Korean Natural Farming for home gardens

Korean Natural Farming (KNF) is a biological farming system developed by Cho Han Kyu in South Korea in the 1960s--70s and formalized at the Janong Natural Farming Institute. It emphasizes using locally sourced fermented materials -- primarily indigenous microorganisms, plant-based inputs, and.

—- title: "Korean Natural Farming for home gardens" slug: korean-natural-farming-basics hub: care category: "Advanced technique" description: "An evidence-based guide to Korean Natural Farming (KNF) for home gardens, explaining the core inputs, what the research supports, and where claims outrun evidence." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 9 —-

Korean Natural Farming (KNF) is a biological farming system developed by Cho Han Kyu in South Korea in the 1960s—70s and formalized at the Janong Natural Farming Institute. It emphasizes using locally sourced fermented materials — primarily indigenous microorganisms, plant-based inputs, and fermented fruit and mineral preparations — to enhance soil biology and plant nutrition. Per University of Hawaii Cooperative Extension, which has produced the most extensive English-language peer-reviewed research on KNF in the US, the system has measurable agronomic effects in some contexts, though the mechanisms and optimal applications are still being characterized.

The core inputs

Per University of Hawaii CTAHR Extension, the primary KNF inputs are:

1. Indigenous Microorganism inoculant (IMO)

What it is: A microorganism concentrate collected from the local environment (typically woodland soil or decomposing leaf litter) and multiplied on a cooked grain substrate (typically rice), then preserved with sugar.

How it's made:

1. Place cooked rice in a wood or bamboo box (not metal)
2. Cover with breathable cloth; place in a forest floor location in direct contact with leaf litter for 5—7 days
3. White fluffy mycelium (fungal growth) colonizes the rice — this is IMO-1
4. Mix IMO-1 with brown sugar (1:1 by weight) to preserve it — this is IMO-2
5. Mix IMO-2 with bran and soil to produce IMO-3 and IMO-4, progressively increasing volume

What research shows: Per University of Hawaii CTAHR research published in HortScience, IMO applications increased soil microbial biomass carbon and soil enzyme activity in field trials. Effects on plant yield were positive but variable.

Caution: The specific fungal and bacterial strains collected vary by location, season, and substrate. The system is inherently variable; results in Hawaii (tropical) may not translate directly to zone 6 garden soils.

2. Fermented Plant Juice (FPJ)

What it is: A fermentation extract made from plant material (typically fast-growing young shoots — licorice, comfrey, bamboo, or other vigorous plants) mixed with brown sugar at a 1:1 ratio and fermented for 1 week.

How it's made:

1. Collect fresh plant material in early morning (highest sugar content)
2. Chop finely; pack tightly in a container; add brown sugar at 1:1 by weight
3. Cover with breathable cloth; ferment at room temperature for 5—7 days
4. Strain liquid; store in glass container; use at 1:1000 dilution as a foliar or soil drench

What research shows: Per CTAHR Extension, FPJ from certain plants provides plant hormones (cytokinins, auxins) that influence plant growth at appropriate dilutions. The specific hormone content depends entirely on the source plant.

3. Fermented Fruit Juice (FFJ)

Similar to FPJ but made from ripe fruit to provide sugars and fruit hormones. Used during fruiting and ripening. Per CTAHR Extension, used at 1:500—1:1000 dilution during fruit development phase.

4. Water Soluble Calcium (WCA / OHN-Ca)

What it is: Calcium extracted from eggshells or crab/shrimp shells by soaking in vinegar, producing calcium acetate.

How it's made:

1. Bake eggshells at 300°F for 20 minutes (calcination)
2. Soak in apple cider vinegar (1:10 shells to vinegar) until bubbling stops (calcium dissolves as calcium acetate)
3. Strain; use at 1:1000 dilution as foliar spray for calcium uptake

What research shows: Per NC State Extension, foliar calcium applications are most effective at fruit set and when soil calcium is deficient. The KNF calcium acetate form is more mobile in plant tissues than calcium chloride, per some preliminary research.

