Fermented Plant Juice (FPJ) - Japan - ARI
by the Asian Rural Institute
page developed by Rina Tanaka, ARI Volunteer
submitted December 2020
Fermented Plant Juice (FPJ)
to promote the healthy growth of plants
The only ingredients you need for FPJ are plants and sugar!
What is Fermented Plant Juice and why do we use it?
Fermented Plant Juice (FPJ) is called Ten Kei Ryoku Ju (天恵緑汁) in Japanese. “Ten” means sky, heaven, or nature; “Kei” means blessing; “Ryoku” means green; and “Ju” means juice. Therefore, Ten Kei Ryoku Ju means Green Juice that is a gift from Nature. As the name implies, FPJ can bring many benefits to our farms when used appropriately.
The main ingredient of FPJ is green plants. We extract the juice of these plants by mixing them with crude sugar. The sugar also serves as food for beneficial microorganisms living on the plant leaves, and these microorganisms ferment the extracted plant juice. The resulting fermented plant juice is rich in plant nutrients, beneficial microorganisms, enzymes, growth hormones, natural insect repellants, and disease preventers. All of these things promote healthy plant growth.
You can also use fruits or fish protein as the main ingredient to make Fermented Fruit Juice (FFJ) and Fish Amino Acid (FAA), respectively.
How do we make FPJ?
1. Preparing the plant materials for FPJ
FPJ can be made from ordinary materials that are found in your local environment. For example, you can use plant leaves, seedlings that are removed for thinning, grasses, seaweed, or weeds such as mugwort, dropwort, and clover. Selecting the appropriate materials is important since it determines the amount of nutrients and beneficial substances in FPJ. Below are some things to consider:
You should use plants or parts of the plants that grow fast because they contain more growth hormones. Some examples of fast-growing plant parts include bamboo shoots, young grasses, and the growth points (tips) of plants. Keep in mind that a leaf stores more nutrients than a stem.
It is a good idea to collect materials from the same plants that you plan to apply the FPJ to. For example, FPJ made from the pruned vines or young fruits of cucumbers are most effective when applied to cucumber plants. This is because FPJ made from the same plants it is used on is full of essential substances that that plant exactly needs.
Cutting the growth points (new leaves) of mugwort plants / Thinning soybean seedlings]
There are several considerations when collecting materials for FPJ.
Materials should be collected before sunrise because that is when plants have the maximum amount of nutrients. During the night, plants store the nutrients, and during the day, they use up the stored nutrients through photosynthesis. Therefore, dawn is the best time to pick the materials.
Materials should NOT be collected during or right after rain because microorganisms are washed away from the plants. After the rain, it will take about two days for the bacteria on the leaves to return to the previous level.
Materials should NOT be collected during dry periods because there will not be a lot of liquid in the plants, making it difficult to extract plant juice. If you have to make FPJ in the dry period, materials should be watered on the previous day.
After collecting the material, FPJ should be made as soon as possible because the nutrients and energy of the plants will decrease as time passes.
Plant materials collected in a bucket
2. Mixing the plants with crude sugar
Without washing the plants with water, mix the plant material thoroughly with crude sugar. The amount of sugar should be half or one third of the weight of the plants. The appropriate amount also changes by season. It should be a little more in the spring and a little less in the summer.
Plant leaves being mixed with crude sugar
There are two reasons for mixing the materials with crude sugar - extracting and fermenting the plant juice.
Extracting the plant juice through osmosis
The crude sugar pulls out the plant juice from the leaves through a process called osmosis. We use osmosis to extract plant juice instead of boiling the plants because heat will chemically alter the beneficial substances that are extracted. (For a more detailed explanation of osmosis see the footnote at the end of this page*).
Fermenting the plant juice
Another purpose for adding crude sugar is to provide food for microorganisms which ferment the plant juice. During the fermentation process, the microorganisms produce beneficial enzymes and break down complex organic matter into simpler forms so the plants can easily absorb them as nutrients. In addition, microorganisms such as lactic acid bacteria and yeast feed on sugar and produce alcohol. This alcohol can extract chlorophyll which is where the plants store their nutrients.
Is it okay to use other types of sugar instead of crude sugar?
The reason we recommend using crude sugar is because it is very sweet (which is favorable for fermentation) and contains minerals. However, it can be expensive, depending on where you live. In such a case, you can substitute it with other types of sugar, such as molasses, cane juice, jaggery, palm juice, palm sugar, and even sweet fruits like mango. Any of these sugars come with advantages and disadvantages. For example, molasses contains minerals and is cheaper than crude sugar, but has high water content which is not good for osmosis. Therefore, you should decide on which type of sugar to use considering its quality, cost, and availability.
Can we use salt instead of sugar to extract plant juice?
Yes and no. You cannot fully substitute sugar with salt. First, salt does not serve as food for the microorganisms. Second, too much salt can be harmful to plants. Since the microorganisms do not eat salt, the salt will remain in the FPJ, so when you apply the salty FPJ to your vegetables, water in their roots might be pulled out due to osmosis. However, if you have some difficulty extracting the plant juice using only sugar, you can add a little bit of natural salt to promote osmosis. The quantity of natural salt should be less than one third that of the crude sugar.
