OICC Press International Journal of Recycling of Organic Waste in Agriculture 2251-7715 14 2 2024 11 20 Effect of the combination tanks biochar and chicken manure on availability of nutrients and yields of Purple Eggplant 10.57647/ijrowa-vjsm-0w96 EN Urai Suci Yulies Vitri Indrawati Department of Soil Science, Faculty of Agriculture, Tanjungpura University, Indonesia https://orcid.org/0000-0001-8505-9914 Journal Article 2024 11 20 Purpose: Alluvial soil poses challenges for eggplant cultivation due to deficiencies in nutrients (N, P, K) and high Al/Fe content. This study aims to address these challenges by utilizing biochar from tank waste and chicken manure. Methods: Biochar materials, specifically from tanks and chicken manure, were pyrolyzed at 400°C for 4 hours. The resulting biochar was weighed to achieve the desired proportion and sieved through a 60-mesh sieve. It underwent analysis for pH, organic C, total-N, total-P, total-K, and Scanning Electron Microscopy (SEM). The tank's biochar was enriched with chicken manure biochar and NPK compound fertilizer at 75% of the recommended dose. The research involved two main components: 1) Planting purple eggplant seeds in polybags with varying treatments based on dosage, and 2) Chemical characterization of biochar, assessing soil N, P, K availability, and eggplant production up to the second harvest. Results: The combination of tanks biochar and chicken manure significantly increased soil N, P, and K availability: N by 73.68%, P by 35.36%, and K by 92.78% compared to the control. Harvest 1 yielded 90% of production, while Harvest 2 reached 16.50% compared to the control. Conclusion: Palm oil waste in the form of tanks biochar, enriched with chicken manure biochar and NPK compound fertilizer at 75% of the recommendation, has the potential to enhance alluvial soil fertility and promote growth and yield in purple eggplant plants. Research Highlights: Increased Nutrient Availability: The use of a combination of biochar and chicken manure increased the availability of nutrients N, P, and K in Alluvial soil Harvest Production: The results showed a significant increase in the yield of purple eggplant. Soil Quality: Application of biochar and chicken manure increased soil pH and organic content. Potential Use: This combination has great potential for use as an effective organic fertilizer in agriculture. Palm oil waste in the form of biochar tanks has special properties such as a porous structure with a sturdy shape. If enriched with biochar chicken manure and NPK fertilizer at a dose of 75% of the recommendation, it has the potential as an ameliorant to increase alluvial soil fertility as well as the growth and yield of purple eggplant plants.