Don
It is an interesting subject, although this reply may be outside the remit of growing.
It is a sustainable form of farming, I think it is being adopted by farmers in practice as well.
I have not read up on it completely but it is being researched.
But to round the circle if municipal authorities are moving towards biodesters for dealing with organic waste materials, as are sewage works, to produce electricity.
The waste pellets are then passed on to power generation plants where the last bit of energy is extracted from the pellets produced by the bio-digesters.
Then would it not make sense if they burnt that with a low oxygen content producing bio-char which could then be used in farming.
As far as I can tell the bio-char acts like fertilizer and it lasts in the soil for a long time, locking up carbon essentially from the atmosphere.
Could be used as part of geo-engineering which is currently in the process of development.
To me that is what sustainability is about, mostly from a food growing angle but that all the raw materials we take out of the earth should be returned in one form or another or just simply recycled.
Burying waste from our over consumptive society is not the solution, we need to close the feedback loops which is what sustainability is about to me.
If bio-char does increase soil productivity without the use of chemical fertilisers derived from petro chemical industry, then does it not make sense to do that from a sustainable source?
If we have increased demand on land use, then does it not make sense to make the land we do use for growing food more productive to do it a way that is sustainable?
The problem that no one is talking about very much or least as far as governments go is exponential population growth. The elephant in the room, it is itself is not sustainable, it’s an oxymoron.
Something has to be done about population growth globally, it is none sustainable at some point when that growth meets its maximum, populations will collapse, it is inevitable.
In the natural world for example a plague of locusts can ravage a landscape, until they run out of food, then they die. It is more complicated than that but essentially we are forgetting that we are part of an organic living system, we think we are above it and that that can not or will not happen to use.
As far as I know there is a biochar producer in the UK, it is not cheap, not sure of what the application rate is but I for sure will be using it.
Whereas Rockdust does pretty much the same except that it re-mineralises the soil, not so much of a problem for small scale growing but essentially it ensures that the soil has all the minerals that it needs. There are some minerals which are lacking in most UK soils.
As small scale growers then to me we should not abandon either biochar or the use of Rockdust but use it as a general purpose application/addition to our soil.
It helps with keeping the soil healthy, locks up excess carbon from the atmosphere and traps it in the soil.
As for how I would use them, I would use them as a layer in my compost bin, along with lime, as my assumption is you do not need much of them. The application rates I have seen suggest that is for industrial farming practices.
Why would I do it?
To ensure that all the micro/macro flora and fauna in my growing space as well as the plants/vegetables are given all that they need to survive in a healthy environment.
Where a whole food chain exists from the smallest living organism to the larger predators/prey species. At the same time giving me the healthiest fruit and vegetables which will lack 57 varieties of herbicide and pesticide as in some recently tested supermarket apples. YUCK!!!!
On a health and population angle, all those additives can not be healthy for us in the long term and frankly I for one think it is a ticking bomb that we setting up for future generations.