A little while ago we went to a biochar workshop by Pete of Kernow Black. He did a small scale demonstration of the creation of biochar, as well as discussing the topic.
So what is biochar, and why can putting in the ground help your garden and the environment? In order to answer this we need to know a little bit about the carbon cycle, here is an explanation taken from UCAR:
There are a few types of atoms that can be a part of a plant one day, an animal the next day, and then travel downstream as a part of a river’s water the following day. These atoms can be a part of both living things like plants and animals, as well as non-living things like water, air, and even rocks. The same atoms are recycled over and over in different parts of the Earth. The most common of these are the carbon and nitrogen cycles. Tiny atoms of carbon are able to move around the planet through biogeochemical cycles.
- Carbon moves from the atmosphere to plants. In the atmosphere, carbon is attached to oxygen in a gas called carbon dioxide (CO2). Through the process of photosynthesis, carbon dioxide is pulled from the air to produce food made from carbon for plant growth.
- Carbon moves from plants to animals. Through food chains, the carbon that is in plants moves to the animals that eat them. Animals that eat other animals get the carbon from their food too.
- Carbon moves from plants and animals to soils. When plants and animals die, their bodies, wood and leaves decays bringing the carbon into the ground. Some is buried and will become fossil fuels in millions and millions of years.
- Carbon moves from living things to the atmosphere. Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants need to get rid of carbon dioxide gas through a process called respiration.
- Carbon moves from the atmosphere to the oceans. The oceans, and other bodies of water, absorb some carbon from the atmosphere. The carbon is dissolved into the water.
Recently, people have been causing these biogeochemical cycles to change. When we cut down forests, make more factories, and drive more cars that burn fossil fuels, the way that carbon and nitrogen move around the Earth changes. These changes add more greenhouse gases in our atmosphere and this causes climate change.
- Carbon moves from fossil fuels to the atmosphere when fuels are burned. When humans burn fossil fuels to power factories, power plants, cars and trucks, most of the carbon quickly enters the atmosphere as carbon dioxide gas. Each year, five and a half billion tons of carbon is released by burning fossil fuels. Of this massive amount, 3.3 billion tons stays in the atmosphere. Most of the remainder becomes dissolved in seawater.
Carbon dioxide is a greenhouse gas and traps heat in the atmosphere. Without it and other greenhouse gasses, Earth would be a frozen world. But since the start of the Industrial Revolution about 150 years ago humans have burned so much fuel and released so much carbon dioxide into the air that global climate has risen over one degree Fahrenheit. The atmosphere has not held this much carbon for at least 420,000 years according to data from ice cores. The recent increase in amounts of greenhouse gasses such as carbon dioxide is having a significant impact on the warming of our planet.
Hopefully this explanation makes it clear how the human interference on the carbon cycle has effected it’s natural balance. Biochar is one way of returning carbon to the ground. But it can also have benefits for your garden.
One of the things we learned at Pete’s workshop is the importance of charging the biochar with microorganisms before burying it. As Pete explained it: because of the structure of biochar, it can act as a sort of sponge. If put in an area of depleted ground just as it is, it can actually suck a lot of the available nutrients out of the ground making your problem of difficult ground to grown on even worse for the short term. However, if you ‘charge’ your biochar with bacteria before introducing it to the ground, it will serve as a sort of starting point for introducing new nutrients that you need.
Biocharging (inoculating) your biochar is easy, there are two main ways, compost charging and rapid charging:
For compost charging simply mix the biochar in with your compost heap where it will absorb all the beneficial micrones produced during the decomposition of your compost. If you have animals, you can spread your biochar an inch thick or less into your farm animal bedding. Then, when the bedding is spent, add it to the compost pile. The biochar is essentially ‘double-charged’ in this way. Also, in addition to stacking functions of your animal bedding, this can help reduce odors. Anecdotal evidence suggests it can also reduce illness among your animals!
For rapid charging soak your biochar in a microbe rich solution. Fill a drum with fresh water and biochar. If you are using treated water, let it sit for a couple days to remove any chlorine. Then add compost tea or worm castings and some soil from the area where you will use the finished biochar (this will help charge the biochar with the ideal microbiology for your specific area). To aid the process insert a long tube into the barrel and direct air into the tube. Aeration supercharges the inoculant giving the beneficial microbes a massive head start, and helping them adhere to the biochar. Continue this for 12-24 hours.
You can also use microorganisms from your food, for example: cook rice, take some leftover water and grains, let it sit for a week. Or, use left over kefir or kraut. Then soak the biochar in your liquid.
If you want to read further, take a look at The Big Biochar Experiment for more information on biochar research within the UK.