I love growing food in my biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More garden, and as a true nerd, part of the fun for me is getting to do some science experiments with biochar. Here is an experiment I did this summer testing drought resistance in biochar-amended soil. I tested different application rates against a control.

I had twelve Cherokee Purple tomato seedlings that I could not find room for in the garden and I used those for the experiment, potting them up from four-inch pots to half-gallon pots with different soil mixes. I tested four treatments with three replicates of each:

1. Control – Fox Farms Ocean Forest Potting Soil

2. Biochar compost – a 50:50 mix of my biochar compost and Fox Farms soil

3. Biochar 25% – a 25:75 mix of charged biochar and Fox Farms soil

4. Biochar 50% – a 50:50 mix of charged biochar and Fox Farms soil

The charged biochar was made with five gallons of Rogue Biochar from Oregon Biochar Solutions soaked in 5 gallons of water, 1/2 cup of fish hydrolysate, 1/2 cup of EM-1, and 1/4 cup of wood vinegar, soaked for 24 hours and then drained and allowed to sit for 12 hours before adding to the soil. I let the plants grow for three weeks and then cut off all the water. Sitting in their pots in the hot July sun, they started to wilt. Here is what they looked like after five days:

To my eyes, the control is the only one that is clearly different and worse than the others. I also think that #2, the biochar compost did a little better than the biochar at 25% and 50%. I did not see much difference between the two biochar application rates.

Interesting! I was expecting to see more dramatic results but then I realized that the Fox Farms Potting Soil is a premium product with peat, perlite and other ingredients formulated for holding on to soil moisture and nutrients. If I had made the comparison to a cheap potting soil from the grocery store, or to plain dirt from the yard, I think the differences would have been much greater.

Even so, the biochar still helped and my conclusion is that every truly premium potting soil manufacturer should add biochar to the mix.

If you want to read my full post, Summer: How It’s Going in the Biochar Garden you can find that on my Substack, The Biochar Prepper.