Mandarin peels that used to be discarded after juicing have been reborn as eco-friendly farm inputs that reduce odors and attract pests.
The Rural Development Administration said on the 6th that it developed a resource-circulation technology that can recycle mandarin byproducts into eco-friendly farm inputs.
In Korea, about 40,000 tons (t) of byproducts—roughly 10% of annual mandarin production—are generated each year. Most have been discarded or simply recycled as feed by some livestock farms.
First, the Rural Development Administration sterilized and neutralized leachate extracted from mandarin byproducts and then cultured beneficial microorganisms (lactic acid bacteria, Bacillus subtilis, yeast, etc.) to produce an odor reducer. When this reducer was added to pig manure storage tanks, ammonia, a key odor component, fell 91% and hydrogen sulfide dropped 99%. Applying this in the field, the Rural Development Administration said a pig farm with about 2,000 head saw an annual income increase of 37 million won due to lower manure treatment expenses, among other effects.
The pest attractant used the "limonene" component generated during the mandarin juicing process. Limonene attracts female Protaetia brevitarsis and is known to be effective in reducing pest damage to sweet potato, ginseng, and pear farms. The Rural Development Administration explained that extracting limonene from mandarin byproducts for use can cut expenses by about 70% compared with buying limonene on the market to make attractants.
The research team also produced a soil conditioner using mandarin peels and pulp as raw materials. The input allows adjustment of the nitrogen-to-carbon ratio and phosphorus and potassium content by crop, and when mixed into soil, it showed more than 50% higher water retention than conventional perlite or bark and eased plant water stress by about 90%.
Going forward, the Rural Development Administration plans to pursue revisions to related laws by verifying the safety and assessing the environmental performance of the inputs developed. It also plans to expand industrial uses for mandarin byproducts to achieve both lower waste disposal costs and higher farm income.
Kim Dae-hyeon, acting head of the National Institute of Horticultural and Herbal Science, said, "Technology that puts mandarin byproducts back to work as agricultural resources can be expected to deliver multifaceted benefits, including reducing odors, managing pests, and improving soil, while cutting disposal expenses," adding, "It will contribute to strengthening farm competitiveness and spreading eco-friendly agriculture."