded the best results, with plant heights of 7.5 and 9.2 cm and leaf widths of 1.6 and 1.7 cm, respectively. Although the number of leaves did not differ significantly, it remained four across all treatments. XRF analysis of biochar-treated soil soaked for 6 hours showed a substantial increase in essential minerals compared to untreated soil, with increases ranging from over 38% to over 100% for elements such as SiO2, K2O, P2O5, Cl, SO3, and MgO. This increase in mineral elements contributes to improved soil structure, enhanced nutrient absorption, and better vegetative growth in chilli peppers. Overall, the research indicates that rice husk biochar soaked in bio-oil for 2 to 6 hours is highly promising as an organic fertiliser based on agricultural waste, supporting sustainable agriculture by improving soil fertility, reducing dependence on chemical fertilisers, and increasing the productivity of horticultural crops such as chilli peppers.