No, and the two black piles sit further apart than they look. Reaching for charcoal instead of biochar puts a material with no known specification into your soil. A product sold as biochar should tell you its feedstock and the heat it was run at. The research gathered here establishes neither one for a bag of grill fuel, so you would be guessing at what you just dug into the bed.
A bag of char went into the wheelbarrow of compost one spring, sold for garden use, and I noticed the problem at the first shovel. Coarse, gray, and ash on my gloves. Feedstock, burn temperature and particle size are what separate one char from another, and the bag either gives you those or it does not. By the third trip out to the beds I checked the label again and set that bag aside.
Specification is the whole argument here. Material sold as biochar tells you what plant matter it came from and how hot it was run, and that range sits at 660 to 1,290°F (350 to 700°C) with very little oxygen in the chamber. Utah State University Extension describes the result as a charcoal-like product that contains no petroleum. Better bags print one more number, a hydrogen to organic carbon ratio, and below 0.7 is the mark that says the carbon should hold in your ground.
None of those numbers come with grill fuel, and that is the honest shape of biochar vs charcoal. No source in this research evaluates barbecue charcoal as a soil amendment. So the answer is unknown, not proven harmful, and I would rather hand you that than dress a guess up as a finding. Heat is the part you cannot read off a cooled lump, and heat is part of what decides how a char behaves.
Size is the one variable your eye can settle. A chunky char and a dusty one came from the same idea and will not act the same in a bed. Not all biochars perform alike, and it tracks back to the same three things every time. That is three unknowns riding on one bag of briquettes, and briquettes were built to cook dinner.
pH is where a swap can bite. Char pushes soil pH up, and high-ash material pushes it hardest, which turns into a real problem on ground that already reads neutral or basic. On acid soil that lift can be welcome and even the whole point of adding it. On soil testing 7.0 or above, you are moving a number that was fine where it sat.
Any high-ash char raises pH. Get a soil test before you add char, and skip it on ground that already reads neutral or basic.
Buy material sold and specified as biochar, then read the bag before it goes in the cart. Feedstock and burn temperature should both be printed there, along with the stability ratio if the producer bothered to test for it. Two of those missing means put it back. Ask the seller if the bag stays quiet, because anyone running a real kiln knows the temperature and will say so.
Putting grill charcoal in soil is not a proven mistake, and I am not going to call it one. It is an experiment with no control, run on the beds you care about, with no number to check the result against. A bag of specified biochar comes with those answers printed on the side, which is the entire reason to pay for one.
One more line if you keep animals. Biochar and charcoal are both illegal to feed to US animals raised for human consumption right now, though they are approved for bedding. Worth knowing before somebody tells you to stir char into the feed bucket.
Read the full article: Biochar: What It Does and When It Fails
