Nando;

Your comments make a lot of sense except for differences with what I have seen. Not at all sure how to explain the differences we see between you and me. 

I think your comments on the microbes living on char are on target. Your comments on 'nutrient penetration' are also on target. But, grinding the char to increase the surface area does undoubtedly increase the surface area but as far as I can does does not have a response from plants growing in the immediate area. So far, and I am waiting to see it happen. Functionalizing char by grinding "to make it have a quicker response time for crops' has not happened anywhere in the literature or in any crop soils I have seen. There are three accomplished organic gardeners in my area, all of whom have soils at least six years old. My biochar soil is now 13 years old. We have all seen the same response - five years to maximum crop response. Researchers have been trying functionalize biochar for some time and they have uncovered some very interesting chemical, biological and functional things happening. But, they have not created a quicker response time for the crops. It still takes five years for full crop improvement. Saw it happen over a period of five years in my experimental garden. I have applied 10% biochar over about a five year gradually year by year. I did not keep track of the amount of biochar applied per year. I was lucky in that Claire Phillips at Oregon state University could do a test of my soils on year six and she calculated 10% by volume. The question is, if 10% were applied all at once, when my crop response be the same. From all that I have seen my intuitive answer is yes. Soil fertility is a function of microbe growth and change. From what I have seen, our interpretations of physical sizes of biochar particle articles is only an interpretation that seems to fit. We still do not understand the microbial goings-on around the biochar particles. When I read that electron transport on nutrient elements can proceed for distances far greater than anyone expected, I began to suspect there is a basic chemistry we are only now uncovering and beyond that, it seems to be a function of the microbes. I would love to see an experiment detailing changes in the microbial community before and after the application of biochar as a function of the minimum five year time period.

What percent of biochar exist in your soil? My soils are described as a Clay loam and I wish they were. They are not. They are a Clay sand subsoil which I have transformed using organic matter and green kitchen waste and chicken manure. 

You and I might disagree on interpretation. But that's okay because the cutting edge of science is often based on nothing more than intuition and possible interpretations and then discussing it. Thanks.

Norm