5. Oriental Herbal Nutrient (OHN)

A fermented herbal extract using garlic, ginger, cinnamon, and other herbs in alcohol or brown sugar. Per CTAHR Extension, OHN is used as a plant health tonic and has some antimicrobial properties attributable to plant secondary metabolites. The evidence for specific disease control effects is limited.

6. Lactic Acid Bacteria (LAB)

What it is: A lactic acid bacteria culture derived from rice wash water fermented with milk.

How it's made:

1. Wash rice in water; save the wash water; let ferment for 5 days at room temperature
2. Mix 1 part rice wash ferment with 10 parts whole milk; ferment for 5—7 days
3. The clear liquid separates from the curds; collect the liquid (LAB serum)
4. Mix with molasses for storage; use at 1:500—1:1000 dilution

What research shows: Per CTAHR Extension, LAB applications have shown measurable effects on soil microbial diversity in some trials. Lactic acid bacteria are well-documented in fermentation science; their soil effects are less well characterized.

Application schedule

Per CTAHR Extension, a typical KNF application schedule:

What the evidence supports vs. what it doesn't

Per University of Hawaii CTAHR Extension series (SA-7 through SA-14):

Supported:

• IMO applications increase soil microbial biomass carbon
• FPJ from appropriate plant sources provides plant hormones at low dilutions
• KNF-managed systems can reduce synthetic fertilizer and pesticide inputs
• LAB improves some soil microbiome diversity metrics

Not well-supported or mixed evidence:

• KNF pest repellency claims (OHN as insect repellent) — limited controlled trial data
• Yield equivalence to conventional production in all crops — mixed; some crops show yield reduction in KNF systems vs. conventional
• Universal transferability across climates — most research is tropical/subtropical; temperate zone data is limited

Practical starting point for home gardeners

Per CTAHR Extension, the two most accessible and best-supported KNF inputs for beginners are:

1. IMO-3 or IMO-4 applied to garden beds at 1—2 lbs per 100 sq ft, tilled lightly into the surface — a direct microbial inoculant with documented soil health effects

1. FPJ from comfrey or nettles at 1:1000 dilution as a foliar spray during vegetative growth — provides trace plant hormones with low risk and low cost

These two represent the most consistent research base. The more elaborate multi-input schedules are beneficial for those invested in the full system but beyond the evidence-base for a simple recommendation to home gardeners.

Common problems

Frequently asked questions

Is Korean Natural Farming the same as biodynamic farming? No. Both are alternative approaches emphasizing biological inputs and farm organism health, but they have different philosophical and practical bases. Per CTAHR Extension, KNF is based on microbial ecology and fermented inputs; biodynamic farming (Steiner, 1920s) incorporates astrological timing and specific preparations. They are separate systems.

Is KNF research peer-reviewed? Per University of Hawaii CTAHR, the CTAHR KNF series represents the most rigorous peer-reviewed English-language research. Some findings are published in HortScience and Agronomy Journal. Much practitioner knowledge in KNF is experiential rather than formally published.

How does KNF compare to simply using compost? Per Penn State Extension, good compost provides a broad microbial inoculant, organic matter, and slow-release nutrients in one input. KNF inputs provide more targeted microbial and hormonal effects but require significantly more time to prepare. For most home gardeners, excellent compost is more accessible and arguably more broadly effective than the full KNF input schedule.

Is there a risk from the homemade preparations? The main food-safety concern with fermented inputs is ensuring fermentation (lactic acid/sugar preservation) rather than putrefaction. Per CTAHR Extension, the sugar-based preservation method is safe when done correctly; LAB serum is produced similarly to traditional fermented foods.

Sources

1. University of Hawaii CTAHR Extension — Korean Natural Farming series (SA-7)
2. NC State Extension — Foliar calcium
3. Penn State Extension — Soil health management
4. USDA NRCS — Soil biology