Tsuchi-koji & Sumi-koji - Japan - ARI
by the Asian Rural Institute
page developed by Yu Araya, ARI Volunteer
submitted July 2021
Tsuchi-koji
for building healthy soil
https://gyazo.com/1a1d99a557c7138013f0f7572dc3b004
We can see white mycelia on this Tsuchi-koji pile. It means we made it successfully!
Have you ever had problems with crop pathogens? Conditioning the soil using Tsuchi-koji may help solve the problem!
Good and bad microorganisms
Microorganisms can be roughly divided into categories of good and bad. Bad microbes, such as fungal parasites and pathogens, living on plants and animals cause disease. On the other hand, good microbes, such as certain kinds of mold, yeast, and actinomycetes, mainly eat animal droppings and plant remains. That means they are harmless and even helpful as decomposers. Diseases often occur when these two groups do not exist in good balance. If we increase the number of good microbes, they can suppress the propagation of harmful microorganisms.
https://gyazo.com/cc865a9df5824309a9fbb94e71edcd22
Soil is healthy when there is a balance of 'good' and 'bad' microorganisms!!
What is Tsuchi-koji?
Tsuchi means soil in Japanese and koji means Aspergillus, which is a kind of mold often used for processing food in Japan. Tsuchi-koji is named after Koji, because it has a sweet and sour smell, which is similar to Koji. Tsuchi-koji is a kind of biological soil conditioner containing an abundance of good microbes such as Koji bacteria, Bacillus Natto, Lactic acid bacteria, yeast, and actinomycetes. There are several functions for Tsuchi-koji;
Maintains a balance of microorganisms to avoid continuous cropping disturbance. Continuous cropping disturbance refers the diseases that can occur when you grow the same kinds of crops continuously in the same place.
Actinomyces prevent diseases by producing antibiotics.
Promotes decomposition of organic matter such as plant residue.
Changes insoluble minerals into soluble minerals, which can be absorbed by plants.
The clay soil in Tsuchi-koji has a high Cation Exchange Capacity (CEC), which means it is easier for plants to absorb nutrients, and provides a living space for microbes.
How to make Tsuchi-Koji
Materials to prepare
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Clay soil and rice bran (in the paper bag) for making Tsuchi-Koji
Clay soil (250kg) - Clay soil should be collected from deep under the surface of the ground. this allows you to get clay soil which is free from disease, without nutrients, and not mixed with other kinds of soil.
Rice bran (20kg)
Water
Procedure
Put the clay, rice bran, and IMO3 together on the ground.
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Sprinkle the IMO3 between the soil and the rice bran.
Mix these ingredients while adding water. The moisture rate should be about 60%. If it makes a clump, but does not drip water, when you grab the mixture in your hand, it means the percentage is appropriate.
https://gyazo.com/d20277cdb8b6b8bc5d6210055de3e34f
Be sure the water is distributed through the whole pile!
Pile up the mixture and cover it with blankets or other breathable coverings to provide shade and keep it warm. Do not cover with plastic.
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Big blankets cover the pile.
Turn it over when the temperature reaches 45~55℃. We usually turn it once a day.
After 1~2 weeks, the temperature will go down, which means decomposition has finished. Spread the pile to let it cool and dry.
It is ready to be used or stored!
How to use
There are two main purposes for applying Tsuchi-koji to the soil, one is decomposing organic matter (such as the roots of previously cultivated plants) and the other is to increase the number of good microorganisms. You can broadcast on farmland with a concentration of 200kg~400kg/10a to the whole area of the field, 3~4 weeks before the sowing. If you apply right before sowing, the decomposition of organic matter will not finish and useful microbes will not increase by the sowing time.
Sumi-koji
There is another type of biological soil conditioner, which is called Sumi-koji. Sumi means charcoal in Japanese, so we know that this mixture contains charcoal. It is more effective compared to Tsuchi-koji because charcoal has several good effects on soil. (Click here to learn more about charcoal.) However, Sumi-koji is difficult to store for a long time so you need use it soon after making it. To make Sumi-koji, you can follow the recipe of Tsuchi-koji, but don't forget to add 11kg of charcoal before you mix all the ingredients with water. If you use rice husk charcoal, 11kg is equal to 2 containers.
You can apply Sumi-koji in the same way as Tsuchi-koji.
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