I can't answer your question directly; I have not used it in a mass area broadcast. But I'm very interested in the responses you will get.
If it's raw, unwashed char, you may get a temporary potassium boost, a temporary pH trend toward basic, and some other nutrients being locked into the char as it is colonized and turns into biochar. (Others here can speak with more authority.)
My question is, what do you have in mind? I think it depends on your objective. If you want an immediate 20-20-20 bloom of growth, you may be disappointed. If you want to build long-term fertility, tilth, soil complexity, then char is one factor that supports that goal.
In spring 2017 I applied about 20+ yards of compost that was 10-20% "activated" biochar to an intensively cultivated 4000sq ft set of beds. The plants yellowed and no matter how much nitrogen we threw at them. Eventually they would even start to get nutrient burn before greening. Beds with more native clayish soil and less added biochar compost greened up much better.
Then the whole region burnt in a wildfire. So I can't look up my receipt and give you more accurate numbers.
Then we cover cropped it for two years with pea family plants, rye and clover.
Now the biochar'ed beds are growing a ton of food, no noticeable nutrient deficiencies. No small pest or diseases. Rabbits are our only issue, but who needs lettuce anyhow?
I bought the biochar compost from the largest biochar company in northern California. I found them to be in denial when I called them during my nitrogen vacuum stage of the biochar. Their owner claimed their outsourced composting activation was fantastic and they hadn't received any other complaints. I think they were on fantasy island, but I'm no expert.
I do intend to make biochar onsite from some the thousands of dead trees, and activate is myself with thinned green brush compost, worm castings, flour, rock dust etc. I'll start making the biochar when burn season starts next month and will update. I also intend to compare this to biochar I purchase and activate myself. I wont be paying for other people to "activate" it again.
Efren Turner wrote:I do intend to make biochar onsite from some the thousands of dead trees, and activate is myself with thinned green brush compost, worm castings, flour, rock dust etc. I'll start making the biochar when burn season starts next month and will update. I also intend to compare this to biochar I purchase and activate myself. I wont be paying for other people to "activate" it again.
Efren, thank you for sharing that experience. That is classic for what you can experience with raw biochar. I'm a big fan of actually carrying out the composting process with the biochar added to the raw green and brown ingredients dispersed throughout the pile. That way as the compost pile ingredients break down the biochar can absorb the nutrients that would otherwise leach out or leave as vapors. Just adding finished compost to raw biochar has not been effective in my experience and the test bed I did that with acted like I added raw biochar to it. I have not tried the approach you've mentioned where you add a carbohydrate source like flour as one of the ingredients to kick up more biological activity. That may make all the difference. Would love to hear how that works out for you. I have heard that it works well, I just haven't wanted to use a finished good like flour on my biochar when I have a constant stream of material that needs to be composted anyway.
Not yet, but hoping to start soon. My plan is to add it to the legume part of my crop rotation. Since they fix their own nitrogen, they aren't as affected by the "nitrogen vacuum" stage. If I can keep it up for 4-5 years, I'll have covered my whole field.
We'll see if I can keep it up. It's one of those things that keeps getting bumped on the priority list.
I've got a large amount of feedstock from a grove of white pines that are closely spaced and are self thinning. I am considering turning a large quantity of it into biochar to be broadcast around my fruit and nut trees. I would probably inoculate it with manure.