Use of Shallot Peel Waste and Cassava Active Powder (AHL) in Improving Available Phosphorus and Potassium on Vertisol and Yield of Tomato <i>(Lycopersicum esculentum</i> Mill)

Abstract Vertisol soils are typically characterized by low phosphorus and potassium availability, largely due to their high clay content in topsoil. This study investigates the potential of enhancing phosphorous and potassium availability through the application of organic matter, specifically liquid organic fertilizer derived from shallot skin and cassava active-powder (AHL) as a promoter of soil microbial activity. The experiment was arranged in a completely randomized design with three replications. The treatments included different combinations of shallot skin liquid organic fertilizer and AHL B0A0: no shallot skin liquid fertilizer + no AHL, B0A1: no shallot skin liquid fertilizer + 0.01 g/2 mL AHL, B0A2: no shallot skin liquid fertilizer + 0.02 g/2 mL AHL, B1A0: 25% shallot skin liquid fertilizer + no AHL, B1A1: 25% shallot skin liquid fertilizer + 0.01 g/2 mL AHL, B1A2: 25% shallot skin liquid fertilizer + 0.02 g/2 ml AHL, B2A0 50% shallot skin liquid fertilizer + no AHL, B2A1: 50% shallot skin liquid fertilizer + 0.01 g/2 mL AHL, B2A2 : 50% shallot skin liquid fertilizer + 0.02 g/2 mL AHL, B3A0: 70% shallot skin liquid fertilizer + no AHL, B3A1: 70% shallot skin liquid fertilizer + 0.01 g/2 mL AHL, B3A2: 70% shallot skin liquid fertilizer + 0.02 g/2 mL AHL). The observed parameters included available phosphorus, available potassium, total soil microorganism, fresh weight, and the number of fruits per plant. Data were analysed using Analysis of Variance (ANOVA) followed by Duncan’s Multiple Range Test at a 5% significance level. Result showed that combined application of liquid organic fertilizer from shallot skin and AHL significantly influenced all parameters. The treatment of B3A2 (70% shallot skin liquid fertilizer + 0.02 g/2 mL AHL produced highest effects, with total soil microorganisms count reaching 123 CFU/g, available phosphorus at 102.13 ppm, available potassium at 0.37 me/100g, fresh tomato weight at 323.46 g/plant, and 16 fruit per plant.