3. Putting the plant and sugar mixture in a container
For the container, ceramic pots, wooden boxes made of cedar, or bamboo pots are the best because they are resistant to temperature change. If there are no such pots, plastic pots are also okay, but metal containers should be avoided. Make sure there are no cracks in the container or else the extracted plant juice will leak out!
A ceramic container
4. Putting a weight on top of the plant mixture and covering the mouth of the container with paper and a string
Basically, we want to see two types of fermentation happening inside the container: (1) anaerobic (which does not use oxygen) at the bottom of the plant material and (2) aerobic (which uses oxygen) at the surface.
First, for anaerobic fermentation, we need to remove air from the bottom. We put a heavy object on top of the plant material inside the container. The weight of the object should be about half the weight of the plant material. A plastic bag filled with water works well because it can change its shape according to the shape of the container. You can also use stones. Then, cover the top with some cloth or paper to prevent insects and dust from getting in, and put the container in the shade.
Heavy objects used to remove air at the bottom of the container; a plastic bag filled with water / stones
Container covered with paper and tied with a string
5. After 1 or 2 days, remove the heavy object and replace the covering
Next, for aerobic fermentation, we remove the heavy objects. At this point, the plant material should fill two thirds of the pot. If the container is too full, aerobic fermentation will not occur smoothly due to poor air circulation. After removing the heavy object, cover the mouth of the pot again with a sheet of paper tied with a string. Store it in a cool dark place and wait for the fermentation to complete.
How do I know when fermentation is complete?
Typically, it takes 1-2 weeks to finish fermenting, depending on the climate; the hotter, the faster because the microorganisms will be more active. You can also look for signs that fermentation has ended by checking if the color has changed from green to yellow or brown and if the smell is sweet and alcoholic.
Waiting for the fermentation process to finish
6. After fermentation is complete, remove the plant residue
When the fermentation process is finished, discard the plant residue. DO NOT SQUEEZE the plants to get more juice! If you squeeze the residue, other undesirable things will come out and mix into the FPJ. The plant residue can be used for compost because it contains many microorganisms and enzymes.
Fermented plant juice / Plant residue
How do we preserve FPJ?
Although it is better to use FPJ as soon as possible for the best quality, it can be kept for up to five years if you put it in a container with the lid tightly closed and store it in a cool dark place.
FPJ preserved in a plastic bottle with a lid
How do we use FPJ?
There are many ways to use FPJ! One important thing to keep in mind when using FPJ is to dilute it to the right concentration. You might think the more concentrated the FPJ is, the more effective it is. This is NOT true. If the concentration of FPJ is too high, the plants will not be able to absorb the liquid fast enough. This can attract pests that will feed on the sugar in FPJ and harm the plants.
Applying diluted FPJ to soil
Applying to plant leaves (1:500)
FPJ can be applied to plant leaves to strengthen their vital energy. Before it is applied, it should be diluted 500-700 times with water. It is more effective to spray FPJ on the back side of the leaves because there are more pores there. Adjusting the concentration of FPJ to the stages of plant growth is also important. For example:
At the early stages of vegetative growth, FPJ of low concentration should be used so that the plants do not become dependent on applied nutrients
At the reproductive stage, it is okay to spray FPJ of high concentration.
In addition, when plants become damaged due to cold weather or typhoons, you can use FPJ. It will help restore the microorganisms on the surface of the leaves and cure the plants.
Applying to the soil (1:1000)
FPJ can be applied to fields to promote microbial activity and plant health. It supplies nutrients to microorganisms that live around the plant root hairs. In particular, after sowing or transplanting, you can water the soil with FPJ diluted 1000 times with water (low density). You can also apply FPJ to the soil when the roots of the plants become weak due to continuous dry days or too much fertilization.
Applying to seedlings before transplanting (1:1000)
At ARI, we mix a small amount of FPJ with water to soak the roots of vegetable seedlings that are waiting to be transplanted. This helps the seedlings maintain vitality.
Applying to Bokashi (1:500)
You can add FPJ to the water that is used to make Bokashi. This FPJ should be diluted 500 times with water.
Applying to animal bedding (1:1000)
FPJ can be applied to animal bedding to promote manure decomposition and reduce odor.
For weakened animals (1:500)
FPJ can be added to animal feed, diluted 500 times with water. This can increase helpful microorganisms in their guts.
*Notes on osmosis
To understand how you can extract plant juice from plants by mixing them with crude sugar, we have to understand osmosis.
When sugar is mixed with plants, the sugar concentration of liquid outside the plants becomes much higher than that of the inside the plants. Then, the juice inside the plants (mostly water, but also contains things like chlorophyll which are smaller than the pores on the plant surface) comes out to equalize the sugar concentrations of liquid on both sides. We call this phenomenon “osmosis.”
Osmosis. After mixing the plants with crude sugar, the sugar concentration of liquid outside the plants becomes much higher than that of inside the plants. Due to osmosis, water will move from inside to outside the plants through the pores on the plant surface to equalize the sugar concentrations of liquid on both sides of the plant surface. This is how we can extract plant juice.
Han-kyu, C. (1998). Ten kei ryoku ju no tsukurikata to tsukaikata (How to make and use fermented plant juice). Japan: Nobunkyo.
Tancho, A. (2013). Applied natural farming: Principles, concepts & appropriate techniques in tropics. Thailand: Trio Advertising & Media Co. Ltd.