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FROM FISH TO FERTILIZER
Centuries before contemporary scientific soil research began, cultures across the globe have understood the value of fish as fertilizer. In our efforts to restore and rehabilitate the loko iʻa of Waiāhole, Kapalaho & Kiʻonakapahu, we ideated ways to turn our challenges into opportunities by making fish emulsions out of the invasive Mexican mollies that inhabit our loko iʻa in great numbers.
KS' Ka Pili ʻOihana intern, Paele Kiakona—a senior at UH Hilo and 2013 KS Hawaiʻi graduate—in collaboration with haumāna from various K-12 schools, the University of Hawaiʻi at Hilo Analytical Laboratory and our Kumuola marine scientist-educators, led the charge to research and develop an inexpensive and easy-to-make fish fertilizer prototype that could be used in our māla to advance a healthy and sustainable loko iʻa ecosystem.
The Experiment
In this experiment, Paele co-created two emulsion mixtures using a Mexican molly and kō (sugarcane) recipe of different proportions—1:1 molly:kō and 1:7 molly:kō.
Both mixtures had been digested with an off-the-shelf probiotic over a three week period. The resultant emulsion was then strained and evaluated against a store-bought emulsion and sent to the UH-Hilo Analytical Laboratory for comparative testing.
The Results
While both Mexican molly emulsions were lower in initial nutrient concentration as compared to the store-bought emulsion, the tests did indicate beneficial concentrations of bioavailable nitrogen (N) and phosphate (PO4)!
Based upon these results, we can infer that both emulsions can be diluted to the same beneficial concentration as the store-bought mix and used as fertilizer.
This valuable data has enabled us to create other variations of fish emulsion prototypes as well as spur further research to look specifically at different molly:kō ratios, probiotic strains, digestion procedures, macro- and micro-nutrient concentrations, and a cost analysis on the products.
What Now?
The only way to find out if our fish emulsions really work is to test it!
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