Asian Journal of Plant and Soil Sciences

The processing of the fishery industry produces waste in the form of unused or wasted fish parts. The waste is estimated to be around 30–40% of the total weight of fish, molluscs and crustaceans. The fishing industry’s fishing waste reaches 20 million tonnes (20% of total production). Based on research, fish innards contain the elements N, P, and K, which the soil needs to fertilize plants. This study aimed to determine or understand the effect of differences in the length of fermentation time on the nutrient content of liquid organic fertilizer and tilapia viscera, which can be used as liquid organic fertilizer. This research was conducted in June – November 2022. Liquid organic fertilizer was made at the Fisheries Product Technology Processing Laboratory, Diponegoro University, Semarang. This research method used 500 grams of fish innards, 30 mL of EM4 concentration, and 50 mL of molasses. Research on the manufacture of liquid organic fertilizer carried out four types of treatment, namely, differences in the length of fermentation time. The results showed that the different fermentation times affected the characteristics of liquid fertilizer. The 15-day fermentation treatment produced the best results for tilapia viscera liquid organic fertilizer. 7.93% C-organic content, 0.67% N-total, 0.29% Phosphorus, 0.33% Potassium, pH 4.03, and 11.89 C/N ratio.