The first step to organic hydroponics – preparing microbial culture solutions with easily accessed household liquid organic fertilizers in a subtropical farm

Hydroponics is not the end of organics.
Organic hydroponics can be realized by directly adding biological fertilizers derived largely from animals and plants.
It is exemplified by Shinohara (2006) using a fish-based soluble fertilizer to culture microbial nutrient solution for organic hydroponics.
Although this method makes redirecting organic liquid wastes into the food cycle through hydroponic possible, its success relies on the mineralization of organic compounds into inorganic nutrients by the microorganism in hydroponic solutions.
The mineralization is subjected to cultural conditions.
However, little research explored the applicability of the method in another climate zone.
Thus, this study aimed to shorten and simplify the preparation process and track the mineralization in subtropical climate zone.
We adapted the method and conducted a field test focusing on the preparation of nutrient solutions using fermented organic fertilizers based on expired soya milk and cow milk during summer and autumn in southern Taiwan.
Along the process, we recorded the changes in cultivating conditions including solution temperature and the concentration of nitrate ions.
Leafy lettuce seedlings were transplanted into the system to verify the nutrient solution’s maturity.
The results show that the concentration of nitrogen increased gradually in four months.
In the first month with no seedlings, the concentration of nitrate reached 43 mg L^‑1. In the second month when seedlings were transplanted, it reached 99 mg L^‑1. In the final two months with seedlings, it reached 167 mg L^‑1. Despite the changes in fertilizer types and culture conditions, mineralization took place at a rate similar to previous research and along the process.
Although additional microbial inoculum has been purposely placed in the system, seedling roots served the same function additionally.

IV Asian Horticultural Congress – AHC2023

T.I. Lee, Y.H. Hsieh, Y.Y. Hsieh, H.Y. Chang

bioponics, microbial nitrification, phytotoxicity, organic hydroponic solution, seedling establishment

https://doi.org/10.17660/ActaHortic.2024.1404.29