Tofu wastewater is a by-product of tofu production, with a volume reaching up to ten times that of the processed soybeans. This waste contains organic compounds such as proteins, carbohydrates, and fats, as well as essential minerals like nitrogen, phosphorus, and potassium, which can benefit plant growth but pose environmental risks if left untreated. One potential solution is to ferment the wastewater using the EM4 bioactivator and coconut water, which is rich in growth hormones and minerals. This fermentation process produces a nutrient-rich and eco-friendly liquid organic fertilizer (LOF), which can serve as an alternative to chemical fertilizers that are often misused by farmers.

This study aims to evaluate the potential use of fermented tofu wastewater and coconut water as a liquid organic fertilizer for the growth of land spinach (Ipomoea reptans). Land spinach was selected due to its high consumption rate and ease of cultivation.

Based on the results, it can be concluded that the application of fermented tofu wastewater and coconut water enriched with EM4 has a significant effect on several growth parameters of land spinach, including stem diameter, fresh weight, number of nodes, leaf area, plant height (at 21 and 28 days after planting), and number of leaves (at 14, 21, and 28 days). The best growth results in this study were observed in treatment F6 (40% tofu wastewater fermentation), although the outcome did not surpass that of the positive control. These findings indicate that fermented tofu wastewater and coconut water have the potential to serve as an alternative liquid organic fertilizer that promotes sustainable agriculture while also reducing tofu industry waste.

Keywords: tofu wastewater, liquid organic fertilizer, fermentation, water spinach.