Sunday, March 28, 2010

Rice Hull Charcoal- Making and Using it

(Rice hulls before charring)

Ok, so now you are wondering what rice hull charcoal can do for you? Charcoal of any sort can open up the structure of dense clay soils, and allow water to permeate more thoroughly. And in sandy soils, the addition of the charcoal can help hold moisture in the soil longer, rather than letting it just drain through. And even a nice, sandy loam will benefit from the addition of charcoal.

The secret about charcoal in the soil is in how it is made. When you make charcoal, rice hull, wood chips, any kind, you are simply driving off most of the non carbon bits. This leaves a structure that is honeycombed with tiny pores. The cumulative surface area of this is immense! And they provide a home for billions of beneficial bacteria and other micro-organisms. These in turn release minerals from the soil for plants to use, fix nitrogen in the soil, and add to the biomass of the soil. Truly a win-win situation. As you probably remember from your Junior High School science lessons, the more organisms in an environment, the more stable it becomes. That is why a garden with charcoal added will show you fewer major pest problems, better soil texture, and more nutritious crops than a traditional chemical fertilized garden, and much better than a garden sprayed with pesticides.

Making the Rice Hull Charcoal

***This will produce a LOT of smoke***
It is not so hard, but you really should have a source of rice hulls nearby. if there is a rice- producing area nearby, getting your hands on rice hulls should be no problem. If there are none, you might try asking local nurseries if they can sell you some (many use rice hulls as a major component of their potting soils).
So, to make the charcoal, you will need a large tin can. The 10L cans of oil that are used in fryers would be great, try asking around your local greasy spoon cafe for their empties. You also need a short chimney, maybe two feet or so. Easy to find at a home center. And of course rice hulls . As much as possible. 10-15 hefty bags is not too many. Basically the volume will shrink by about 2/3. So 15 sacks of hulls makes about 5 sacks of charcoal.

Now be warned- this process involves fire and heat. Get permits if needed, and take precautions! I am not responsible for you!

Punch some holes in the sides of the tin can with a nail and hammer, etc... One every inch or two. It's not rocket science.
With a tin-snips, cut an X the diameter of your chimney pipe in the bottom of the can, and cut the top of the can right off. (we will use it upside-down)
Bend the four flaps up to allow the chimney to sit on the can. Now it should look like a factory with a smokestack.
Find a nice flat place that you can scorch. It should be away from trees and houses of course.

I have been experimenting with a 55 gal oil drum, cut in half- put the can and chimney in the drum
, and proceed as below. Keeps the rice hulls nicely contained, less mess.

Crumple up a few sheets of newspaper, maybe roll up a piece of cardboard and tuck it under the can. Then set up the chimney.
Pour rice hulls around the can. More is better. They should cover the can completely in a rough mountain shape.
Light a twist of newspaper and drop it down the chimney. It should light the newspaper and cardboard and begin the process. Keep an eye on the burning. There will be smoke. As you watch it, you may notice that the hulls are blackening on one side or the other. Try to cover them with uncharred hulls from the base or other side. Eventually, this will become impractical. When the rice hulls are mostly blackened, (80-90%) take out the chimney and can, rake the pile fairly flat, and turn the hose on them to extinguish the smoldering. They will dry quickly. You will probably have a few uncharred hulls. Don't worry. If you try to let it burn till they are all gone, you will have a lot less charcoal.

The mechanics of it are simple- by starting the fire under the can in the beginning, an updraft is created, drawing air through the hulls to the can, then up the chimney. Meanwhile, the hulls in contact with the can begin to burn. As this burn zone continues outwards, the charred hulls near the can can no longer burn, since the oxygen was consumed by the burn zone already. When all the hulls have been charred, then they begin to burn down to ash. You don't want that. That is why you should try and keep the blackened spots on the outside to a minimum until near the end.

Now using it in your garden- simply sprinkle it along the row if you are a row gardener, or add a garden trowel full to the square if you are a square foot gardener. Nothing could be easier! If you have a lot of it, you can try broadcasting it over the garden, but most experiments suggest that adding it along the row is the most effective.

Why does it help your garden? Well, for one, the rice hull charcoal is weakly alkaline, so if you add it to acidic soils, it should help to balance the PH towards the neutral range, where most plants grow better. The carbon will trap water and provide a home for micro-organisms- most of them beneficial. The black color will darken your soil and help it to warm up quicker in the springtime. The list goes on and on.
 (Charred hulls ready for the garden)

1 comment:

  1. When you make charcoal, rice hull, wood chips, any kind, you are simply driving off most of the non carbon bits. carbon powder uses