One of my goals for this year is to make a biogas to run my propane grill, and while doing research for that goal I ran into articles about biochar. Biochar is basically defined as charcoal used for agricultural purposes. We all have probably seen or used charcoal in our BBQ grills, but most of that isn't good for the garden. In fact most of the commercial charcoal we buy at the store is made with chemicals we don't want in our garden bed. Biochar on the other hand is simple to make and is a great amendment to the garden.
Biochar isn't some new soil amendment either, to really find its start we have to go back in time to the ancient amazons. No one is really sure as to how or why the ancients started to make and add the biochar to their farmlands, but even today those farmlands are rich in fertility. What is known is that the biochar helps to retain nutrients and water in the soil, helping to prevent nutrient loss to leaching. This rich farmland is known today as Terra Preta.
"Terra preta literally "black soil" in Portuguese is a type of very dark, fertile anthropogenic soil found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil. It is very stable and remains in the soil for thousands of years."
How to make and Use Biochar
Biochar is created using pyrolysis, or heating biomass in a low oxygen environment. One of simplest forms of doing this is to dig a shallow pit and add some biomass. Biomass can be a mixture of weeds you don't want to compost, leaves, grass clippings, wood trimmings, and if you want, add in a few larger logs. Start a nice slow burning fire. Once your fire has calmed, cover it with a thin layer of dirt and let it smolder until the brush is charred and then put it out.
There are other options to digging pits, another option is to fill a metal container with the items you want to turn into biochar. You want to make sure that your container has a lid, and has a small hole to allow the gas pressure that is created to vent. You place this container in a fire and allow it to char.
To use biochar, we want to charge it up first. There are a few ideas on doing this. Option one is to mix the biochar with wet compost, allowing it to soak up some of the excess water and nutrients in the compost. Another option is to soak the biochar in a home brew of compost tea. If we don't charge the biochar, it can have a negative effect of first acting as a sponge, extracting water and nutrients in the soil.
Whats its effect
Biochar will help prevent leeching and runoff of water and fertilizer. If we can get our commercial growers to start adding biochar to their fields, we could diminish agricultural pollution as there is less need to add excessive amounts of fertilizer. It helps retain moisture, so plants are better able to survive the stress of drought conditions. It is also an important mega complex for soil microbes essential for plants survival. One can even see greater results by using biochar with commercial fertilizers, than if they just relied on the fertilizer. Below is a video showing some results.
So now I'm on the quest to make my own biochar. I've got plenty of tree trimmings laying around the back of the property. For those who don't have tree trimmings, remember that you can use things like waste lumber, even pallet boards, and even old weeds in the yard.
A friend from Home Farm Ideas wrote this. Post all your questions below:)