Effects of Fish-derived Liquid Fertilizer on Growth of Wolffia globosa during the Monsoon Season

Wolffia globosa has been considered a functional food formulation due to its excellent nutritional value and rapid growth. Organic liquid fertilizer from fish (OLF) has been used as a source of nutrients for plant growth. However, there is limited information regarding the use of OLF for the cultivation of W. globosa. This research aimed to cultivate W. globosa using OLF during the monsoon season.

Two outdoor experiments were conducted during the monsoon of 2025. Experiment 1 comprised eight treatments of OLF, being 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 mL/L. The plant was grown on rainwater in 11-L plastic containers covered with 50% black shade cloth and harvested at 11 days. Experiment 2 resembled the cultivation system in small-scale farms and comprised three treatments: 1.5, 2.5, and 3.5 mL/L, with OLF added during the experiment. OLF was made from fish waste collected from a local supermarket. The plant was grown on tap water in open 1.2-m diameter cement ponds. Biomass (g) was monitored every five days for 30 days. Daily rainfall was collected during the two experiments.

Biomass gain was lower in Experiment 1 (1.8-2.4 times the starting mass) than in Experiment 2 (2.6-4.1 times the starting mass). Biomass was greater at higher rates of OLF in both experiments, although differences were not always statistically significant;biomass per unit area (g/m²), average daily biomass gain (g/day), and daily productivity (g/m²/day) were greater at higher rates in Experiment 2. Biomass per unit area exceeded 2 kg/m² in treatment 3.5 mL/L after 30 days. In the three treatments, average daily biomass gain was the highest at 15 days (48.85-66.76 g/day), while daily productivity was the highest at five days (89.08-105.77 g/m²/day).

OLF as high as 3.5 mL/L could fertilize W. globosa under the conditions of this study.

It is practical to cultivate W. globosa using OLF without changing media for a 30-day period. However, farmers may harvest the plant at 15 days, as average daily biomass gain reached a peak, and then restart the whole process of cultivation with the new media.