Backyard Biochar
Want a way to help improve soil structure, enhance your soil’s water and nutrient-holding capacity and sequester carbon? Biochar is one tool that can help you do just that! It's a powerful soil amendment that helps enrich soils, enabling them to become more drought resistance, have better drainage, while also providing tiny microscopic "homes" for a thriving microbial world underground to support healthier, more disease-resistant plants aboveground. One famous example of biochar is its long use in the Amazon rainforest. It was used by indigenous communities to build up relatively poor jungle soils into "black gold" or "terra preta", enabling much more abundant harvests that could support millions of inhabitants. Terra preta soils are still prized for their fertility today and are known for their resilience and ability to build fertility over time (go soil microbes!). Using biochar to grow soil while also maintaining abundant yields is certainly a tool we could implement today in our own backyards!
Okay, okay, very exciting, you say, but what exactly is biochar? Biochar is different than wood ash or charcoal which loses most of its carbon to the atmosphere in burning. Biochar, on the other hand, is produced by burning carbon-rich materials like wood at very high heat in the presence of very little oxygen, effectively capturing the carbon in a very stable form with a complex microstructure. It makes an awesome little 5-star hotel complex for your beneficial microbes.
In recent years, the resources both around how to make your own biochar and where to source it locally have increased dramatically. Many garden centers now carry bags of it or you might be able to find a neighbor, local recycling center or local farmer who can source it or make it in bulk! Biochar can be made from any carbon-rich waste product: nut shells, woody invasive weeds like invasive bittersweet or multi-flora rose, tree trimmings, wood chips, corn cobs, you name it!
Biochar is an exceptional soil builder, BUT biochar can cause problems if used improperly. "Raw" or freshly produced biochar has a tendency to absorb water and nutrients like a sponge! So if you dump a large amount of it on a young plant or add tons of it to your soil, you will likely see problems as the biochar sucks up water and nutrients. The trick is to prepare or "supercharge" your biochar before you use it.
Here are 5 ways I prepare or SUPERCHARGE raw biochar:
1) Hydrate: Add moisture to your biochar. Freshly produced biochar has just had all the moisture, oils, EVERYTHING burned off. The easiest way to rehydrate fresh biochar is to water your pile with a hose or watering can. It can soak up a surprising amount of water. Get it wet and saturated but avoid making it into soup. You want a balance of air and water to get the best environment for those beneficial soil microbes...
2) Crush: Depending on where you get your biochar, you might have some pretty large chunks of log, branches or corn cobs turned into blackened stable hunks of carbon. Pound, crush and break up these larger chunks so that you have more surface area and a variety of sizes. Doing this step after it is moistened is helpful in reducing dust.
3) Mineralize. Add minerals to your biochar. Biochar has the AMAZING ability to hold onto both positive and negatively charged nutrients in the soil that might otherwise wash away. Adding biochar to the soil is like increasing the size of your soil's bank account or the amount of nutrients it can hold at a time. Mix biochar with nutrient dense mineral blends before adding it to you soil to take advantage of this cool trait. Rock dusts, high quality compost, mineral-rich clays and sea minerals are excellent options to add trace nutrients into the garden.
4) Add Beneficial Biology: There are many ways to add beneficial biology to your biochar. Sprinkle in inoculants or purchased blends of beneficial soil biology like a broad spectrum seed-starting inoculant or beneficial mycorrhizal fungi powder! It could be by mixing your biochar with a high quality compost, compost tea, or worm castings (worm bin compost!). There are also ways of culturing your local beneficial microbes if you want to try a hand at making your own inoculants with your own local beneficial biology like with Korean Natural Farming techniques, fermentation, or culturing your own effective microorganisms (EM) cultures. Liquid cultures and fertilizers like compost tea will hydrate, add biology and minerals all at the same time! Whoa.
5) Let It Sit. As a general rule, when I am mixing biochar with compost or worm castings or minerals or cultures or compost tea, I like to let it sit for at least 10 days before I add it to the garden. Can't wait that long? Experiment! See what works for you and your site. I have definitely known people who have beautifully rich soil and even use raw biochar with no problems. If you're new to biochar, go slow, start small and see what works best for you. If you try out a new idea, I would LOVE to hear about it!
"Worm castings" or worm poop from a worm composter bin is an excellent additive to biochar, full of beneficial biology and plant-accessible nutrients.
The only limit to using biochar in the garden is our creativity. Here are some creative ideas to get you started for using biochar in the garden:
Add raw biochar to your compost bin and let it "supercharge" as your compost is being made
Add it to animal bedding (goats, chickens, rabbits, ducks, guinea pigs, etc...) and then compost it. Biochar absorbs smells and adds structure to the composted manure before it gets added ultimately to the garden.
Dig inoculated biochar into strips or rows directly in the garden bed or along the borders each year at the beginning or end of the year. Alternate the direction of the rows to add a little more each year.
Sprinkle biochar lightly onto the soil surface of a lawn or around perennial plants.
Dig out soil cores around struggling trees and mix the existing soil with super-charged inoculated biochar before refilling the holes.
Using biochar is one way to build "an underground forest" with healthy roots, thriving microbial communities and resilient, drought-resistant soils!
Resources:
"The Secret of El Dorado: Terra Preta" - free on YouTube, a fascinating documentary on the fertile soils in the Amazon rainforest and the ancient practices that created them. (1 hour, but so worth it!) https://www.youtube.com/watch?v=0Os-ujelkgw&t=5s.