The Effect of Vermicompost and Liquid Organic Fertilizer (POC) Application on Soil Biological Properties, Growth, and Yield of Tomato (Solanum Lycopersicum L.)

Tomato (Solanum lycopersicum L.) is one of the most important horticultural commodities with high economic value. However, its productivity has significantly declined due to land degradation, particularly in marginal soils such as Ultisols, which are characterized by low organic matter content and nitrogen deficiency. Improving soil fertility and enhancing tomato yield can be achieved through the application of solid organic fertilizer in the form of vermicompost (kascing) and liquid organic fertilizer (POC). This study aimed to: (1) determine the optimal dose of vermicompost to improve soil biological properties, growth, and tomato yield; (2) identify the best POC concentration to enhance tomato productivity; and (3) evaluate the interaction between vermicompost and POC on soil biological properties, growth, and yield of tomato. The experiment was arranged in a factorial Randomized Block Design (RBD) with two factors: vermicompost doses (0 g, 20 g, 40 g, and 60 g/plant) and POC concentrations (0 ml/L, 30 ml/L, and 60 ml/L), each replicated three times. The results showed that vermicompost application had a highly significant effect (P < 0.01) on almost all parameters, including soil microbial population, plant height, number of leaves, number of flowers, number of fruits, fruit weight per plant, and yield per hectare. The application of 60 g/plant vermicompost produced optimal growth with the highest number of flowers (73.50), fruits (87.33), fruit weight per plant (1540.73 g), and yield (3.06 t/ha). Similarly, POC application had a highly significant effect on vegetative and generative growth, where a concentration of 60 ml/L accelerated flowering (38.83 days after transplanting) and increased the number of leaves and fruit weight. The interaction between vermicompost and POC also showed synergistic effects, with the best combination obtained at 60 g/plant vermicompost and 30 ml/L POC. These results demonstrate that the integrated use of vermicompost and POC is effective in improving soil biological properties and enhancing the growth and yield of tomato in a sustainable manner.