Biochar enriched soils, also known as terra preta, have been proven to increase microbial life and have also been proven to grow plants bigger and faster than soils without this amendment. I have seen similar, anecdotal results in my medical cannabis garden. The beds utilizing biochar not only grow bigger plants, but the soil seems last longer as well. It’s unclear exactly why the soil lasts longer, but I’m left to assume that the biochar is able to buffer toxicities that may build up in the soil otherwise.
Biochar is a form of charcoal made through a specific pyrolisis process that results in pure carbon. You can certainly make biochar at home, but you will want to avoid using large pieces and powder in your soil mixes. Large pieces take up too much space and carbon powder can cause compaction in the soil. I like to use small (1/2 pea size) pieces only at a 10% rate. This means that for every 10 gallons of soil I’ll mix in one gallon of biochar.
These tiny chucks of charcoal function much like an apartment building for microbes and bacteria. Once exposed to nutrients, it will absorb them, and now you have an apartment building with a large buffet of food. The pores of the biochar are just the right size for microbes and fungi while being too small for most of their predators. Is it fair to say that it is a gated community for microbes?
Beyond retaining nutrients and providing living spaces for beneficial microbes, biochar will also retain water so that less water is needed through out the growing cycle. I’ve found that my beds with biochar need about 20%-30% less water than the beds without biochar. Biochar also boosts the cation exchance capacity (CEC) and helps buffer the PHa measure of the acidity or alkalinity of a solution More of soil. Yes, I’ll be amending all my beds with biochar in their next cycles!
Finally, I plan to add about 5% biochar to my worm bins so that as the worms decompose nutrients through their digestion process the biochar will become charged with nutrients and microbes. I soak my biochar in a nutrient mix comprised of worm casting tea and fish hydrolysate and my plants love it. Once I’ve established my worm colonies I’ll be able to skip that step.
Have you used biochar? Does it provide you with great results? Let us know.
Happy Harvests!
— The Lit Farmer —