The one problem that I have had with Biochar, was how to adapt its production to the needs of industrial farming. I think that we can now make some progress.
First off, biochar is elemental carbon reduced by the application of heat to plant material usually drawn from crop wastes. The waste should not include woody material because it retains structural integrity and preserves difficult to reduce gross structure. We have determined that the likeliest feed stock is corn stover for several good reasons:
1 It produces at least ten tons per acre of material and often much more.
2 Unless converted to silage when green it is unsuitable for feed or for plowing back into the soil and is normally burned.
3 Once ripened, the water is drawn back down the stalks making the stover fairly dry.
4 It can be chopped or bailed for handling easily enough and its coarse nature encourages further drying under cover.
5 I have reason to believe it was the primary crop used by the Amazonian Indians to produce terra preta over a two thousand year span.
In short, we do not need to promote a new crop in order to produce biochar.
A lot has already been discussed about collecting plant waste for some form of power plant type facility. Let us cover the handling problem first.
I think it makes a lot of sense for a facility to accept chopped corn waste in exchange for a one for ten biochar load. A farmer would at his expense truck in typically chopped corn stover to the processing facility and receive back a chit for a load of biochar on a one in ten basis. A water content measure would be conducted and a penalty applied. Some time later (perhaps weeks) the farmer would return to pick up a load of biochar in the form of powdered elemental carbon. This process integrates smoothly into a farming operation without incurring significant costs but clearly defraying haulage and direct purchase costs for the processor.
The farmer has disposed of his waste for the cost of trucking it to the plant and he receives in return the produced biochar which he stores in fertilizer tanks. Before using the biochar, he can blend in fertilizer and apply the combined blend as he would fertilizer. It should be far gentler on the machinery also.
We know that a field of corn should produce at least a ton of biochar per acre, so this is a significant contribution even in its first year of operation. Obviously over many years, the carbon content of the soils will become dominant and worked deep into the soils.
Even at this initial level of amendment the crops will respond because fertilizer is been retained. Over several years the fertilizer needs will continue to decline freeing the farm from the need to supply heavy fertilization at all. Recall that in the tropical rainforest, such terra preta soils have been observed cropped continuously over sixty years without any amendment beyond the return of waste to the soil.
Thus we have shed the collection costs for our processing plant and have stored huge amounts of plant waste under cover so that it will continue to air dry. The next step is the plant itself.