Making Your Own Biochar

Imagine if you could save the earth by starting a fire in your garden.

Sounds crazy? Maybe, but maybe not.

Biochar can sequester carbon into the soil, improve soil conditions by retaining water and nutrients, and provide a home for microorganisms. And it’s not a new thing, the earliest known use of biochar was in the Amazon jungle, two to three thousand years ago.

But what exactly is biochar? How do you make it? And how do you use it?

Biochar looks a lot like charcoal, but it’s not. What makes biochar different from charcoal is that it's burned in a particular way. More on that later. Biochar is made up of dead plant material but can include manure, and is mostly stuff that’s hard to compost. Examples of what you can make biochar from are twigs, sticks, untreated wood chips and scraps, small logs, leaves, and tough stalks. Items you wouldn’t put in a compost pile because they would take too long to break down or breaking them down into easily compostable pieces isn’t really feasible. This is also called biomass. Biochar is a soil amendment that can help with global warming by sequestering carbon into the soil. Also the charred plant material has many nooks and crannies for catching nutrients, microorganisms, and water and that can help turn poor soils to productive ones. It is an excellent soil amendment.

Carefully. Since it involves burning plant material, please check with your municipality and your fire department to see if it’s allowed and if there are any requirements or permits needed. If your area is in a drought, be especially careful. All fire safety cautions should be observed, including but not limited to having a way to put the fire out in case things get out of hand, keeping it away from any structures, and never leaving the fire unattended ever. Check with your local fire department. They would much rather you ask them for help now than call for help later.

Biochar is different from charcoal because it burns at a lower temp with less oxygen than charcoal. One of the easiest ways to make biochar is to dig a trench deep enough to fit the biomass. A foot or two deep and as wide as you want and have material to fill it. If you have heavy clay soils, you may need one of these.

Fill your trench with leaves, sticks and small branches. Dry material works best. You want a hot fire that burns clean. You keep adding material, carefully. You don’t want to smother the fire but you also don’t don’t want everything to burn too fast. There’s a bit of a learning curve, and with experience, you will figure it out. You want to keep the fire going, without any smoke. Some smoke in the beginning is okay. Your material may have some hidden moisture that needs burning off. Once everything is burned and ash is starting to form on what remains, now is the time to slow things down. Cover the trench with the soil. You need to cut off oxygen to the fire, which lowers the temperature and slows the burn rate to produce biochar. You need to make sure that you completely cover the trench and that there’s no smoke escaping from anywhere. And now you wait. On average it may take five hours to complete the transformation into biochar. You can do a test by digging a hole. If you see smoke, cover it back up and wait some more.

It can be as easy as planting next year's crops right on top of your burn trench. Or you can turn over the soil and newly made biochar to mix it up. Or you can dig it up and use it to amend your beds. You can simply use it as a soil amender as you would compost. Since biochar starts out sterile, there are no microorganisms in it. However, it is a very nice place for them to live. You can give it a head start by mixing it with organic fertilizer and/or compost. Eventually all those nooks and crannies will fill with microorganisms, nutrients and happy plant roots.

Biochar, while not that difficult to make, does require attention and care. It can help build soil structure and improve poor soils, and it can help reduce global warming by sequestering carbon into the soil and reducing and reusing plant waste. If you can make it safely, it can be a key part of keeping you garden healthy.

Imagine if you could save the earth by starting a fire in your garden.

Sounds crazy? Maybe, but maybe not.

Biochar can sequester carbon into the soil, improve soil conditions by retaining water and nutrients, and provide a home for microorganisms. And it’s not a new thing, the earliest known use of biochar was in the Amazon jungle, two to three thousand years ago.

But what exactly is biochar? How do you make it? And how do you use it?

Biochar looks a lot like charcoal, but it’s not. What makes biochar different from charcoal is that it's burned in a particular way. More on that later. Biochar is made up of dead plant material but can include manure, and is mostly stuff that’s hard to compost. Examples of what you can make biochar from are twigs, sticks, untreated wood chips and scraps, small logs, leaves, and tough stalks. Items you wouldn’t put in a compost pile because they would take too long to break down or breaking them down into easily compostable pieces isn’t really feasible. This is also called biomass. Biochar is a soil amendment that can help with global warming by sequestering carbon into the soil. Also the charred plant material has many nooks and crannies for catching nutrients, microorganisms, and water and that can help turn poor soils to productive ones. It is an excellent soil amendment.

Carefully. Since it involves burning plant material, please check with your municipality and your fire department to see if it’s allowed and if there are any requirements or permits needed. If your area is in a drought, be especially careful. All fire safety cautions should be observed, including but not limited to having a way to put the fire out in case things get out of hand, keeping it away from any structures, and never leaving the fire unattended ever. Check with your local fire department. They would much rather you ask them for help now than call for help later.

Biochar is different from charcoal because it burns at a lower temp with less oxygen than charcoal. One of the easiest ways to make biochar is to dig a trench deep enough to fit the biomass. A foot or two deep and as wide as you want and have material to fill it. If you have heavy clay soils, you may need one of these. Less compacted soils, you should be able to use one of these.

Fill your trench with leaves, sticks and small branches. Dry material works best. You want a hot fire that burns clean. You keep adding material, carefully. You don’t want to smother the fire but you also don’t don’t want everything to burn too fast. There’s a bit of a learning curve, and with experience, you will figure it out. You want to keep the fire going, without any smoke. Some smoke in the beginning is okay. Your material may have some hidden moisture that needs burning off. Once everything is burned and ash is starting to form on what remains, now is the time to slow things down. Cover the trench with the soil. You need to cut off oxygen to the fire, which lowers the temperature and slows the burn rate to produce biochar. You need to make sure that you completely cover the trench and that there’s no smoke escaping from anywhere. And now you wait. On average it may take five hours to complete the transformation into biochar. You can do a test by digging a hole. If you see smoke, cover it back up and wait some more.

It can be as easy as planting next year's crops right on top of your burn trench. Or you can turn over the soil and newly made biochar to mix it up. Or you can dig it up and use it to amend your beds. You can simply use it as a soil amender as you would compost. Since biochar starts out sterile, there are no microorganisms in it. However, it is a very nice place for them to live. You can give it a head start by mixing it with organic fertilizer and/or compost. Eventually all those nooks and crannies will fill with microorganisms, nutrients and happy plant roots.

Biochar, while not that difficult to make, does require attention and care. It can help build soil structure and improve poor soils, and it can help reduce global warming by sequestering carbon into the soil and reducing and reusing plant waste. If you can make it safely, it can be a key part of keeping you garden healthy.