Adventures with Bokashi

Recently I discovered that while I was waiting for my compost heaps to be ready, local organic farmers always had a surplus of organic fertilizer. So much so, that they even sold it in bags.

I then discovered that what they were making was bokashi. Honestly I felt quite embarrassed for never having heard of it before. But once I put my pride aside and began to research it I realized why this was such a common fertilizer technique.

Bokashi is a Japanese term that means, fermented organic matter. In essence it is similar to compost with some major differences that sets it apart.

Firstly bokashi is made with very fine starter material such as bran (rice or any other) coffee hulls (the by product after removing the bean), chicken and/or horse manure. This material is very fine, and thus decomposes or ferments quickly.

To this certain mineral additives may be added such as wood ash, bone meal and or rock phosphate, and/or ground limestone.

The most important ingredient however is good soil. Bokashi generally uses a large percentage of soil, typically 25% of the total mass. The best type of soil to use is dark forest soil. This acts as an inocculant of good microbes that aid in the fermentation product.

The ingredients are mixed thoroughly and moistened. The moisture content is very important. when the mixture is squeezed in the hand it should clump together lightly but not drip. If it soggy, heavy, or dripping it is too wet. If it doesn't clump at all it is too dry.

the mixture is kept dry but well aerated. So it must be under a roof or lightly cover with plastic. It can be kept on a bare floor or concrete for easy turning. The temperature of the bokashi will raise rapidly, and so it must be turned and aerated at least twice a day for the first week. Also the bokashi pile should not be higher that 50cm.

In the first week the bokashi heats up tremendously, this is ok as long as it doesn't get too hot. It should not get as hot as the compost pile. So 40 degrees Celsius max.

The life of the bokashi is such:

The first day it heats up tremendously
within the first week it stays hot and begins to smell of fermentation (a very distinct odour)
Next it begins to cool but maintains the odour.
Once the pile begins to cool, it is dried, until the odour disappears.

What you are left with is a rich, lush compost like material full of beneficial organisms ready to aid in the assimilation of nutrients from the soil for the plants.

The magic compost Mix

Compost is vital for nutrient depleted soil, however in the tropics, nutrients tend to leach out dramaticaly and the addition of any kind of fertilizer is highly inefficient.

Therefore charcoal aka pyrogenic carbon, biochar is vital in tropical soil systems.

Charcoal can be added directly to soil or into the compost heap itself. First we beat the charcoal to get it to small particles of no more than 1cm in diameter, then we mix about three sacks or more into into the compost pile. The compost pile also consist of vegetation, kitchen scraps and animal manure. We also add two layers of calcium and two layers of phosphorus rock dust. This mixture is mixed well with added water to get the optimal moisture for decomposition and placed in a one meter by one meter wide compost pile maintained by sticks (picture coming soon)and piled about 1.5 m high. The compost is checked for temperature and moisture periodicaly and and only mixed and re-moistened if deemed necessary.

Temperature is important and I like to make sure it gets very hot especialy when using manure (from our farm). By monitoring the temperature I can determine what stage the compost is in. I monitor it by inserting a machete into the heap and leaving it there for a while. Once I remove it I consider it hot (thermophile stage)when it is so hot that I have to remove my hand quickly, and I consider it warm (active stage) when the machete doesn't feel burning hot but comfortably warm to the touch.

Idealy when the heap cools down it is inocculated with beneficial bacteria (more on that later) and worms. Finding worms in my area has been a challenge so that is something I have been able to do yet.

Here I post a picture I took a few days ago when I sent my soil to be tested. I have two samples, one is virgin soil from our farm that has not been manipulated, and the other is treated soil (two years old), with carbon and organic fertilizer. It has only been fertilized twice in the last two years.